FAQ

Sponsor Frequently Asked HyMap Questions

Q: The ATREM vapor files don't have georeferencing info - I have to copy it from the corresponding geo file. Can this be done at your end on the remaining CDs?

A: The ATREM files are not geometrically corrected., therefore, copying the georeferencing information from the _geo file is not a viable option. All of the data files with the exception of the _geo file are in input space (sample, line). They can be converted to georeferenced space using "Utilities > Data
Specific Utilities > Hymap > HyMap Geocorrect from GLT Lookup File", but you really should do all your processing in the input space and convert the results to georeferenced space after processing. Due to scientific and processing consideration and size constraints of warping image cubes the only file provided in georeferenced space is the _geo file.

If you are just after the map location of some pixels in input space (ie. your water vapor image or reflectance cube) you can open the _igm file,
display both the X and Y bands then link all three images together. Using the cursor location value you get the X&Y map location and pixel value of the third image.

Q: My UNIX machine doesn't like the filenames on the CD - I have to read them on a PC then FTP to UNIX. On my CD writer, there was a flag that could be set to write in a format that's cross-platform compatible. Can you do this on the remaining CDs?

A: The default format for HyMap CDs is "Joliet", which is a PC format. We can provide data to UNIX users on 8mm tape on request. If you absolutely can not work with the CDs we send you and have to have the data on CD, please contact AIG directly to make alternate arrangements.

Q: Could you tell me what datum you used for the georef files (I am currently assuming WGS84)?

A: Though we required WGS84 for the aircraft navigation, the default output projection/datum for ENVI (that most commonly used on US maps) is UTM/NAD27 and that is what we used. the projection information is in the ENVI header of the _geo file. Once you've produced results and made the correction to the flightline data using the _glt file and the provided geocorrection function, the projection can be easily converted.

For Additional Help or Information about the HyMap Groupshoot data contact:
Analytical Imaging and Geophysics LLC
4450 Arapahoe Ave., Suite 100
Boulder, CO 80303 USA
Phone: 303-604-2844 , FAX: 303-665-6090
WWW: http://www.aigllc.com E-Mail: services@aigllc.com