topic Aspect formula in ArcGIS Spatial Analyst Questions https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400663#M5642 <HTML><HEAD></HEAD><BODY><SPAN>Hi all,</SPAN><BR /><BR /><SPAN>Here is a question. The help files on ArcGIS gives the calculation of aspect for a DEM as aspect = 57.29578 * atan2 ([dz/dy], -[dz/dx])</SPAN><BR /><BR /><SPAN>This is perhaps a pretty basic question which I'm not able to get around- what is 57.29578? Is it a correction factor? I'm assuming its an angle b/w 0-360 but I want to know why this particular decimal number is being used.</SPAN><BR /><BR /><SPAN>Any tips on the above would be great.</SPAN><BR /><BR /><SPAN>Thanks,</SPAN><BR /><SPAN>Raghu</SPAN></BODY></HTML> Wed, 14 Sep 2011 19:15:49 GMT raghuramnarasimhan 2011-09-14T19:15:49Z Aspect formula https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400663#M5642 <HTML><HEAD></HEAD><BODY><SPAN>Hi all,</SPAN><BR /><BR /><SPAN>Here is a question. The help files on ArcGIS gives the calculation of aspect for a DEM as aspect = 57.29578 * atan2 ([dz/dy], -[dz/dx])</SPAN><BR /><BR /><SPAN>This is perhaps a pretty basic question which I'm not able to get around- what is 57.29578? Is it a correction factor? I'm assuming its an angle b/w 0-360 but I want to know why this particular decimal number is being used.</SPAN><BR /><BR /><SPAN>Any tips on the above would be great.</SPAN><BR /><BR /><SPAN>Thanks,</SPAN><BR /><SPAN>Raghu</SPAN></BODY></HTML> Wed, 14 Sep 2011 19:15:49 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400663#M5642 raghuramnarasimhan 2011-09-14T19:15:49Z Re: Aspect formula https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400664#M5643 <HTML><HEAD></HEAD><BODY><SPAN>Its converting the output from atan2, which is radians, to degrees.</SPAN><BR /><SPAN>1 radian = 57.29578 degrees.</SPAN></BODY></HTML> Wed, 14 Sep 2011 20:38:54 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400664#M5643 Anonymous User 2011-09-14T20:38:54Z Re: Aspect formula https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400665#M5644 <HTML><HEAD></HEAD><BODY><SPAN>Great, thanks Sean.</SPAN></BODY></HTML> Wed, 14 Sep 2011 20:45:31 GMT https://community.esri.com/t5/arcgis-spatial-analyst-questions/aspect-formula/m-p/400665#M5644 raghuramnarasimhan 2011-09-14T20:45:31Z