topic Re: Point aspect from TIN in 3D Questions

Point aspect from TIN

CamillaRootes — Fri, 15 Aug 2014 14:11:48 GMT

Hi,

I have a shapefile containing a series of points and would like to know the surface aspect at these locations. I have a TIN DEM and I want to extract aspect values from the TIN into the points' attribute table. I know that this is possible for raster DEMs (https://community.esri.com/message/37161?sr=search&searchId=2a454f81-4783-4cf7-948d-0924398ee4b4&searchIndex=3#37161) but I haven't been able to find a way to extract this information from a TIN

Can anyone advise me on how to get the TIN aspect at my points? I am using Arc 10.1 with the basic license.

Thanks

Re: Point aspect from TIN

RiyasDeen — Fri, 15 Aug 2014 14:33:36 GMT

You will need 3D analyst licence for this.

Use Surface Aspect tool to create polygon FC with Aspect values ArcGIS Help 10.1‌
Use Intersect tool to intersect your point features with Aspect polygon.
Export as table using Table to Table tool

Re: Point aspect from TIN

CamillaRootes — Mon, 18 Aug 2014 09:05:33 GMT

I do have a 3D analyst license and have given this method a go - it seems to work just fine. Thanks for your help!

Re: Point aspect from TIN

CamillaRootes — Mon, 18 Aug 2014 10:50:45 GMT

One thing I have noticed using this technique is that it only works with the Aspect code. Creating the TIN surface aspect layer converst the TIN triangles' aspect values into aspect code. Using the intersect tool then assigns an aspect code to each of my sample points.

It would be better to have the raw aspect value for the sample points. Do you know a way of getting the 'raw' aspect value rather than the aspect code?

Re: Point aspect from TIN

RiyasDeen — Mon, 18 Aug 2014 12:27:08 GMT

On thing that quickly pops up is, you can create a Class Breaks Table for every degree value containing 360 rows or every half degree containing 720 rows, depending on your accuracy requirement.

will post back if I can think of something else.

Re: Point aspect from TIN

CamillaRootes — Mon, 18 Aug 2014 13:51:40 GMT

Yes I'd been considering that, was just wondering if there was a more elegant solution! But I can always use the class breaks idea if we can't think of anything else.