Confusion about Visibility SPOT value in ArcGIS Pro
I'm trying to perform an analysis using the Visibility tool, 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-f...) 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.
What I find confusing is that on the ArcGIS Pro website, it provides this figure which shows the SPOT extending up to a 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?
