fig 11

Interpreting an Unwrapped Interferogram: Creating a Deformation Map

Source: ASF Staff — Adapted from a RUS Copernicus Webinar (https://rus-training.eu/training/land-subsidence-mapping-with-sentinel-1)
Level:   Intermediate-Advanced

Continuing from the recipe How to Phase Unwrap an Interferogram, this final InSAR recipe will bring our unwrapped phase information out of abstraction into actual displacement units (meters). This recipe will go over the steps of converting the phase values to line-of-sight or vertical displacements as well as discarding data of low correlation that is likely unreliable.

Interpretation

Coherence
Coherence values must also be recognized in order to assess the validity of our displacement map. In general, coherence is the relative uniformity of phase difference between two interfering waves. In the context of SAR interferometry, this assessment is estimated from the random noise andamplitude differences that exist within a resolution cell, or pixel as viewed in the S1TBX. Areas of decorrelation (loss of coherence) should be ignored when interpreting accurate displacement values.

Coherence loss is cumulative from multiple sources:

  • Temporal changes such as the growth of vegetation or snow fall
  • A low signal to noise ratio
  • Weak signal return
  • Altitude changes in the range or azimuth directions (coherence is most severe when this difference is within a resolution cell)

This recipe will go over the steps necessary to remove incoherent data from the displacement map.

Geometry
The displacement values themselves can be ambiguous also be ambiguous. First, they are a measure of the line of sight component of displacement only. This can be converted to a vertical displacement using trigonometry but this assumes that all of the motion was actually vertical. Earthquakes for example can produce displacements in any direction. Second, it can be difficult to tell if a positive value refers to uplift or subsidence. Because the previous recipes in this series used the earlier SLC as the master image, we are assuming the positive value refers to uplift. In the phase values, the opposite is true since this is a measure of how much the satellite has moved away from the ground, not the other way around.
The phase to displacement conversion includes a negative sign which corrects for this.

Background

This recipe covers the final steps in deriving displacement data from a Sentinel-1 SLC pair (and interferogram), and builds on two other ASF Data Recipes. A wrapped inteferorgram is generated using the ASF Create an Interferogram data recipe, then the ASF Phase Unwrapping recipe walks you through unwrapping the interferogram. This recipe picks up where the Phase Unwrapping recipe left off.

In order to create a deformation map from an unwrapped interferogram, phase values must first be converted to displacement (in meters). This displacement value is derived from the differential phase values in the line of sight of Sentinel-1. Hence, the displacement value will also be relative to the sensor at the look angle, or angle of incidence, and not an absolute vertical displacement.

Coherence values must also be determined in order to assess the validity of our displacement map. In general, coherence measures how well the twoimages that formed the interferogram are correlated. In the context of SAR remote sensing, this assessment is estimated from the random noise andamplitude differences that exist within a resolution cello, or pixel as viewedin the S1TBX. Areas of decorrelation (loss of coherence) should be ignored when interpreting accurate displacement values.

Coherence loss is cumulative from multiple sources:

  • Temporal changes such as the growth/movement/harvest of vegetation or snow accumulation/melting between the two SLC images
  • A low signal-to-noise ratio
  • Weak signal return
  • Altitude changes in the range or azimuth direction (coherence loss is most severe when this difference is within a resolution cell)

Consequently, coherence tends to be highest in urban areas due to lowtemporal decorrelation and high backscatter intensities. Low coherence is indicative of water bodies and areas with a high vegetation index. Processes such as erosion and deposition can also cause decorrelation depending on the degree of backscatter divergence.

This is exemplified in the area surrounding the cities Kumamoto and Fukuoka in Japan (Figure 1). In this image indicating coherence levels, the Chikugo River (top left) is easily visible as a result of its low coherence (dark) values in contrast to the surrounding bright urban areas. Compared with an optical view from Google Earth (Figure 2), highly vegetated and undeveloped areas correlate with lower coherence.

fig 1
Figure 1: Geocoded coherence band. Contains modified Copernicus Sentinel data (2016) processed by ESA.
fig 2
Figure 2: Kumamoto and Fukuoka cities viewed in Google Earth. Imagery © 2018 Landsat/Copernicus, Data SIO, NOAA, U.S. Navy, NGA, GEBCO. Map Data © 2018 Google, SK telecom, ZENRIN.

Prerequisites

System Requirements

  • Windows, Mac OS X, or Unix computing environment
  • 16 GB RAM
  • At least 50 GB of available disk space

Note: A Solid State Drive will perform significantly faster than a Hard Disk Drive and when processing large files, this will be very advantageous.
If you encounter an error in the middle of a processing step, it may be because your disk is full.

Materials List

  • The latest version of Sentinel-1 Toolbox (S1TBX).
    • The software that runs S1TBX is called SNAP. Open the application by double-clicking the desktop icon, or searching for SNAP software among your computer programs. The software can be downloaded from the ESA SNAP Download page.
    • Make sure that any available updates have been applied. A message will usually display in the bottom right corner when updates are available, but you can also check by selecting Check for Updates from the Help menu.
  • The unwrapped interferogram with phase and coherence bands (Figure 4) generated by following the ASF Phase Unwrapping data recipe.
    • If the product is not already open in S1TBX, open the .dim file of the unwrapped phase (not Geocoded/Terrain Corrected).
    • The following source granules are used to generate the interferogram that is subsequently unwrapped and used in this recipe. They are provided for reference only, but if you have not yet followed the previous two recipes, you will need to download them.

Pre-event sample SLC:
S1A_IW_SLC_1SSV_20160408T091355_20160408T091430_010728_01001F_83EB
Post-event sample SLC:
S1A_IW_SLC_1SSV_20160420T091355_20160420T091423_010903_010569_F9CE

Pre-Processing Review

Create a Differential Interferogram

Detailed information on completing this procedure is covered in the ASF Interferogram Generation data recipe. The diagram shown in Figure 3 and the list of the processing steps, which reference the menu options leading to the tool for each step, give an overview of the steps required to generate a wrapped interferogram.

Figure 3: Visualization of the interferogram generation workflow.

a) Coregistration
Radar > Coregistration > S1 TOPS Coregistration > S-1 TOPS Coregistration
b) Create Interferogram
Radar > Interferometric > Products > Interferogram Formation
c) Deburst
Radar > Sentinel-1 TOPS > S-1 Deburst
d) Topographic Phase Removal
Radar > Interferometric > Products > Topographic Phase Removal
e) Multilook
Radar > Multilooking
f) Goldstein Phase Filtering
Radar > Interferometric > Filtering > Goldstein Phase Filtering

Note: This process chain does not include a Geocoding step. This will be done near the end of this recipe, once the deformation map is generated.

If you geocoded the Unwrapped Interferogram in the previous recipe, make sure to use the product from the step prior to geocoding (not tagged with a _TC) for the next step.

Unwrap the Interferogram

Detailed information on completing this procedure is covered in the ASF Phase Unwrapping data recipe. A brief overview of the steps in that process is presented below.

a) Snaphu Export
Radar > Interferometric > Unwrapping > Snaphu Export
b) Snaphu Unwrapping in a Linux command line
c) Snaphu Import
Radar > Interferometric > Unwrapping > Snaphu Import

Note: This process chain again does not include a Geocoding step. This will be done near the end of this recipe, once the deformation map is generated.

If you Geocoded the Unwrapped Interferogram in the previous recipe, make sure to use the product from the step prior to geocoding (not tagged with a _TC) for this next step.

At this point, you should have an unwrapped interferogram (Figure 4) loaded into the Sentinel-1 Toolbox (S1TBX). This recipe will resume from here.

fig 4
Figure 4: Segment of a snaphu imported unwrapped interferogram (without Terrain Correction). Contains modified Copernicus Sentinel data (2016) processed by ESA.

Steps to Create a Deformation Map

Step 1: Convert Phase to Displacement

This step converts the unwrapped differential phase value (radians) to a displacement value (in meters) along the line of sight of the sensor.

This is computed using the following equation:

Where λ is Sentinel-1’s C-band SAR wavelength and is the unwrapped phase difference between the two SLC images.

1. Select the imported and unwrapped interferogram in the Product Explorer window in S1TBX. If the Product Explorer window is not open, select Tool Windows from the View menu and select Product Explorer to open it.

2. Navigate to Radar > Interferometric > Products > Phase to Displacement.

menu

Figure 5: Segment of the resultant displacement map. Contains modified Copernicus Sentinel data (2016) processed by ESA.

3. In the Phase to Displacement window, specify the output folder and the target product name.

    • The products will automatically be appended with the suffix “_dsp” if you choose the default name.
    • There will be no options available in the Processing Parameters tab. Click <Run> and allow the image to be processed. The new product, appearing in the Product Explorer window, will have a single band (Figure 5).

Estimating Vertical Displacement Using Band Maths

Vertical displacement can be estimated if it’s assumed that there is no horizontal motion parallel to the sensor’s line of sight. This can be computed via Band Maths instead of the Phase to Displacement operator.

These steps using Band Maths are included as extra information only; the rest of this recipe uses the line-of-sight displacement band generated with the Phase to Displacement operator in the previous step.

Absolute vertical displacement in a setting with no horizontal movement can be calculated with the following expression, where the number 0.056 is the approximate value of Sentinel-1’s wavelength in meters:

(0.056 * Unw_Phase_ifg_08Apr2016_20Apr2016) / (-4 * PI * cos(rad(incident_angle)))

1. In the Product Explorer, right click the unwrapped interferogram product and select Band Maths.

2. In the Band Maths window (Figure 8), set the Name to something appropriate, such as Vertical_Displacement.

a. Enter meters in the Unit field.
b. Uncheck Virtual.
c. In the Band maths expression field, paste the expression listed above.

3. Click <OK>. The new band will appear in the bands directory and when viewed, should look very similar to Figure 5.

Step 2: Create Stack

The Phase to Displacement operation outputs only one band. To verify the accuracy of our data, we still need the coherence band created when the interferogram was first generated. Creating a stack will merge the _dsp product with the imported unwrapped interferogram.

1. Navigate to Radar > Coregistration > Stack Tools > Create Stack.

menu2

 

2. In the ProductSet-Reader tab of the Create Stack window, select the unwrapped interferogram and the _dsp product created in Step 1.

3. In the Write tab, specify the target product name and the output folder. The products will automatically be appended with the suffix “_Stack” if you choose the default name.

4. Click <Run> and allow the stack to be formed. The new product will appear in the Product Explorer window and will include the bands from both products.

Step 3: Range-Doppler Terrain Correction

The Range-Doppler Terrain Correction operator applies a series of processes to the displacement map.

First, it uses a Digital Elevation Model (DEM) to mask out areas without any elevation, including the ocean. This is helpful because none of the phase or displacement data over the ocean is useful.

Second, it uses the DEM and a map projection system to orthorectify the image, projecting it onto the Earth’s surface in its proper orientation. This operator also geometrically corrects SAR data, but this is not as relevant to this procedure as we only care about the included displacement and coherence bands which no longer include terrain geometry.

1. Select your _Stack product in the Product Explorer

2. From the menu bar, navigate to Radar > Geometric > Terrain Correction > Range-Doppler Terrain Correction.

menu3

Figure 6: Range Doppler Terrain Correction window.

3. In the I/O Parameters tab in the Range-Doppler Terrain Correction window (Figure 6), specify the target product name and the output folder. The products will automatically be appended with the suffix “_TC” if you choose the default name.

4. In the Processing Parameters tab, set the Map Projection by clicking on the Map Projection option. In the window that appears, select UTM Zone / WGS 84 (Automatic) from the Projection options. This will apply the appropriate UTM zone for the image location (best for GIS).

NOTE: If you want to export KMZ files for use in Google Earth as your primary product, leave the Map Projection as WGS84(DD).

Also note that the SRTM, which is the default DEM, does not have coverage beyond 60 degrees north and south. If your granules are located above 60 degrees north, you will need to select a DEM that covers that area, such as ACE30.

5. Leave the rest of the parameters as default and click .

6. When processing is complete, close the Correction window and view the product (Figure 7) by double-clicking the band.

Figure 7: Geocoded displacement map. Contains modified Copernicus Sentinel data (2016) processed by ESA.

Step 4: Mask Out Areas of Low Coherence

1. In the Product Explorer, right-click the terrain corrected displacement map stack created in Step 3 and select Band Maths.

Figure 8: Band Maths Window.

2. In the Band Maths window (Figure 8), set the Name to something appropriate, such as Masked Displacement.

3. Copy and paste the following expression into the Band maths expression field:

if coh_IW1_VV_20Apr2016_08Apr2016 > .3 then displacement_slv1_20Apr2016_VV else NaN

4. Click <OK>. A new band will appear in the product’s Bands folder, and the image will appear in the view area (Figure 9).

Figure 9: Displacement map with areas of low coherence masked out. Contains modified Copernicus Sentinel data (2016) processed by ESA.

This Band Maths expression will create a new displacement band where areas of low coherence (unreliable data) are removed. If the coherence value is greater than 0.3 (on a scale from 0 to 1), the new band will use values from the displacement band. If the coherence value is 0.3 or less, the pixel will be set to a NoData value.

The threshold can be set to any value, and you may find that you require a different value depending on the situation. You can easily build your own expression by clicking the Edit Expression button.

Step 5: Update Color Scheme

1. Ensure that the masked displacement band is open and displayed in the view area.

2. Click on the Colour Manipulation tab in the lower left corner of S1TBX to view the Color Manipulation window (Figure 10). If the Colour Manipulation window is not open, select Tool Windows from the View menu and select Colour Manipulation to open it.

Figure 10: Colour Manipulation Tab.

3. Click the circle by Sliders in the top left corner of the window if necessary to open the Sliders Editor view (see Figure 10).

4. Click on the Rough Statistics! text in the top right of the graph pane and click <Yes> in order to calculate accurate displacement statistics for the color scheme.

5. Select the Basic view in the top left region of the tab. Select great_circle from the colour ramp options, and click the Range from Data button.

6. Return to the Sliders view. Right-click the triangle slider on the far left of the color scale and select Remove Slider.

There are two sliders almost on top of each other on the left side of the color ramp, and this will remove the extra one.

7. Select the Table view. There should be three entries with data values listed for each color: blue, white and red. If the first color is black, click on the colour patch and change it to blue. Double-click on the value next to white and change it to 0. Press Enter to apply the change. If there are more than three values, return to the Sliders view and remove the extra sliders.

The resulting displacement map (Figure 11) displays the change in the distance along the line-of-sight from the sensor to the earth’s surface.

If the image acquired on the earlier date was used as the master in this process, positive values (displayed in red on this color scale) will indicate areas that are closer to the sensor in the later acquisition than they were in the earlier acquisition. This could indicate either vertical uplift or horizontal displacement in the direction towards the sensor, but is most often a combination of both.

Figure 11: Displacement map colored with red indicating uplift, blue subsidence, and white no change.

Negative values (displayed in blue on this color scale) indicate either subsidence or horizontal displacement in the direction away from the sensor, but again is most often a combination of both. Areas displayed in white indicate regions without change.

Step 6: Export as GeoTIFF

1. Right-click in the view area on your masked and re-colored displacement map. Select Export View as Image, and save the file.

2. In the right-hand side of the new window (Figure 12), select Full Screen.

3. Next to Files of type select GeoTIFF.

4. Click Save.

View in Google Earth (OPTIONAL)

To export to KMZ format, the Masked Displacement band must be in a Geographic Coordinate System (lat/lon). If you output to a UTM projection during Terrain Correction in Step 3, you will need to reproject the output to WGS 84 (Figure 13). Alternatively, you can rerun Step 3 projecting to WGS 84 instead of UTM, then repeat Steps 4 and 5.

Subset Bands (OPTIONAL)

It takes a while to reproject an entire stack, so you may wish to create a subset with only the bands required for the Masked Displacement output first before reprojecting.

1. Select the final product (which includes the Masked Displacement band), and from the menu bar, navigate to Raster > Subset.

2. Select the Band Subset tab and select only the Masked Displacement, coh and displacement bands. Note that if you only select the Masked Displacement band, S1TBX pops up a window prompting you to select the reference datasets (coherence and displacement) as well.

3. Click <OK> to generate the subset. The output will be prefixed with subset and added to the Product Explorer.

Reproject Subset Bands

Figure 13: Reprojection Window

Select the subset product (or the full product including the Masked Displacement if you want to reproject all of the bands) in the Product Explorer.

1. From the menu bar, navigate to Raster > Geometric Operations > Reprojection.

2. Make sure that the source in the I/O Parameters tab is your final product, including the Masked Displacement band, and tag the output file as desired (you may wish to add an indication that it is projected to WGS84).

3. In the Reprojection Parameters tab, change the Projection to Geographic Lat/Lon (WGS 84) if necessary, and change the Resampling method to Bilinear.

4. Click <Run> to generate the reprojected output.

5. You will need to reset the color scheme of the Masked Displacement band in the output raster (see Step 5); it will revert to the default color settings in the reprojection process.

Export Masked Displacement Band to KMZ

Double-click on the final Masked Displacement band (projected to WGS84) in the Product Explorer to view the band. Zoom or pan to the desired extent for the KMZ export.

1. Right-click in the view area on your masked and re-colored displacement map. Select Export View as Google Earth KMZ, and save the file.

2. Open Google Earth in your web browser. Wait for the web application to load.

3. Click the Bookmark Icon in the toolbar along the left side of the screen. Hovering over it will reveal the label My Places.

4. Click Import KML File > Open File and select your exported displacement map. Google Earth will overlay the map and zoom to the geographic area (Figure 14).

fig 14
Figure 14: Displacement map projected on Google Earth imagery, with legend indicating displacement values. Contains modified Copernicus Sentinel data (2016) processed by ESA. Imagery © 2018 Landsat/Copernicus, Data SIO, NOAA, U.S. Navy, NGA, GEBCO. Map Data © 2018 Google, SK telecom, ZENRIN

Considerations

Uplift or Subsidence?

The sign on our displacement maps can at sometimes be ambiguous. Interpreting the direction of displacement must be done carefully with respect to the master and slave combination of your two SLCs, as well as the expression used when converting the unwrapped phase interferogram to displacement. Recall that the Sentinel-1 Toolbox uses the following formula where λ is Sentinel-1’s C-Band SAR wavelength and ΔΦd is the unwrapped phase difference between the two SLCs.

equation

Notice how this also includes a negative sign, implying that our displacement values will be opposite those of the unwrapped interferogram. This makes sense if you think about what the phase values actually mean. Our interferogram was created in the frame of reference of the satellite, meaning that the unwrapped phase values correspond to how much the distance between the surface and the satellite has changed. An increasing phase value indicates that this distance is increasing and what this actually corresponds to on the ground is subsidence. In this way, a positive unwrapped phase value will correspond with a negative displacement on the ground.

The alternative way to reach this same result is by choosing the second image in the pair as master. In this case, the phase values would be with respect to the post-event image and the sign of the phase values will correspond to the sign of the displacement. Instead of using the Sentinel-1 Toolbox’s default expression, you would have to use band maths to manually generate the displacement map, remembering to exclude the negative sign from the expression.

If you’re attempting to interpret a deformation map where you are unsure of the expression used to calculate the displacement, the best way to verify the sign on your displacement values is to compare a point to known ground truth data. If your area of study is known to follow a certain behavior such as subsidence as a result of aquifer depletion then this can also be used. Deforming volcanos and earthquake fault ruptures will produce less predictable results, however, so it’s best to use caution in these situations and consult ground truth data if it’s available.

Sentinel-1 Toolbox and SNAPHU Limitations

If you were to compare the deformation map generated in this tutorial to products generated using the same base granules with other software, you will notice some differences. The most obvious changes will manifest during the unwrapping stage. This is primarily because of the lower coherence of the Sentinel-1 Toolbox interferogram. During the unwrapping stage, decorrelated regions may cause unwrapping errors and regions of subsidence may bleed into regions where uplift actually occurred. Unfortunately, this is the case for the deformation map created in this recipe. Other software packages with more accurate co-registration processors may increase coherence.

Atmospheric Error

Interferograms can be impacted by differences in atmospheric conditions, particularly the presence of water vapor, at the time of the two acquisitions. The impacts of atmospheric error can be mitigated by using software that implements atmospheric models to correct for this difference. InSAR Time Series analysis can also be used to help reduce the impact of atmospheric error. It is important to note that atmospheric errors are still present after low coherence areas have been masked out, as atmospheric conditions only impact the phase and distance measurements without impacting coherence.

Data Recipe (Tutorials)

AllASF MapReadyArcGISCloud ComputingGAMMAGDALGMT5SARInSARQGISRadiometric Terrain CorrectionSNAPHUSentinel-1 Toolbox

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Learn more about detecting environmental change in synthetic aperture radar data using ArcGIS with this Alaska Satellite Facility Data Recipe….

How to Geocode Sentinel-1 with ArcGIS

Learn more about geocoding Sentinel-1 synthetic aperture radar data using ArcGIS with this Alaska Satellite Facility Data Recipe….



How to Create Cloud Storage Using AWS Simple Storage Service (S3)

Learn more about creating cloud storage using the Simple Storage Service (S3) in this Alaska Satellite Facility Data Recipe….

How to Configure AWS for Running the GMT5SAR InSAR Recipe

Script output images: color phase products for each swath F1, F2, F3….

How to Move files in and out of an AWS EC2 Instance – Windows

Learn more about moving files in and out of an AWS Elastic Compute Cloud instance on Windows with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script in the Cloud — Windows

Learn more about creating and unwrapping interferograms using free GMT5SAR software on Windows with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script in the Cloud — OS X

Learn more about creating and unwrapping interferograms using free GMT5SAR software on Mac OS X with this Alaska Satellite Facility Data Recipe….

How to Connect to EC2 with SSH Mac OS X

Learn more about connecting to an AWS Elastic Compute Cloud instance using SSH protocol on Mac OS X with this Alaska Satellite Facility Data Recipe….

How to Connect to your EC2 Instance using PuTTY V1.1

Learn more about connecting to an AWS Elastic Compute Cloud instance using PuTTY V1.1 on Windows with this Alaska Satellite Facility Data Recipe….

How to Create a Billing Alarm

Learn more about using Amazon Web Services to create a Billing Alarm with this Alaska Satellite Facility Data Recipe….

How to Create a Basic Elastic Cloud Compute (EC2) Instance

Learn more about using Amazon Web Services to create an Elastic Compute Cloud instance with this Alaska Satellite Facility Data Recipe….

How to Automatically Generate a Radiometrically Terrain-Corrected (RTC) Sentinel-1 Image using Cloud Computing

Learn more about generating radiometrically terrain-corrected Sentinel-1 images using cloud computing in this Alaska Satellite Facility Data Recipe….



How to Radiometrically Terrain-Correct (RTC) Sentinel-1 Data Using GAMMA Software

Learn more about radiometrically terrain-correcting Sentinel-1 data using GAMMA software with this Alaska Satellite Facility Data Recipe….



How to Geocode Sentinel-1 with GDAL

Learn more about geocoding Sentinel-1 synthetic aperture radar data using GDAL with this Alaska Satellite Facility Data Recipe….



How to Configure AWS for Running the GMT5SAR InSAR Recipe

Script output images: color phase products for each swath F1, F2, F3….

How to Create and Unwrap an Interferogram with GMT5SAR Script in the Cloud — Windows

Learn more about creating and unwrapping interferograms using free GMT5SAR software on Windows with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script in the Cloud — OS X

Learn more about creating and unwrapping interferograms using free GMT5SAR software on Mac OS X with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script

Learn more about creating and unwrapping interferograms using free GMT5SAR software with this Alaska Satellite Facility Data Recipe….



Interpreting an Unwrapped Interferogram: Creating a Deformation Map

Source: ASF Staff — Adapted from a RUS Copernicus Webinar (https://rus-training.eu/training/land-subsidence-mapping-with-sentinel-1)Level:   ■◆ Intermediate-Advanced find data pre-event sample data post-event sample data download data recipe pdf Continuing from the recipe How to Phase Unwrap an Interferogram, this final InSAR recipe will bring our unwrapped phase information out of abstraction into actual displacement units (meters)….

How to Configure AWS for Running the GMT5SAR InSAR Recipe

Script output images: color phase products for each swath F1, F2, F3….

How to Phase Unwrap an Interferogram

Learn more about phase unwrapping interferograms using the European Space Agency’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script in the Cloud — Windows

Learn more about creating and unwrapping interferograms using free GMT5SAR software on Windows with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script in the Cloud — OS X

Learn more about creating and unwrapping interferograms using free GMT5SAR software on Mac OS X with this Alaska Satellite Facility Data Recipe….

How to Create an Interferogram Using ESA’s Sentinel-1 Toolbox

Learn more about creating interferograms using the European Space Agency’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Create and Unwrap an Interferogram with GMT5SAR Script

Learn more about creating and unwrapping interferograms using free GMT5SAR software with this Alaska Satellite Facility Data Recipe….

How to Create a DEM using Sentinel-1 Data

Learn more about creating DEMs using Sentinel-1 data and the optional ASF Baseline tool with this Alaska Satellite Facility Data Recipe….



Mapear la Inundación Regional con SAR de banda L por el Espacio

Esta receta de datos de dos partes es para los usuarios quienes quieren mapear la inundaciónregional con el Radar de Apertura Sintética de banda L….

How to View Radiometrically Terrain-Corrected (RTC) Images in QGIS

Learn more about viewing radiometrically terrain-corrected images using QGIS with this Alaska Satellite Facility Data Recipe….

How to Map Regional Inundation with Spaceborne L-band SAR using QGIS

Learn more about mapping regional inundation using spaceborne L-band SAR data and QGIS with this Alaska Satellite Facility Data Recipe….

How to Detect Environmental Change using SAR Data in QGIS

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How to Geocode Sentinel-1 with QGIS 3.X

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How to Geocode Sentinel-1 with QGIS 2.18

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How to View Radiometrically Terrain-Corrected (RTC) Images in QGIS

Learn more about viewing radiometrically terrain-corrected images using QGIS with this Alaska Satellite Facility Data Recipe….

How to Radiometrically Terrain-Correct (RTC) Sentinel-1 Data Using the ESA Toolbox

Learn more about radiometrically terrain-correcting Sentinel-1 data using ESA’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Radiometrically Terrain-Correct (RTC) Sentinel-1 Data Using Sentinel-1 Toolbox Script

Learn more about radiometrically terrain-correcting Sentinel-1 data using ESA’s Sentinel-1 Toolbox script with this Alaska Satellite Facility Data Recipe….

How to Radiometrically Terrain-Correct (RTC) Sentinel-1 Data Using GAMMA Software

Learn more about radiometrically terrain-correcting Sentinel-1 data using GAMMA software with this Alaska Satellite Facility Data Recipe….

How to View Radiometrically Terrain-Corrected (RTC) Images in ArcGIS

Learn more about viewing radiometrically terrain-corrected images using ArcGIS with this Alaska Satellite Facility Data Recipe….

How to Automatically Generate a Radiometrically Terrain-Corrected (RTC) Sentinel-1 Image using Cloud Computing

Learn more about generating radiometrically terrain-corrected Sentinel-1 images using cloud computing in this Alaska Satellite Facility Data Recipe….

How to Automate a Radiometric Terrain Correction Process Chain Using a Sentinel-1 Toolbox Graph

Learn more about automating a radiometric terrain correction process chain using ESA’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….



How to Phase Unwrap an Interferogram

Learn more about phase unwrapping interferograms using the European Space Agency’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Create a DEM using Sentinel-1 Data

Learn more about creating DEMs using Sentinel-1 data and the optional ASF Baseline tool with this Alaska Satellite Facility Data Recipe….



Interpreting an Unwrapped Interferogram: Creating a Deformation Map

Source: ASF Staff — Adapted from a RUS Copernicus Webinar (https://rus-training.eu/training/land-subsidence-mapping-with-sentinel-1)Level:   ■◆ Intermediate-Advanced find data pre-event sample data post-event sample data download data recipe pdf Continuing from the recipe How to Phase Unwrap an Interferogram, this final InSAR recipe will bring our unwrapped phase information out of abstraction into actual displacement units (meters)….

How to Phase Unwrap an Interferogram

Learn more about phase unwrapping interferograms using the European Space Agency’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Radiometrically Terrain-Correct (RTC) Sentinel-1 Data Using the ESA Toolbox

Learn more about radiometrically terrain-correcting Sentinel-1 data using ESA’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Radiometrically Terrain-Correct (RTC) Sentinel-1 Data Using Sentinel-1 Toolbox Script

Learn more about radiometrically terrain-correcting Sentinel-1 data using ESA’s Sentinel-1 Toolbox script with this Alaska Satellite Facility Data Recipe….

How to Generate a Subset from the Mosaic of Two Sentinel-1 Products in the Same Swath

Learn more about generating a subset from the mosaic of two Sentinel-1 products in the same swath using the Sentinel-1 Toolbox with this ASF Data Recipe….

How to Create an Interferogram Using ESA’s Sentinel-1 Toolbox

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How to Create a Subset of a Sentinel-1 Product

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How to Create an RGB Composite from Multi-Temporal Sentinel-1 Data

Learn more about creating an RGB composite using ESA’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Generate a Mosaic of Two Sentinel-1 Products in Adjacent Paths

Learn more about generating a mosaic of two Sentinel-1 products in adjacent paths using the Sentinel-1 Toolbox with this ASF Data Recipe….

How to Create a DEM using Sentinel-1 Data

Learn more about creating DEMs using Sentinel-1 data and the optional ASF Baseline tool with this Alaska Satellite Facility Data Recipe….

How to Automate a Radiometric Terrain Correction Process Chain Using a Sentinel-1 Toolbox Graph

Learn more about automating a radiometric terrain correction process chain using ESA’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Create Glacier Velocity Maps with Sentinel-1 Toolbox

Learn more about creating glacier velocity maps to estimate glacier motion using the Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….

How to Map Regional Inundation with Sentinel-1 using Sentinel-1 Toolbox

Learn more about mapping regional inundation using Sentinel-1 data and ESA’s Sentinel-1 Toolbox with this Alaska Satellite Facility Data Recipe….


GIS Tools

ASF ArcGIS Toolbox

The ASF_Tools ArcGIS Python Toolbox can be used with either ArcGIS Desktop or ArcGIS Pro, and contains tools that perform geoprocessing tasks useful for working with Synthetic Aperture Radar (SAR) data. The tools were designed to be used with Sentinel-1 Radiometric Terrain Corrected (RTC) SAR datasets, such as those available on-demand using ASF’s Data Search-Vertex portal, but several of the tools have the potential to be used with a variety of rasters, including non-SAR datasets.

The Toolbox is distributed as a zipped archive including the .pyt Toolbox script and associated .xml files. There is an XML file for the toolbox itself and one for each of the tools it contains. These XML files contain the metadata displayed in the item descriptions and tool help windows, and must be kept in the same directory as the Python Toolbox (.pyt) file, or the information they contain will no longer be accessible to ArcGIS.

Toolbox Contents

Unzip Files Tool
This tool assists in file management when downloading .zip files from ASF. It could be used to extract to a specified location any zip files with an additional internal directory containing the individual files. The tool deletes the original zip files once they are extracted, and is especially helpful when dealing with file paths that are so long that they are beyond the maximum allowed in default Windows unzip utilities.

Scale Conversion Tool
This tool converts pixel values in calibrated SAR datasets (such as RTC rasters) from power or amplitude scale into power, amplitude or dB scale. This is an application specific to SAR data values/scales.

Reclassify RTC Tool
This tool generates a raster that includes only those pixels below a user-defined threshold value, and is designed for isolating water pixels. While intended for RTC files in dB scale, this tool could be used for any application where the user is interested in generating a spatial mask for values below a given threshold in a single-band raster.

Log Difference Tool
This tool compares two rasters by calculating the log difference on a pixel-by-pixel basis to identify areas where backscatter values have changed over time. While intended for RTC files in amplitude scale, this tool could be used to compare the pixel values of any two single-band rasters, as long as there are no negative values (NoData values will be returned for pixels with a negative number in either of the datasets).

RGB Decomposition Tool
This tool generates an RGB image using the co- and cross-polarized datasets from an RTC product. Input datasets can be in either amplitude or power scale, and the primary polarization can be either vertical (VV/VH) or horizontal (HH/HV). Visit https://github.com/ASFHyP3/hyp3-lib/blob/develop/docs/rgb_decomposition.md for more information about interpreting RGB Decomposition images and the processing steps used to generate the color values.

Prerequisites

Users must have either ArcGIS Desktop (ArcMap) or ArcGIS Pro installed and licensed on their computer. The Toolbox has been tested with Desktop versions 10.6.1 and 10.7.1 and Pro versions 2.4.2, 2.5.x and 2.6.1, but it may work with earlier versions as well.

Note that several of the tools require the Spatial Analyst extension. Users who do not have licensing for this extension in ArcGIS will not be able to use many of the included tools.

To install the Toolbox

  • Download the zip file and extract the contents to any directory accessible by the computer running ArcGIS.
  • Ensure that the Spatial Analyst extension is licensed and enabled.

ArcGIS Desktop (ArcMap)

  • Click on the Customize menu in ArcMap and select Extensions…
  • Check the box next to Spatial Analyst and click the Close button at the bottom of the Extensions window.
    • If you are unable to check this box, you do not have access to the Spatial Analyst extension and will not be able to make use of tools requiring this extension.

ArcGIS Pro

  • Click on the Project tab and select the Licensing tab.
  • In the list of Esri Extensions, scroll down to verify that the Spatial Analyst is licensed and enabled.
    • If it is not, an organization administrator will need to enable the extension in your user account.
    • If your organization does not have a license available for you to use, you will not be able to make use of tools requiring this extension.

Using the Toolbox

In the ArcMap Catalog window or the ArcGIS Pro Catalog pane/view, navigate to the directory containing the toolbox (create a new folder connection if necessary).

  • To open the Catalog window in ArcMap, click on the Windows menu and select Catalog.
  • To open the Catalog pane or view in ArcGIS Pro, click the View tab and click on either the Catalog Pane or Catalog View button.

Note that if you explore the extracted contents of the zip file outside of the ArcGIS environment, the directory will contain one .pyt file and a number of .xml files.

In the ArcGIS Catalog window/pane/view, only the Toolbox is displayed, and when it is expanded, all of the Tools contained in the Toolbox script are displayed. The XML files are automatically referenced when ArcGIS requires the information they contain, and do not appear as additional files in the ArcGIS Catalog environment. The XML files must remain in the same directory as the .pyt file, and their filenames should not be changed.

  • Double-click the ASF_Tools.pyt file to display the Tools (Scripts) included in the toolbox.
  • Double-click on a Tool (displayed with a Script icon) to launch the dialog box or geoprocessing pane, as you would for any other ArcGIS Tool/Script.
  • Enter the parameters as prompted and click the OK button to execute the tool.

Note that output products are not automatically added to a project by default. You must navigate to them in the Catalog window/pane/view (or using the Add Data dialog) and add them to your project if desired.

Tool Help

The XML files included in the zip file are accessed when a user views the metadata for the toolbox, individual tools, or even different fields within the tool dialog.

Accessing Help from within the Tool Dialog Box

ArcGIS Desktop

  • Click on the Show Help button at the bottom of the tool window to open the help panel.
    • This panel will display information about the tool in general if no field is activated.
    • If the user clicks on any of the parameter fields, information specific to that parameter will be displayed.
  • Click on the Tool Help button at the bottom of the Help pane to open another window that displays most of the information that would be displayed in the tool’s Item Description.

ArcGIS Pro

  • When you hover over any of the parameter fields in the tool dialog, a blue i appears. Hover over or click the blue i icon to view helpful tips specific to that parameter.
  • Hover over the blue question mark at the top of the geoprocessing pane to display information about the tool. Click on it to open the full tool description in a browser window.

Accessing Help from the Catalog Interface

ArcGIS Desktop

ArcCatalog displays the information contained in the xml metadata files in the Description tab for the toolbox and each tool.

In the ArcMap Catalog window, the Item Description for the toolbox or any of its constituent tools displays the xml content.

  • Right-click the toolbox or tool in the Catalog window and select Item Description to view the information.

ArcGIS Pro

The xml metadata is displayed in the Metadata tab in the Catalog view.

  • Right-click a tool in the Catalog pane and select View Metadata to open the Metadata tab for the item in the Catalog view.
    OR
  • Open the Catalog View directly to navigate to the tool and select the Metadata tab.

Current Release Information

ASF GIS Tools Release Notes

Contact ASF if you have questions about the Toolbox, or if you have suggestions for other tools to include.

Vertex Getting Started User Guide

Geographic Search Options

  • The Vertex map defaults to Satellite View
  • Navigate to your area of interest by dragging the map while holding down the left mouse button.
  • By default, the map-drawing tool is a bounding box. Click on the map once to specify the starting corner, move the mouse, then click again to finish the box. Additional drawing tool options are available in the toolbar at the top of the screen, including point, linestring, and polygon options.
    • Point allows you to define an area of interest by clicking on the map to place a point.
    • Line allows you to define an area of interest over a series of line segments by clicking on the map multiple times. Double-click to stop adding segments.
    • Polygon allows you to define an area of interest over an arbitrary polygon. You will receive an error message at the bottom of the window if there was a problem with the polygon (self-intersecting, reversed polygon winding order, etc.).
    • Box allows you to define an area of interest over a lat/long-aligned bounding box by clicking once to set one corner, and again to set the opposite corner.
    • Once a shape has been drawn, select the Edit current area of interest icon on the toolbar to move, add, and delete points. Select the Draw new area of interesticon to create a new AOI.
  • Dataset enables you to choose the dataset of interest.
    • If you need more information about a particular dataset, click on the appropriate icon in the Dataset selector.
  • Area of Interest gives you the option of importing an area of interest as a geospatial file or by entering a set of geographic coordinates.
    • Click on the down arrow next to Area of Interest in the top menu
    • Click the Import Area of Interest button in the Options window
    • Click Select Files and navigate to a folder on your computer, or drag and drop files into the box. GeoJSON, shapefiles, and KML files are supported provided they are in a latitude/longitude-based coordinate system, such as WGS84.
      • When importing a GeoJSON file, all geometries in the file will be included. If multiple geometries are found, a convex hull will be used to represent them in the search.
      • Shapefiles can be either a single .shp file, multiple shapefile components (.shp, .shx, .dbf), or a zip file containing one or more shapefile components. At a minimum, the .shp component must be included in all cases.
    • An area of interest may also be defined by a set of coordinates entered in the Options window.
      • Coordinates should be entered as decimal degrees in well-known text (WKT) format. Coordinates entered as a comma-separated long/lat string (e.g. -97.38,36.46,-53.44,36.46…) will be automatically converted by Vertex to WKT format.
    • You can save the coordinates of a search so they can be used to exactly recreate an area of interest in later searches.
      • Once the Area of Interest has been set, mouse over the coordinates. A Copy to clipboard icon will appear. Click on the icon and paste the coordinates into a new search or to a text file for later use.
      • Note: See the section Other Vertex Options for additional ways of saving searches.
    • At any time you can clear your search area by clicking on the Trash can icon in the top menu bar. 
  • Filters… enables you to further refine your search
    • Date Filters  Search dates are optional, so they default to empty.  If you are searching for specific dates, you can define the date range further in the Start Date and End Date fields. The date picker will automatically constrain your selection to a valid range for the selected dataset.
      • Note: this information may also be found by clicking on for a dataset.
      • Seasonal Search allows constraining the search to certain annual periods within an overall range of dates.  Click the Seasonal Search toggle and additional options will appear, allowing you to enter an overall date range (Start Date/End Date) and the seasonal range (Season Start Day/Season End Day).
    • Additional Filters allow for additional parameters to be applied to narrow your search and reduce the number of results. Not all filters will be available for all datasets.
      • File Type – Limit the search to specific types of files. Multiple selections allowed.
      • Beam Mode – Limit the search to specific beam modes. Multiple selections allowed.
      • Polarization – Limit the search to specific polarizations. Multiple selections allowed.
      • Direction – Limit the search to a specific orbit direction.
      • Subtype – Limit the search to a specific mission spacecraft.
    • Path and Frame Filters are available for select datasets. You may enter a single path or frame, or a range. Due to inconsistent Sentinel-1 framing, we recommend searching for a frame of interest by ±1-2 frames.
  • Once all parameters have been chosen, click SEARCH. Search results will appear in the footer area of the Vertex window, and on the map.
    • Note: The number of files that are predicted to match the current search parameters is displayed under the SEARCH button. If there are no predicted matches, the search button will be greyed out and display NO RESULTS.

List Search Options

  • Selecting List Search opens the List Search window and allows you to enter a list of scenes or file names.
    • Scene allows searching for specific scene names (granule names), and the results will include any files that are part of those scenes.
    • File allows searching for specific file names (product names), and the results will only include exactly those files.
  • Edit List – Opens the List Search window so you can make changes to your list
  • Once all parameters have been chosen, click SEARCH. Search results will appear in the footer area of your browser window, and on the map.
    • Note: The number of files that are predicted to match the current search parameters is displayed under the SEARCH button. If there are no predicted matches, the search button will be greyed out and display NO RESULTS.

Baseline Search Options

  • Selecting Baseline Search provides a space to enter the name of a Master Scene, and will then search for all secondary scenes that match the coverage area of the Master.
    • Note: If there are no matching scenes, the RESULTS button will be greyed out and display NO RESULTS.
  • Once a Master Scene has been entered, click SEARCH. Search results will appear under the map. Clicking on the Zoom to results icon  at the top of the left results column will display the location of the stack of scenes on the map.
  • The graph displays the Temporal and Perpendicular (spatial) relationship of the secondary scenes to the Master.
  • Clicking on  above the graph will open the Baseline Search window. Using the sliders, the Temporal and Perpendicular extents can be adjusted to limit the number of secondary scenes displayed in the results.

Search Results

  • In Vertex, a scene is considered to be a package containing all files, or products, that are related to a specific location and time.
    • For example, the column on the left of the Results panel displays the scenes returned from a search. The column on the right displays the file contents of each scene.
  • The maximum number of files that a search will return is displayed under the SEARCH button.
    • This number can be adjusted by clicking on the down arrow.  
    • The total number of files that match the search parameters is also displayed.
  • The Scenes column (left).
    • Click on the cart icon next to a scene name to add all the scene’s files to the download queue. The cart changes appearance when this is done.
    • Click on the zoom icon next to a scene name to zoom-in to the scene’s location on the map.
  • To view more information about a scene, click on the scene in the left column and the Scene Detail and Files columns will populate.
    • The Scene Detail column (center) provides a more detailed description of the scene, including Start Date/Time, Beam Mode, Path, Frame, Flight Direction, Polarization, Absolute Orbit, and a browse image (if available). Not all scenes will have all the extra information.
      • The Baseline Tool button opens the ASF Baseline Tool, which is used for creating InSAR stacks.
      • The SBAS Tool button opens the ASF SBAS Tool, which is another method of creating InSAR stacks.
      • The Citation button opens a new window with citation guidance for published works using data, imagery, or tools accessed through ASF.
      • The More Like This button creates a search based on the selected scene’s path and frame.
    • The Files column (right) displays a list of files available for the currently selected scene. You may download files immediately or add them to your download queue by clicking on the appropriate icon.
      • Clicking on the right arrow  in front a file (product) name will expand the file to show the ancillary files included. These files may be downloaded individually or added to the download queue.
        • Notes:
          1) You must be logged in to Vertex for this feature to work.
          2) This feature is not available for all datasets.

Downloads Queue

  • Clicking on the cart icon in the header, labeled Downloads, will display the contents of your current download queue.
    • Within the download queue, the list of files you have selected to download is displayed with some basic information on each file, such as file type and size.
      • File IDs (names) can be copied
      • Files can be individually downloaded
      • Items can be removed from the queue
    • Clear will clear all files from the queue. The option Restore will be displayed to allow you to undo this action.
    • Copy File IDs will copy the file names of all files in the queue for use elsewhere. For example, this list could then be pasted into the List Search window.
    • Data Download – Is used to download multiple products, with either the Download Python Script (.py) option or Metalink (metalink) file option.
    • Metadata Download – Is used to export the contents of the download queue to a CSV, KML, or GeoJSON file. The KML and GeoJSON files provided by this feature are compatible with the Geographic Search Import feature.

Other Vertex Options

  • Click on the three-bars menu icon next to the Sign in icon to display the menu options.
    • Copy Search Link will copy all the search parameters that have been set in the current search as a URL. The URL can then be pasted into a browser search bar to recreate the search exactly, or pasted into a document and saved to recreate the search later.
    • Share With Email will open a new email with the URL of the search to send to others.
    • Help & Tutorials provides both illustrated and video demonstrations on the basic steps for setting up a search and viewing the results.
    • What’s New provides updated information on new features and changes that have been added to Vertex for improved performance and functionality.
  • Click on the down arrow on the Search
    • Clear Search will clear all search parameters that have been set except for Search Type and Dataset.
    • Save Search* allows you to name and save all current search parameters in Saved Searches.
    • Saved Searches…* opens a list of searches that you have named and saved. Click on the icon to load the search settings.
    • Search History…* opens a list of your 10 last searches that were not named and saved. Click on the  icon to load the search settings.
    • Help & Tutorials provides both illustrated and video demonstrations on the basic steps for setting up a search and viewing the results.
      • *Note: You must be logged in to Vertex for these options to be available.
Script output images: color phase products for each swath F1, F2, F3. Contains modified Copernicus Sentinel data (2015) processed by ESA.

How to Configure AWS for Running the GMT5SAR InSAR Recipe

Script output images: color phase products for each swath F1, F2, F3. Contains modified Copernicus Sentinel data (2015) processed by ESA.

Adapted from instructions prepared by C. Stoner, ASF

Easy (AWS sign-up and configuration)

Background

After logging-in the user must make some choices before creating their InSAR products. These steps guide you through that process, with recommended settings.

Steps

Start an EC2 Instance

    1. Sign in to your AWS account, or create one now.
AWS Management Console
    1. Click on the Services drop down on the top left
    2. Under Compute, click on EC2.
Navigate to EC2

Select an Amazon Machine Image (AMI) — i.e., the software package you want

    1. At the right on the top menu bar, set the Region to US East (N. Virginia) by selecting from the drop-down menu. 
    2. Click on the Launch Instance button.
    3. Click on Launch Instance.
Select the Region and Launch Instance
    1. Choose an Amazon Machine Instance (AMI) — Step 1
      • (1) Under Quick Start, click on Community AMIs.
      • (2) In the Search community AMIs box, type “asf-insar-gmt5sar” and press Enter.
      • (3) Click the Select button next to ASF-INSAR-GMT5SAR
Search Community AMIs for asf-insar-gmt5sar
Select the ASF-INSAR-GMT5SAR AMI

Configure the EC2 Resources

    1. Choose an Instance Type — Step 2
      • Scroll down the table of available instances and choose: m4.xlarge.
        • Then click on the Next: Configure Instance Details button.
    2. Configure Instance Details — Step 3
      • Nothing needs to be changed here, so click on the Next: Add Storage button.
Choose Instance Type m4.xlarge
View Instance Details
    1. Add Storage — Step 4
      • The volume storage size is preset, so confirm that the Size (GiB) value is 230 and then click on the Next: Add Tags button.
Set Size value, then click Next: Add Tags
    1. Add Tags — Step 5
      • (1) Click on the Add Tag button.
      • (2) Under Key, type “Name.”
      • (3) Under Value, type a description; for example, “asf-insar-tutorial.”
      • Click on the Next: Configure Security Group button.
Click Add Tag
Enter text for the Key and Value entries
    1. Configure Security Group — Step 6
      • This step allows you to set access permissions for your instance. We will create a setting so that only your computer can access your instance.
      • In the Security group name box, type a name.
      • Under Source, click on Custom and select and click on My IP.
      • The IP address of your computer is automatically selected.
      • Click on the Review and Launch button.
Enter a Security group name and choose a Source
Select My IP as a Source
    1. Review Instance Launch — Step 7
      • This last step allows you to review the details of your configuration before activating your new instance.
        • A warning is displayed at the top of the screen that can be ignored. The “free usage tier” AMIs offered in AWS are not powerful enough to process the GMT5SAR InSAR recipe.
      • Click on the Launch button.
Review the details of your configuration

Create a Key Pair (.pem file)

    1. Create a key pair for authentication and encryption when connecting to your running EC2 Instance. Read more on information about key pairs.
      • Click on Choose an existing key pair and select Create a new key pair.
      • Name the key pair; for example, asf_tutorial_keypair.
      • Click on the Download Key Pair button.

Note: The key pair file will download to your default Download directory as filename.pem and can be moved to a directory of your choice. The .pem file is required to connect to your EC2 Instance and to transfer data between your computer and your EC2 Instance.

Select Create a new key pair
Download your Key Pair

Launch the Instance

    1. After creating the key pair, click on the Launch Instances button.
    2. The Launch Status window provides information on your new EC2 Instance. To view your instance, scroll to the bottom of the page and click on the View Instances button.
View Launch Status
View your EC2 Instance's details

Terminate the Instance

Important: Do not terminate your EC2 Instance until you have finished processing and moved any files you want to save from your instance to your computer. To connect to your EC2 Instance and move files in or out, refer to the ASF Data Recipes: How to Connect to an AWS EC2 Instance — OS X and How to Connect to an AWS EC2 Instance using PuTTY v1.1 (Windows)

    1. Once you have launched your instance, you will start incurring charges on your account.
    2. When you have finished processing, you need to terminate the EC2 instance to avoid incurring additional charges.
      • From the EC2 Dashboard, navigate to Actions > Instance State.
        • Click on Terminate and confirm.
        • This deletes the instance and all data stored on the instance; a new AMI will need to be configured for any future processing.

Important: Selecting Stop will shut the instance down and stop further EC2 charges from accruing. But you will continue to be charged for the data left in the instance EBS storage volume (e.g., the GMT5SAR script, granule files, PRODUCT files, etc.) The advantage of this option is that you can restart the instance and avoid configuring a new one for additional processing. 

Note: Each time an instance is started, a minimum one minute is charged. After one minute, you are charged by the seconds used.

Navigate to terminate the EC2 Instance