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I am working on an environmental assessment. A data request has been made which it seems is kind of like a reverse viewshed, in that they want a layer that displays all locations within the raster that can view a single high point.

I have the appropriate raster and point layers, but if I run the Viewshed tool as is, pretty much the entire output is returned as not visible. Any thoughts on a workflow to try to capture what they are looking for? The only thing I've come up with so far is to use a bunch of random points surrounding the high point within the raster and include them in a viewshed, but this would not be a complete analysis of the area.

In this scenario, every cell in the raster would be a potential observer. I'll need the output to display values for those cells that can view the high point (1) versus those cells that cannot (0).

I tried running the standard viewshed tool, using the high point as the observer, along with the hillshade as the raster. The output returned the entire area as (0) with only a few cells directly around the high point as (1).

closed as off-topic by PolyGeo Jul 15 '17 at 6:40

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This problem cannot or can no longer be reproduced. Changes to the system or to the asker's circumstances may have rendered the question obsolete, or the question does not include a procedure to enable potential answerers to reproduce the same symptoms. Such questions are off-topic as they are unlikely to help future readers, but editing them to include more details can lead to re-opening." – PolyGeo
If this question can be reworded to fit the rules in the help center, please edit the question.

  • You are correct in using the viewshed tool. You mention both a single high point and then an area. Which do you need? The viewshed and viewshed tools will take multiple points (or lines) as inputs. If you have an area on top of the hill to consider then there are several ways to create those data. The hillshade tools will take lines and multiple points as inputs. – GBG Jun 30 '17 at 18:50
  • What parameters have you used as far as ObserverA and B are concerned? – NewAtGis Jun 30 '17 at 18:50
  • If you run the Viewshed tool on the high point, it will return all the areas that are visible from the high point. Doesn't that by default also mean that the high point is visible from those areas? – J.W. Powell Jun 30 '17 at 18:51
  • In this scenario, every cell in the raster would be a potential observer. I'll need the output to display values for those cells that can view the high point (1) versus those cells that cannot (0). – Nathan Herzog Jun 30 '17 at 19:33
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    Hillshade? Don't you want to use a DEM as the raster? If you've been using hillshade, there's your problem. You need surface elevation data as your raster. Hillshade is just nothing more than pretty shadows cast by the sun. – J.W. Powell Jun 30 '17 at 20:23