topic Re: Wrong slope values when converting raster bathymetry data to slope in ArcGIS Spatial Analyst Questions https://community.esri.com/t5/arcgis-spatial-analyst-questions/wrong-slope-values-when-converting-raster/m-p/274856#M3907 <HTML><HEAD></HEAD><BODY><SPAN>Hi,</SPAN><BR /><BR /><SPAN>You have your X Y units were in decimal degrees and Z units in meters/feet. In this case, you will either have to use appropriate </SPAN><A href="http://resources.arcgis.com/en/help/main/10.1/index.html#//009z000000vm000000">Z-factor</A><SPAN> for particular latitudes or </SPAN><A href="http://resources.arcgis.com/en/help/main/10.1/index.html#//00170000007q000000">Re-project</A><SPAN> the input raster to a projected coordinate system and run slope again.</SPAN><BR /><BR /><SPAN>Hope this helps!</SPAN><BR /><BR /><SPAN>Regards,</SPAN><BR /><SPAN>Prasanta.</SPAN></BODY></HTML> Thu, 21 Mar 2013 21:54:50 GMT PrasantaBhattarai 2013-03-21T21:54:50Z Wrong slope values when converting raster bathymetry data to slope https://community.esri.com/t5/arcgis-spatial-analyst-questions/wrong-slope-values-when-converting-raster/m-p/274855#M3906 <HTML><HEAD></HEAD><BODY><SPAN>Hi</SPAN><BR /><BR /><SPAN>It seems this topic has been covered a fair bit in this forum but I haven't found anything that has helped yet. I have 30 sec and 1 minraster layers of bathymetry from GEBCO 08 Grid data that I'm trying to convert to slope layers. I've imported the raster bathymetry layer into ArcMap and with a spatial reference of GCS_WGS_1984 (Angular unit degree, Datum D_WGS_1984). I've tried to calculate the slope for the area but all my values are unrealistic i.e. most values are around 89 degrees or up to 2000% when calculated as a percent. I think this has something to do with the z value but I'm not sure what&nbsp; else to do. I've tried defining the z units for the grid as in this article,&nbsp; </SPAN><A href="http://support.esri.com/es/knowledgebase/techarticles/detail/30566">http://support.esri.com/es/knowledgebase/techarticles/detail/30566</A><SPAN>&nbsp; ...with no luck. </SPAN><BR /><BR /><SPAN>Does this have something to do with the fact the raster layer has the GCS_WGS_1984 spatial reference? I understand the x,y and z units must be the same but I'm not sure what to change to do this.</SPAN><BR /><BR /><SPAN>Thanks!</SPAN></BODY></HTML> Thu, 21 Mar 2013 17:22:10 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/wrong-slope-values-when-converting-raster/m-p/274855#M3906 KylaGraham 2013-03-21T17:22:10Z Re: Wrong slope values when converting raster bathymetry data to slope https://community.esri.com/t5/arcgis-spatial-analyst-questions/wrong-slope-values-when-converting-raster/m-p/274856#M3907 <HTML><HEAD></HEAD><BODY><SPAN>Hi,</SPAN><BR /><BR /><SPAN>You have your X Y units were in decimal degrees and Z units in meters/feet. In this case, you will either have to use appropriate </SPAN><A href="http://resources.arcgis.com/en/help/main/10.1/index.html#//009z000000vm000000">Z-factor</A><SPAN> for particular latitudes or </SPAN><A href="http://resources.arcgis.com/en/help/main/10.1/index.html#//00170000007q000000">Re-project</A><SPAN> the input raster to a projected coordinate system and run slope again.</SPAN><BR /><BR /><SPAN>Hope this helps!</SPAN><BR /><BR /><SPAN>Regards,</SPAN><BR /><SPAN>Prasanta.</SPAN></BODY></HTML> Thu, 21 Mar 2013 21:54:50 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/wrong-slope-values-when-converting-raster/m-p/274856#M3907 PrasantaBhattarai 2013-03-21T21:54:50Z