Does your SPOT image come with an ancillary file with a .dim extension? If so, then open your file as SPOT DIMAP format using File ->Open External File ->SPOT-> DIMAP. This will automatically assign the appropriate wavelengths to the bands. Otherwise, ENVI will open the file as generic TIFF. Next, you can check if ENVI sees the map projection by looking in the Available Bands List to see if the file has a little Globe icon with a '+' symbol next to it that says 'Map Info'. If you click on the +, it should show you the map projection. What does it say for a map projection? Does it show it is in UTM projection? If so, then ENVI sees the map projection fine. This map information should be passed on with the file through any processing and you can confirm this by looking at the Map Info in the Available Bands List. If you are running ArcGIS 9.3 or 10, you do not need to export the file to TIFF to open the file in Arc. Arc will automatically recognize an ENVI format file with a .dat or .img extension so you can open it directly in Arc and the Map Information should be passed along with the file.

Thank you. I found SPOT as DIMAP format. When I load it and roll Map Info, I see the right projection. I stil have problem with ArcGIS 9.3. If I make for example NDVI from me image, it has stil the right projection. But if I use automatic opening in ArcGIS, the image doesnt fit in my shapefile of districts. The districts looks smaller than the image of NDVI, but they should be overlaped. I try load my shapefile to ENVI, but it isnt in the right place (they dont overlap).

I resolved the problem with vector in ENVI. Now the districts and the NDVI image are overlaped . But stil I have the problem with ArcGIS. I dont understand it. Can anybody help with QUAC correction (in my first question)? Thanx :-)

If you opened the file as SPOT DIMAP, do the bands have wavelengths shown in the Available Bands List? Wavelengths should be automatically assigned and you should see the wavelength next to the band name. For example, XS1 (550.00) XS2 (655.00) XS3 (830.00) SWIR (1635) If they are not, you will need to define them in the header file. Go to FIle ->Edit ENVI Header and select your SPOT file. Then go to Edit Attributes ->Wavelengths. Add in the wavelength values for your SPOT data. FWHM values are not required if you do not have them. ENVI will estimate FWHM from the wavelengths and a gaussian distribution.