deepgis Posted July 22, 2011 Report Share Posted July 22, 2011 Can someone help me regarding ndvi values. I want to detect change in vegetative cover in two different images of the same area. Both images are of the same month but of different years. First image related to dry year whereas second image related to good rainfall year. How I can compare the both images and detect the change. Quote Link to comment Share on other sites More sharing options...
rahmansunbeam Posted July 22, 2011 Report Share Posted July 22, 2011 Easiest way to do that is to use ENVI. You'll find Vegetation Delineation tool under SPEAR tool. Quote Link to comment Share on other sites More sharing options...
3dbu Posted July 22, 2011 Report Share Posted July 22, 2011 check this tutorials http://www.oeidrus-portal.gob.mx/oeidrus_qro/PUBLICACIONES/ESTUDIOS/NDVIQRO_ACTUAL.HTM is in spanih but have the methods for make change land analyst using NDVI ...if have proble i can give to you support... regards Quote Link to comment Share on other sites More sharing options...
pasfans01 Posted July 23, 2011 Report Share Posted July 23, 2011 based on my experience, NDVI value is scene dependent, so it highly affected by the vegetation reflectance itself, angle of incoming irradiance, and atmosphere condition, so when you compared two images from different year, the value range of dense vegetation probably different, you can do LUT color mapping in ENVI and visual interpretation to aid the classification process, to compare the difference, you can use change detection tool from ENVI in menu Basic Tools>Change Detection>Compute Difference map, you can also calculate the differences statistics from that tool Quote Link to comment Share on other sites More sharing options...
deepgis Posted July 25, 2011 Author Report Share Posted July 25, 2011 Respected rahmansunbeam, 3dbu and Pasfanso1 thank you very much for valuable suggestions. Quote Link to comment Share on other sites More sharing options...
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