README notes for radarsat1_20080615_v2.zip shapefile June 17, 2008 (based on original distribution e-mail) I'm attaching the most comprehensive RADARSAT derived flood extent shapefile we have to date. Open the .LYR file to display correct colors and legend. (GRIDCODE 1 = Probable Water; GRIDCODE 2 = Probable Flood Water). It covers all of southern Wisconsin except a strip along Lake Michigan. NOTE: This Copyright inscription should be displayed on all RADARSAT-1 image products: "(C) Canadian Space Agency/Agence spatiale canadienne (2008)" These are the processing notes from Dr. Chipman at Dartmouth on the attached RADARSAT-1 derived product: These should be viewed as tentative only; I did this in a hurry and can refine it another time. In particular, I haven't attempted to identify areas where there's flooding underneath a forest canopy (that's possible, but more complicated). Because of the problem with slopes in the Driftless area, the processing was slightly more complicated than before: (1) Adjusted coordinates to fit more closely with 1:24k maps. (2) Reprojected from UTM zone 15 to WTM83. (3) Subset Wisconsin area. (4) Ran an "enhanced Frost filter" (5x5 kernel) to reduce impact of speckle noise. (5) Classified pixels with values in the range of 1-35 as water. *** Note: slight change from last time *** (6) Distinguished flooding from "normal" water pixels (lakes, etc.) using WISCLAND. (6a) Eliminated any "flooding" on steep slopes (actually radar shadows). *** Note: new step added *** (7) Discarded any "clumps" smaller than 5 pixels. (8) Exported to GeoTIFF (blue (1) = normal water, red (2) = potential flooding). (9) Exported to shapefile and layer file. This covers nearly all of southern Wisconsin from the Mississippi most of the way over to Lake Michigan, but misses a small strip along the eastern edge of the state. Early feedback from USDA WI-FSA indicates that there is a 10-15% underestimation of flood waters so be cautious in using this data for anything more than guidance on location of probable flooding. -- Sam Dr. Sam Batzli, WisconsinView Director Environmental Remote Sensing Space Science & Engineering Center 1225 W Dayton St, FL 12 University of Wisconsin-Madison Madison, WI 53706 608-263-3126 (office)