1

I'm in the process of performing a visibility analysis using the Visibility tool in ArcGIS Pro 3.0, but something is confusing me about the SPOT parameter. On the ArcGIS Pro website (https://pro.arcgis.com/en/pro-app/2.8/tool-reference/3d-analyst/using-viewshed-and-observer-points-for-visibility.htm) it says that the SPOT is "used to define the surface elevations for the observation points". If I'm using a DEM for my elevation surface, I would assume the SPOT would be the DEM value at my observer point. This fits with the description in this video (https://www.youtube.com/watch?v=q6i9yVm5lsI&t=108s&ab_channel=GIS-Toolstounderstandtheworld) which uses the diagram below. You can see that the SPOT is the height of the terrain under the observer point.

enter image description here

What I find confusing is that on the ArcGIS Pro website, it provides the figure below which shows the SPOT extending up to a horizontal plane above the observer point. Shouldn't the SPOT value be the height of that brown hill that the observer is standing on, or am I misunderstanding something?

enter image description here

1 Answer 1

1

I think it's a poor illustration, but the Esri figure actually seems to be showing the same as the NTNU figure, notice the SPOT line intersects with a dashed line that looks like it would intersect the horizon plane

enter image description here

2
  • 1
    Yea I think you're right, the line you highlighted green is probably the SPOT elevation, it's just drawn in a very confusing way
    – Morgan
    Commented Oct 9, 2022 at 21:21
  • Yes, very confusing. The NNTU one is so much clearer.
    – user2856
    Commented Oct 10, 2022 at 0:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.