envi classic topsar data and dem analysis - exelis visual

ENVI Classic Tutorial:TOPSAR Data and DEMAnalysis

TOPSAR Data and DEM Analysis 2Files Used in this Tutorial 2Background: TOPSAR Data 2

Display and Convert TOPSAR Data 3View TOPSAR Header 3Load and Display Raw C-Band Image 3Load and Display Raw DEM Image 4Convert Data Units 5Synthesize P- and L-Band Data 7

Analyze Polarimetric SAR Data 9Display Multi-Frequency, Polarimetric SAR Images 9Examine Polarization Signatures 9Pedestal Height Image 11

Display and Analyze DEMs 13Display Converted DEM 13Exclude Bad DEM Values 13X and Y Elevation Profiles 14Arbitrary Elevation Transect 15Density Slice the DEM 16Overlay Elevation Contours 18View 3D Perspective andOverlay Image 19Smooth the DEM 20Generate Topographic Modeling Images 21Generate Topographic Feature Image 22

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TOPSAR Data and DEM AnalysisThis tutorial uses polarimetric synthetic aperture radar (SAR) data and a digital elevation model (DEM)of Tarrawarra, Australia, generated from NASA Jet Propulsion Laboratory's (JPL's) TopographicSynthetic Aperture Radar (TOPSAR) instrument, flown aboard a NASA DC-8 aircraft. The tutorialdemonstrates input and display of the TOPSAR data and display and analysis of the TOPSAR DEMusing standard tools in ENVI® Classic. For the DEM, these include data input; gray scale and color-density-sliced display; generation and overlay of elevation contours; use of ENVI Classic’s X, Y, andarbitrary profiles (transects) to generate terrain profiles; 3D perspective viewing and image overlay; andgeneration of topographic modeling and feature images.

Files Used in this TutorialDownload data files from the Exelis website.

File Descriptionts0218_c.vvi C-Band VV-polarization image, integer formatts0218_c.cor C-Band correlation imagets0218_c.dem C-Band DEM imagets0218_c.inc C-Band incidence angle imagets0218_l.dat L-Band Stokes matrix datats0218_p.dat P-Band Stokes matrix data

Background: TOPSAR DataA full TOPSAR dataset from JPL includes polarimetric (quad-polarized) data for both P- and L-bandsand a C-band VV-polarization image. JPL generates a DEM from SAR interferometry using the C-bandantenna. Also provided are the correlation image and an incidence angle image generated from the C-band data.


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Display and Convert TOPSAR DataIn this section of the tutorial, you will display TOPSAR data and convert them to physical parameters.

View TOPSAR Header1. From the ENVI Classic main menu bar, select Radar > Open/Prepare Radar File > View

AIRSAR/TOPSAR Header. An AIRSAR/TOPSAR Input File selection dialog appears.

2. Select ts0218_c.vvi. The AIRSAR File Information dialog appears, listing information fromthe embedded AIRSAR Integrated Processor headers.

3. Review the New Header, Parameter Header, and the Calibration Header sections.

4. Repeat Steps 2-3 for the DEM file ts0218_c.dem. View the TOPSAR DEM Header in placeof the Calibration Header.

5. Close the AIRSAR File Information dialog when you are finished.

Load and Display Raw C-Band Image1. From the ENVI Classic main menu bar, select Radar > TOPSAR Tools > Open TOPSAR File.

A file selection dialog appears.

2. Select ts0218_c.vvi and click Open. This opens and displays the TOPSAR C-Band datawithout converting to physical units (sigma zero), utilizing the embedded TOPSAR header to getthe required file information. This also loads the image into the Available Bands List.

You could also open this file by selecting File > Open External File > Radar > TOPSAR, or byselecting File > Open Image File, but you have to manually enter the file parameters with thelatter option.

3. In the Available Bands List, select the Gray Scale radio button, and click Load Band to load theimage.


4. Examine the geometry and characteristics of the image. Double-click inside the Image window tostart the Cursor Location/Value tool. This is a ground-range, C-Band, VV-polarization imagescaled to integer format. A scaling factor must be applied to the data to convert to sigma zero(radar backscatter coefficient).

5. Observe the general magnitude of the pixel values.

Load and Display Raw DEM Image1. From the ENVI Classic main menu bar, select Radar > TOPSAR Tools > Open TOPSAR File.

A file selection dialog appears.

2. Select ts0218_c.dem and click Open. This opens the TOPSAR DEM data, utilizing theembedded AIRSAR/TOPSAR header to get the required file information.

You could also open this file by selecting File > Open Image File, but you have to manually enterthe file parameters.

3. In the Available Bands List, click Display #1 and select New Display. Click Load Band. TheDEM image appears in a display group:


4. Double-click inside the Display #2 Image window to start the Cursor Location/Value tool.Observe the general magnitude of the integer pixel values, which are in units of raw digitalnumbers (DNs), as stored in the DEM file.

5. From a Display group menu bar, select Tools > Link > Link Displays. The Link Displays dialogappears. Click OK to link the two images. Click in an Image window to toggle between the twoimages.

Convert Data Units1. From the ENVI Classic main menu bar, select Radar > TOPSAR Tools > Convert TOPSAR

Data. An Enter TOPSAR Filename dialog appears.

2. Select ts0218_c.vvi and click Open. A TOPSAR Conversion Parameters dialog appears.ENVI Classic automatically identifies all of the TOPSAR data based on the TOPSAR file-naming convention. The VV Polarization, Correlation, Incidence Angle, and DEM images areopened. The C-VV data are automatically converted to sigma zero, and DEM data are convertedto meters based upon values in the TOPSAR headers.

3. Click Spatial Subset and enter 1061 in the Line/To field. This will match the size of the C-banddata and DEM to the P- and L-band data. Click OK.


4. In the Enter Output Filename field of the TOPSAR Conversion Parameters dialog, entertopsar.img and click OK. Four images are added to the Available Bands List: VVPolarization, Correlation, Incidence Angle, and DEM (m).

5. In the Available Bands List, click Display #2 and select New Display.

6. Load the C-VV sigma zero image by selecting the VV Polarization band name and clickingLoad Band.

7. Double-click in the Display #3 Image window to start the Cursor Location/Value dialog. Observethe general magnitude of the pixel values (sigma zero).

8. From a Display group menu bar, select Tools > Link > Link Displays. The Link Displays dialogappears.

9. Click the Display #2 (DEM) toggle button to select No. Click OK to link Display #1 and Display#3 (the two C-VV images). Compare the raw and sigma zero images.

10. In the Available Bands List, click Display #3 and select New Display.

11. Select DEM (m) and click Load Band.

12. Observe the general magnitude of the pixel values, which represent elevations in meters. Note thelarge negative number (-2911.099854) associated with holes in the DEM and the image border.These are not valid elevations and should be excluded from analysis using masking functions. Youwill perform this step on Page 10.

13. From a Display group menu bar, select Tools > Link > Link Displays. Link the two DEM imagesby toggling the display options in the Link Displays dialog as follows. Click OK.

14. When you are finished comparing images, selectWindow > Close All Display Windows.


Synthesize P- and L-Band DataBoth the L-Band and P-Band data are distributed by JPL in compressed Stokes matrix format, which youcannot directly view. ENVI Classic provides utilities to decompress the data and synthesize them toimage format.

1. From the ENVI Classic main menu bar, select Radar > Open/Prepare Radar File > SynthesizeAIRSAR Data. (This menu option also applies to TOPSAR data.) An Input Stokes Matrix Filesdialog appears.

2. Click Open File and select ts0218_l.dat. The L- and P-band Stokes matrix filenames appearin the Input Stokes Matrix Files dialog.

3. Click OK. The Synthesize Parameters dialog appears. The “standard” polarization bands, L-HH,L-VV, L-HV, L-TP (total power); P-HH, P-VV, P-HV, and P-TP (total power), are automaticallyentered into the dialog. If you want additional polarizations, enter the Transmit and ReceiveEllipticity and Orientation angles into the appropriate text boxes in the upper-left part of the dialogand click Add Combination.

4. Click the Output Data Type drop-down list and select Byte.

5. In the Enter Output Filename field, enter ts0218lp.syn. Click OK to synthesize theimages.

6. In the Available Bands List, select one or more of the synthesized bands to display as a grayscaleor an RGB image.

7. Compare the L-Band and C-Band VV data using image linking and dynamic overlays. Below is aportion of the P-Band VV image with a Gaussian stretch applied to highlight features.


8. When you are finished, close Display #1.


Analyze Polarimetric SAR DataENVI Classic provides a full suite of tools for analyzing polarimetric SAR data. These includegeneration and display of specific polarization images, a phase image, and a pedestal height image, aswell as extraction of polarization signatures and generation of a scattering classification image.

Please see the Basic SAR Processing and Analysis and Polarimetric SAR Processing and Analysistutorials for more information on general SAR analysis functions such as extracting polarizationsignatures, adaptive filters, and edge enhancement.

The following exercises are similar to those in the Polarimetric SAR Processing and Analysis tutorial,but they use TOPSAR data instead of SIR-C data.

Display Multi-Frequency, Polarimetric SAR ImagesThe synthesized images you produced earlier form the basis for analyzing polarimetric data.

1. In the Available Bands List, select [L-HH] under ts0218lp.syn and click Load Band.

2. From the Display group menu bar, select Tools > Animation. An Animation Input Parametersdialog appears.

3. Hold down the Ctrl key and click the two total power images [L-TP] and [P-TP] to deselectthem. Click OK.

4. Observe the different frequencies and polarizations, and compare the SAR response for variousmaterials to determine a three-band combination that will maximize spectral contrast.

5. When finished, select File > Cancel from the Animation Input Parameters dialog menu bar.

6. View a multi-frequency, multi-polarization TOPSAR image as an RGB composite. In theAvailable Bands List, select the RGB Color radio button and select your preferred bands fromStep 4. Click Load RGB.

Or, you can view the P-HH, L-HH, and C-VV bands as an RGB composite.

7. Observe the color differences associated with various materials. Experiment with differentcontrast stretches based on the Image and Zoom windows to maximize color differences in theimage.

Examine Polarization SignaturesPolarization signatures are 3D representations of the complete radar scattering characteristics of thesurface for a pixel or average of pixels. They show the backscatter response at all combinations oftransmit and receive polarizations and are represented as either co-polarized or cross-polarized. Co-polarized signatures have the same transmit and receive polarizations. Cross-polarized signatures haveorthogonal transmit and receive polarizations. Polarization signatures are extracted from the compressedscattering matrix data using the ROIs for pixel locations.


These signatures can be used to observe the scattering characteristics of materials and surfaces and todetermine what polarization images to generate to maximize image contrast between materials asviewed in the SAR data.

1. Move the cursor in the Image window to an area that appeared to change significantly in theanimation.

2. From the Display group menu bar, select Tools > Polarization Signatures > AIRSAR. (Thismenu option also applies to TOPSAR data.) The L- and P-band Stokes matrix filenames appear inthe Input Stokes Matrix Files dialog.

3. Click OK. The Polarization Signature Viewer dialog appears.

4. From the Polarization Signature Viewer dialog menu bar, select Options > Extract CurrentPixel to extract an L-Band polarization signature for the current pixel.

5. Select Frequency > P to display the corresponding P-Band polarization signature.

6. From the Polarization Signature Viewer dialog menu bar, select Polsig_Data to see the differentsurface plotting options. Select Polsig_Data > Cross-Pol to display and compare the cross-polarized signature.

7. Use the left mouse button to drag a 2D cursor on the polarization signature image on the right sideof the plot. Note the corresponding 3D cursor in the polarization plot. Observe the maximumcontrast orientation and ellipticity angles in the plot, and optionally synthesize and display animage with these parameters as described above.


8. Click-and-drag any axis to rotate the polarization signature.

9. Close the Polarization Signature Viewer and the display group when you are finished.

Pedestal Height Image1. Generate a pedestal height image for the TOPSAR data by selecting Radar > Polarimetric

Tools > Pedestal Height Image > AIRSAR. (This menu option also applies to TOPSAR data.)The Input Stokes Matrix Files dialog appears.

2. Click OK. A Pedestal Height Image dialog appears.

3. In the Enter Output Filename field, enter ts_ped.img. Click OK.

4. In the Available Bands List, select the Gray Scale radio button, select L-Pedestal Height underts_ped.img, and click Load Band. This image provides a measure of the amount of multiplescatter of the radar wave for every pixel, by averaging the following four polarizationcombinations:

l Orientation 0 degrees, Ellipticity –45 degrees

l Orientation 90 degrees, Ellipticity –45 degrees


l Orientation 0 degrees, Ellipticity 45 degrees

l Orientation 90 degrees, Ellipticity 45 degrees

A higher pedestal height value in the image indicates greater multiple scattering, generally arougher surface.

5. Double-click in the Image window to start the Cursor Location/Value tool, and examine thepedestal height values for this image. The figure below shows a portion of the L-band pedestalheight image.

6. Now view the pedestal height image for the P-band.

7. When you are finished, close the display group(s).


Display and Analyze DEMsThis section of the tutorial describes ENVI Classic’s tools for processing and analyzing DEMs. Whilethis tutorial refers specifically to the TOPSAR DEM, all of the methods and tools are applicable to anyDEM.

Display Converted DEM1. In the Available Bands List, click the Gray Scale radio button, select DEM (m) under

topsar.img (which you created in "Convert Data Units" on page 5), and click Load Band.

2. Double-click inside the Image window to start the Cursor Location/Value tool, and examine thepixel values of the DEM.

When you converted the DEM units to meters (see "Convert Data Units" on page 1), ENVIClassic applied a scaling function based on a formula in the AIRSAR Integrated ProcessorDocumentation, version 0.01, May 1995. The required information for this conversion is obtainedfrom the TOPSAR DEM header, specifically, an ELEVATION INCREMENT of 0.1 and anELEVATION OFFSET of 365.6.

Exclude Bad DEM ValuesNote the black areas in the upper-left part of the DEM image. These bad pixels (radar shadows in theDEM) are assigned a value of -2911.099854. You can build and apply a mask to the DEM to set thesevalues to 0.

Build Mask1. From the ENVI Classic main menu bar, select Basic Tools > Masking > Build Mask. A Mask

Definition dialog appears.

2. Select Display #1 and click OK. A Mask Definition dialog appears.

3. From the Mask Definition dialog menu bar, select Options > Import Data Ranges. An input fileselection dialog appears.

4. Click the toggle button to choose Select by Band.

5. Select DEM (m) under topsar.img and click OK. An Input for Data Range Mask dialogappears.

6. In the Data Min field, enter -2912.

7. In the Data Max field, enter -2910. Click OK.

8. From the Mask Definition dialog menu bar, select Options > Selected Areas "Off".

9. Select the Memory radio button and click Apply, followed by Cancel. The new mask bandappears in the Available Bands List.


Apply Mask1. From the ENVI Classic main menu bar, select Basic Tools > Masking > Apply Mask. An Apply

Mask Input File dialog appears.

2. Click the toggle button to choose Select by Band.

3. Select DEM (m) under topsar.img.

4. Click Select Mask Band. A Select Mask Input Band dialog appears.

5. Select the band namedMask Band and click OK. Click OK in the Apply Mask Input File dialog.An Apply Mask Parameters dialog appears.

6. In the Enter Output Filename field, enter topsar_cor.img. Click OK.

7. In the Available Bands List, selectMask under topsar_cor.img and click Load Band.

8. Use the Cursor Location/Value tool to examine the data values. The bad pixels should have avalue of 0 now.

X and Y Elevation ProfilesENVI Classic provides tools for extracting elevation profiles along the x or y directions.

1. From the Display group menu bar, select Tools > Profiles > X Profile. A Horizontal Profile plotwindow appears.

2. From the Display group menu bar, select Tools > Profiles > Y Profile. A Vertical Profile plotwindow appears.

3. Move these two plots to the side of the display group.

4. Click-and-drag the cursor inside the Image window to interactively view the elevation profiles.When you release the mouse button, the position of the red bar in the Horizontal and VerticalProfile windows marks the position of the center of the Zoom window along the profile.


5. Close the two profiles when you are finished.

Arbitrary Elevation TransectENVI Classic also provides a tool for extracting elevation profiles along multiple arbitrary transects.

1. From the Display group menu bar, select Tools > Profiles > Arbitrary Profile (Transect). ASpatial Profile Tool dialog appears.

2. Click inside the Image window to define a segment of the desired transect. Or, hold down the leftmouse button to draw a free-form transect. Right-click to close the last line segment, and right-click again to extract the profile. A Spatial Profile plot window appears.


3. Repeat for each desired profile. Each is assigned a new color and number. You can also drawprofiles in the Scroll or Zoom windows by selecting the appropriate radio button in the SpatialProfile Tool dialog.

4. Click-and-drag inside the Spatial Profile. The Zoom box in the Image window tracks the profile.

5. Zoom to specific ranges in the plot by clicking-and-dragging the middle mouse button to draw abox. Click the middle mouse button outside of the plot axis to reset the original zoom.

6. When you are finished, close the Spatial Profile Tool and any Spatial Profile plot windows.

Density Slice the DEMDensity slicing provides a means of visually enhancing radar differences based on image brightness.


1. From the Display group menu bar, select Tools > Color Mapping > Density Slice. A DensitySlice Band Choice dialog appears.

2. SelectMask under topsar_cor.img and click OK. A Density Slice dialog appears.

3. Click Clear Ranges.

4. From the Density Slice dialog menu bar, select Options > Add New Ranges. An Add DensitySlice Ranges dialog appears.

5. In the Range Start field, enter 0.

6. In the Range End field, enter 700.

7. In the # of Ranges field, enter 10.

8. Click OK, followed by Apply in the Density Slice dialog.

9. Experiment with different colors for each range by clicking Edit Range in the Density Slicedialog.

10. Use image linking and dynamic overlay to compare the density-sliced image with the gray scaleDEM.

11. Close the density-sliced image when you are finished. Leave the gray scale DEM open for thenext exercise.


Overlay Elevation Contours1. From the Display group menu bar, select Overlay > Contour Lines. A Contour Band Choice

dialog appears.

2. SelectMask under topsar_cor.img and click OK. A Contour Plot dialog appears. ClickClear Levels.

3. From the Contour Plot dialog menu bar, select Options > Add New Levels. An Add ContourLevels dialog appears.

4. In the Level Start field, enter 0.

5. In the Level Inc field, enter 50.

6. In the # of Levels field, enter 15. Click OK.

7. Click Apply in the Contour Plot dialog to plot the contours on the DEM image. Examine therelationship between contour lines and image brightness.


8. In the Available Bands List, select the [L-HH] band under ts0218lp.syn and click LoadBand. The contour lines overlay the SAR data.

9. Select File > Cancel from the Contour Plot dialog menu bar to remove the contour lines.

View 3D Perspective and Overlay ImageENVI Classic can generate interactive 3D perspective views from DEM data and also overlay co-registered image data. Your monitor must be able to display 24-bit color. TOPSAR provides the idealdataset for this function because it includes both SAR and DEM data.

1. In the Available Bands List, selectMask under topsar_cor.img and click Load Band.

2. From the ENVI Classic main menu bar, select Topographic > 3D SurfaceView. An AssociatedDEM Input File dialog appears.

3. SelectMask under topsar_cor.img and click OK. A 3D SurfaceView Input Parametersdialog appears.

4. In the DEM min plot value field, enter 0.

5. Set the Vertical Exaggeration field to 20.

6. Select the Full radio button under Image Resolution. Click OK. A 3D SurfaceView dialogappears.

7. From the 3D SurfaceView dialog menu bar, select Options > Surface Controls. A 3DSurfaceView Controls dialog appears, which allows you control the surface display.

8. In the 3D SurfaceView Controls dialog, click the Surface Style drop-down list and selectWireto display the surface as a wire-mesh. The left mouse button controls image rotation, the middlemouse button controls panning, and the right mouse button controls zooming.

9. To see a SAR image from a 3D perspective, replace the DEM image in the current display groupwith a SAR image. Then, repeat Steps 4-9.

See the tutorial "3D SurfaceView and Fly-Through" on page 2 or ENVI Classic Help for more


details on 3D SurfaceView.

Smooth the DEMArtifacts and strange patterns may not be immediately apparent in the original DEM, but they becomeenhanced when creating topographic modeling images such as slope, aspect, and shaded-relief images.You can minimize some of these effects by selecting Enhance > Filter > Smooth orMedian from theDisplay group menu bar associated with a slope, aspect, or shaded-relief image. However, the bestapproach is to smooth the original DEM.

1. From the ENVI Classic main menu bar, select Filter > Convolutions and Morphology. TheConvolutions and Morphology Tool dialog appears.

2. From the Convolutions and Morphology Tools dialog menu bar, select Convolutions > Median.

3. Set the Kernel Size to 7.

4. Click Apply to File. The Convolution Input File dialog appears.

5. SelectMask under topsar_cor.img and click OK. The Convolution Parameters dialogappears.

6. In the Enter Output Filename field, enter medianfilter and click OK.

7. In the Available Bands List, select Conv under medianfilter and click Load Band. Youmay not notice much difference between the smoothed and original DEMs, however this step isnecessary for generating topographic modeling and feature images.


Generate Topographic Modeling ImagesENVI Classic provides tools for processing DEMs to extract parametric information (including slope andaspect) and for generating Lambertian (shaded-relief) surfaces. ENVI Classic fits a plane to a 3 x 3kernel centered over each pixel and calculates the slope and aspect of the plane. The slope is measuredin degrees, from 0 to 90. Aspect angle is measured with 0 degrees to the north with increasing angles ina clockwise direction. A root mean square (RMS) error image is also generated that indicates theplanarity of the 9-pixel kernel.

1. From the ENVI Classic main menu bar, select Topographic > Topographic Modeling. A TopoModel Input DEM dialog appears.

2. Select Conv under medianfilter and click OK. A Topo Model Parameters dialog appears.

3. Under Select Topographic Measures to Compute, use the Ctrl key to select only Slope(Degrees)Slope, Slope (Percent), Aspect, Shaded Relief, and RMS Error.

4. Click the Compute Sun Elevation and Azimuth button.

5. Set the Date for Calculation to Nov 11 1996.

6. Set the GMT Time to 12:00:00.

7. In the Lat field, enter –37 degrees, 21 minutes, 0 seconds. In the Lon field, enter 145 degrees, 17minutes, 0 seconds. Click OK to return to the Topo Model Parameters dialog.

8. In the X/Y Pixel Size (Meters) fields, enter 10.

9. In the Enter Output Filename field, enter ts_model.img. Click OK to generate the images.

10. In the Available Bands List, select the Slope, Aspect, Shaded Relief, and RMS Error images(one-by-one), and click Load Band.

11. Use image linking and dynamic overlays to compare them to the original DEM image. The


following figure shows a portion of the aspect image:

Generate Topographic Feature ImageYou can create a classification output image that classifies each pixel into one of the following terraintypes or morphometric features: peak, ridge, pass, plane, channel, or pit. The slope and curvature of thesurface determines the morphometric feature. For example, a sloping surface that is concave in thecross-sectional direction is a channel. A sloping surface that is convex in the cross-sectional direction isa ridge. Peaks have a convex cross-section and convex longitudinal curvature, while pits have concavecurvatures. Passes have one convex curvature and one concave curvature.

1. From the ENVI Classic main menu bar, select Topographic > Topographic Features. TheTopographic Feature Input DEM dialog appears. A smoothed DEM is required for this function.

2. Select Conv under medianfilter and click OK. The Topographic Feature Parameters dialogappears.

3. Set the Topographic Kernel Size to 7.

4. In the X/Y Pixel Size (Meters) fields, enter 10.


5. The slope (in degrees) and curvature tolerance values are used to determine when a pixel isclassified as a peak, pit, or pass, versus a channel or ridge. For a pixel to be classified as a peak,pit, or pass, the slope value must be less than the slope tolerance and the cross-sectional curvaturemust be greater than the curvature tolerance. Increasing the slope tolerance and decreasing thecurvature tolerance increases the number of peaks, pits, and passes in the classified output. Forthis exercise, accept the default values.

6. In the Enter Output Filename field, enter topofeature and click OK.

7. In the Available Bands List, select the band named Topographic Features and click Load Band.The feature image is actually a classification image, which is color-coded according to differenttopographic features.

8. From the Display group menu bar, select Overlay > Annotation. The Annotation dialog appears.

9. From the Annotation dialog menu bar, select Object > Map Key.

10. Click the Color box and select Black. Click the Background box and selectWhite.

11. Click once in the image to show the map key. Move it to a preferred location by dragging the reddiamond handle. Right-click to lock the map key in place.


12. Compare the feature image classification to the DEM and to the topographic modeling images.

13. Experiment with different values in the Slope Tolerance and Curvature Tolerance fields of theTopographic Feature Parameters dialog, then regenerate the topographic feature images.

14. When you are finished, select File > Exit from the ENVI Classic main menu bar.

Copyright Notice:

ENVI Classic is a registered trademark of Exelis Inc.

QUAC and FLAASH are registered trademarks of Spectral Sciences, Inc.


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