topic Show Slope and Direction in ArcGIS Spatial Analyst Questions

Show Slope and Direction

BrianBulla — Fri, 12 Mar 2021 20:25:29 GMT

Hi,

Pretty much a noob to processing raster, but I've managed to take some LIDAR data and create a DEM. From the DEM, I've created a slope raster. Symbolizing it as a vector to see all the arrows, I was hoping it would show me the direction of the slope, but all the arrows are just pointing the same direction.

Any guidance on how to properly process my DEM so I can see both slope and direction in the same raster so all the arrows point in the proper direction??

Re: Show Slope and Direction

DanPatterson — Fri, 12 Mar 2021 20:32:24 GMT

Your coordinates wouldn't be in decimal degrees would they?

Make sure that your coordinates, X, Y and Z are in the same units... eg meters

Also, Aspect Aspect (Spatial Analyst)—ArcGIS Pro | Documentation

is the term for the direction that a slope points.

There is a sort of combo function that incorporates slope and aspect

Aspect-Slope function—ArcGIS Pro | Documentation

lots of options once you can confirm the coordinate

Re: Show Slope and Direction

BrianBulla — Fri, 12 Mar 2021 20:39:17 GMT

Hi Dan. Actually I saw that article on the Aspect-Slope Function. Where do I find these .RFT files??

Hmmmm....my coordinate system says 'Undefined', but my source lidar data is in UTM meters. I guess I have to manually set the coordinate system for each product derived from the LAS dataset??

Re: Show Slope and Direction

JayantaPoddar — Fri, 12 Mar 2021 21:58:50 GMT

You could use Aspect, as suggested by Dan to get the direction raster of the downhill slope.

Then use Extract Values to Points to transfer the cell values of Aspect Raster to the Point Feature class.

From symbology of the Point Feature, you may then rotate the symbol based on Aspect Attribute.

In my above example, I have also extracted the values of Slope Raster to the same Point features, and quantitatively classified (Graduated Color) based on Slope values.

Re: Show Slope and Direction

BrianBulla — Tue, 16 Mar 2021 13:12:51 GMT

Nice....thanks!! Things are looking much better now.