topic Map Algebra in Elevation Data Questions https://community.esri.com/t5/elevation-data-questions/map-algebra/m-p/766941#M31 <HTML><HEAD></HEAD><BODY><P>Hello my friendly GeoNet community!&nbsp; I need to create a Canopy Height Model. I have a "DSM" that includes man-made structures. and a DEM. I digitized the structures, turned them into a raster and used a Con in Raster Calculator to create a raster layer of just the DEM values, and then mosaiced the DSM into the structures raster layer. So, hypothetically I would has a DSM with no man-made structures. I then used Raster Calculator to Subtract the DEM from the DSM (DSM - DEM) to get a CHM. the result has a bunch of values from -23 to 0... the DSM and the DEM are both 3 ft resolution from the same lidar flight. Does anyone have any ideas what may have gone wrong, or what I can do to fix it?&nbsp;</P><P></P><P>Thank you!!&nbsp;</P></BODY></HTML> Fri, 08 Jun 2018 22:27:34 GMT FaithWebster 2018-06-08T22:27:34Z Map Algebra https://community.esri.com/t5/elevation-data-questions/map-algebra/m-p/766941#M31 <HTML><HEAD></HEAD><BODY><P>Hello my friendly GeoNet community!&nbsp; I need to create a Canopy Height Model. I have a "DSM" that includes man-made structures. and a DEM. I digitized the structures, turned them into a raster and used a Con in Raster Calculator to create a raster layer of just the DEM values, and then mosaiced the DSM into the structures raster layer. So, hypothetically I would has a DSM with no man-made structures. I then used Raster Calculator to Subtract the DEM from the DSM (DSM - DEM) to get a CHM. the result has a bunch of values from -23 to 0... the DSM and the DEM are both 3 ft resolution from the same lidar flight. Does anyone have any ideas what may have gone wrong, or what I can do to fix it?&nbsp;</P><P></P><P>Thank you!!&nbsp;</P></BODY></HTML> Fri, 08 Jun 2018 22:27:34 GMT https://community.esri.com/t5/elevation-data-questions/map-algebra/m-p/766941#M31 FaithWebster 2018-06-08T22:27:34Z