topic Re: Estimating Elevation in ArcGIS Pro in ArcGIS Pro Questions

Estimating Elevation in ArcGIS Pro

rullasaad — Sun, 05 Sep 2021 17:43:52 GMT

Hello everyone,

I need help determining elevation for some points in ArcGIS pro. The case is as follow:

1- I have a set of 200k points that includes x,y,z data for each.

2- Now, I have an additional "four points" with known x and y only, I need to estimate the elevations of these four new points using the previous 200k points (I have created a separate shapefile for these four points).

I have tried many tools (interpolation, calculate z, etc.) but it all did not work and gives a null geometry.

Any thoughts on how can I do this?

Thanks a lot in advance.

Re: Estimating Elevation in ArcGIS Pro

David_Brooks — Sun, 05 Sep 2021 18:25:03 GMT

@rullasaad you can convert the points to a raster surface and then interpolate the values for the points from that

Re: Estimating Elevation in ArcGIS Pro

rullasaad — Sun, 05 Sep 2021 18:29:51 GMT

Will I be able to know the elevation of the four points exactly in this case?

And which points shall I convert to a raster, the 200k or the four points or both of them together?

Thanks a lot David.

Re: Estimating Elevation in ArcGIS Pro

David_Brooks — Sun, 05 Sep 2021 18:49:42 GMT

@rullasaad so in this scenario, I've assumed that you have a relatively even distribution of points from which to create a terrain surface, and that your 4 points are somewhere within the main cluster of 200k?

Re: Estimating Elevation in ArcGIS Pro

rullasaad — Sun, 05 Sep 2021 19:12:22 GMT

Well, I have manually added the four points using "absolute X,Y" but did not add them to the 200k points. And yes the 200k points are almost evenly distributed, the site is a landfill.

Re: Estimating Elevation in ArcGIS Pro

DanPatterson — Sun, 05 Sep 2021 19:17:38 GMT

Interpolate a raster surface using your larger point set. (pay attention to cell size and other raster parameters.

Then with your smaller 4 point featureclass use

Extract Values to Points (Spatial Analyst)—ArcGIS Pro | Documentation

I assume that you have the Spatial Analyst Extension

Re: Estimating Elevation in ArcGIS Pro

David_Brooks — Sun, 05 Sep 2021 19:23:33 GMT

One way to do it:

1. Interpolate a surface model (raster terrain) using IDW

https://pro.arcgis.com/en/pro-app/latest/tool-reference/spatial-analyst/idw.htm

With your 200k point dataset as the input

2. Then run Extract Values to Points: https://pro.arcgis.com/en/pro-app/latest/tool-reference/spatial-analyst/extract-values-to-points.htm

...with your 4 point dataset as the input and your new raster as the surface, with interpolation checked.

With regard to step 1, there are many different interpolation methods for generating a raster surface,

https://pro.arcgis.com/en/pro-app/latest/tool-reference/3d-analyst/comparing-interpolation-methods.htm

And in your instance, Topo to Raster might be a better tool (if you need to preserve ridges and drainage channels). But IDW is good enough for what you need.

Re: Estimating Elevation in ArcGIS Pro

PrimaliWeerasinghe1 — Tue, 07 Sep 2021 00:30:41 GMT

with your elevation data, create DEM with suitable cell size and then find
the elevation for those unknown 04 points.