Software & services for georeferencing of natural history collections data
Georeferencing ASTER Data
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ENVI User's Guide: Map Tools Georeferencing ASTER Data Use Georeference ASTER to build geometry files and to georeference ASTER data based on header information. ENVI performs a precision geocoding of the ASTER data using the latitude and longitude information contained in the HDF file. Building ASTER Geometry Files Use Build Geometry File to build an ASTER geometry file to calculate the X and Y coordinates for each pixel. You may select the desired projection for the coordinates. You can georeference the ASTER data by using the results from this procedure as the IGM input file in the Georeferencing from Input Geometry function. Note The capability to georeference is only available for ASTER level 1A data. ASTER level 1B HDF files already contain georeferenced data and are typically in UTM projection with a rotation. To convert ASTER Lev el 1B to north-u p UTM or other pr ojection s (i.e., without r otation), select Map Convert Map Projection from the ENVI main menu bar. See Converting Map Projections for detailed instructions. You can also achieve the conversion using orthorectification; see Orthorectification for details. Open an ASTER file with the File Open External File EOS ASTER option from the ENVI main menu bar. 1. Select one of the following menu options: 2. Basic Tools Preprocessing Data-Specific Utilities ASTER Build Geometry File Map Georeference ASTER Build Geometry File Spectral Preprocessing Data-Specific Utilities ASTER Build Geometry File When the file selection dialog appears, select the ASTER image file. The Build IGM for ASTER Data dialog appears. 3. Select the desired map projection for the X,Y coordinates by clicking on a projection type in the list. 4. Select whether to output the result to file or memory by clicking the File or Memory button. If the output is to a file, enter or choose an output filename. 5. Click OK. 6. ENVI extracts the needed information from the ASTER header file and places the output coordinate bands in the Available Bands List. Georeferencing ASTER Data Use Georeference Data to georeference ASTER data based on header information. ENVI performs a precision geocoding of the ASTER image using a complete geometry model of the eart h and satellite orbit. Georeferencing ASTER Data http://geol.hu/data/online help/Georeferencing ASTER Data.html 1 of 2 10/3/2011 10:54 PM
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ENVI User's Guide: Map Tools
Georeferencing ASTER Data
Use Georeference ASTER to build geometry files and to georeference ASTER data based on header information. ENVI performs a precision geocoding of the ASTERdata using the latitude and longitude information contained in the HDF file.
Building ASTER Geometry Files
Use Build Geometry File to build an ASTER geometry file to calculate the X and Y coordinates for each pixel. You may select the desired projection for the coordinates.
You can georeference the ASTER data by using the results from this procedure as the IGM input file in the Georeferencing from Input Geometry function.
Note
The capability to georeference is only available for ASTER level 1A data. ASTER level 1B HDF files already contain georeferenced data and are typically in UTM
projection with a rotation. To convert ASTER Level 1B to north-up UTM or other projections (i.e., without rotation), select Map Convert Map Projection from
the ENVI main menu bar. See Converting Map Projections for detailed instructions.
You can also achieve the conversion using orthorectification; see Orthorectification for details.
Open an ASTER file with the File Open External File EOS ASTER option from the ENVI main menu bar.1.
Select one of the following menu options:2.
Basic Tools Preprocessing Data-Specific Utilities ASTER Build Geometry File
Map Georeference ASTER Build Geometry File
Spectral Preprocessing Data-Specific Utilities ASTER Build Geometry File
When the file selection dialog appears, select the ASTER image file. The Build IGM for ASTER Data dialog appears.3.
Select the desired map projection for the X,Y coordinates by clicking on a projection type in the list.4.
Select whether to output the result to file or memory by clicking the File or Memory button. If the output is to a file, enter or choose an output filename.5.
Click OK.6.
ENVI extracts the needed information from the ASTER header file and places the output coordinate bands in the Available Bands List.
Georeferencing ASTER Data
Use Georeference Data to georeference ASTER data based on header information. ENVI performs a precision geocoding of the ASTER image using a complete
geometry model of the earth and satellite orbit.
Georeferencing ASTER Data http://geol.hu/data/online_help/Georeferencing_ASTER_Data.html
1 of 2 10/3/2011 10:54 PM
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Open an ASTER file with the File Open External File EOS ASTER option from the ENVI main menu bar.1.
Select one of the following options:2.
Basic Tools Preprocessing Data-Specific Utilities ASTER Georeference Data
Map Georeference ASTER Georeference Data
Spectral Preprocessing Data-Specific Utilities ASTER Georeference Data
When the file selection dialog appears, select the ASTER image file. The Georeference ASTER Data dialog appears.3.
Select the desired output map projection by clicking on a projection type in the list. By default, a UTM map projection is selected based on header information.4.
Enter the Number of Warp Points to use. You may select a number of warp points up to the number of samples and lines in your image. If you select fewer warp
points, they will be evenly spaced throughout the image.
5.
NoteUsing a large number of warp points will increase the processing time considerably.
If desired, specify to save the warp points to a GCP file, by entering or choosing an output filename.6.
Click OK.7.
When the standard Registration Parameters dialog appears, select the warping and resampling methods and change the output dimensions, if desired (see
Warping and Resampling for details). The triangulation method is recommended to produce the most accurate results; however, that method is much slower than
polynomial warping.
8.
Enter or choose an output filename and click OK.9.
ENVI Online Help (August 12, 2005)
Georeferencing ASTER Data http://geol.hu/data/online_help/Georeferencing_ASTER_Data.html
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