The GRASS programs i.target and i.points3 must be run prior to i.rectify3.
The first prompt in the program asks the user for the name of the group containing the raster map layers to be rectified.
Enter imagery group to be rectified Enter 'list' for a list of existing imagery groups Enter 'list -f' for a verbose listing Hit RETURN to cancel request >The user is then asked to select the map layer(s) within the group to be rectified:
Please select the file(s) to rectify by naming an output file center, tab(:); l l. spot.1 in demo:......... spot.2 in demo:......... spot.3 in demo:......... spotclass in demo:spotrectify.. spotreject in demo:......... (Enter list by any name to get a list of existing raster files) AFTER COMPLETING ALL ANSWERS, HITMore than one raster map layer may be rectified at a time. Each raster map layer should have a unique output file name.TO CONTINUE (OR TO CANCEL)
Next the user is asked to select one of two geographic region settings:
center, tab(:); l s l l. Please select one of the following options 1.:Use the current region in the target location 2.:Determine the smallest region which covers the imagei.rectify3 will only rectify that portion of the image that occurs within the chosen geographic region setting. Only that portion will be relocated in the target data base. It is therefore important to check the current geographic region settings in the target location if choice number one is selected.
The rectified (raster) image will be located in the target LOCATION when the program is completed. The original unrectified raster map layers are not modified or removed.
Michael Shapiro, U. S. Army Construction Engineering Research Laboratory wrote the original i.rectify program, from which the new program was developed.