# Estimating Elevation in ArcGIS Pro

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09-05-2021 10:43 AM
New Contributor

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?

7 Replies
Regular Contributor

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

David
..Maps with no limits..
New Contributor

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.

Regular Contributor

@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?

David
..Maps with no limits..
New Contributor

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.

MVP Esteemed Contributor

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

... sort of retired...
Regular Contributor

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.h...

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.

David
..Maps with no limits..
New Contributor II
with your elevation data, create DEM with suitable cell size and then find
the elevation for those unknown 04 points.