90m SRTM DEM
I am working on a project in Belize and the best DEM data I could find was 90m SRTM data. The data is in meters which is what I expected but there are erroneous elevations. I want to keep all elevation data lower 1,133m and make all erroneous data above 1,133m into NoData.
I have tried smoothing but smoothing does not work well with small clumps of 65,000m areas. Basically, to get the erroneous elevation figures down to manageable level using smoothing, the DEM will be worthless. I have tried hawth's tool but it did not want to cooperate with 9.3.1. Please help so I can stop beating my head against a brick wall.
Mapping Center Answer:
You need to use the Set Null tool in Spatial Analyst extension. The expression to use will be "Value >= 1133". In the output raster, all cells that meet the criteria in your expression will be set to NoData -- all other cells will retai thier original input vlaues.
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