topic Viewshed Analysis in ArcGIS Spatial Analyst Questions

Viewshed Analysis

IkechukwuNwaiwu — Sun, 22 Nov 2015 18:35:26 GMT

I'm trying to run a viewshed analysis of building. My original building layer was a vector which had height attribute. i converted this to raster and added my elevation layer to my building raster layer. i used the output raster "DEMBuilding" as the input for my viewshed analysis but keep getting a NODATA error for the 'DEMBuilding' layer.

Any suggestions???

Re: Viewshed Analysis

ChrisDonohue__GISP — Sun, 22 Nov 2015 21:27:06 GMT

For starters, it appears from the error message that there are a several issues. First, all the cells in the Int_Building raster are currently "No Data". I would check that raster to see if this is indeed true. If that is your surface raster, you need to remedy it so it has elevation values. Second, the Viewshed tool is not finding a valid observation point. Note that the observer location needs to be a point or polygon feature (not a raster). I'd review the characteristics of observation locations and ensure that what you have set up matches what the process expects.

After looking into these two, I'd run the process again.

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Chris Donohue, GISP

Re: Viewshed Analysis

IkechukwuNwaiwu — Sun, 22 Nov 2015 21:39:28 GMT

The original building raster was a floating point raster which i converted to integer to confirm there were no NoData values...none found. Also i have used my main DEM raster with my observation feature (factoring in OFFSETA and OFFSETB parameters) to compute the viewshed, no problems there either.

Re: Viewshed Analysis

ChrisDonohue__GISP — Sun, 22 Nov 2015 21:56:19 GMT

Part of the error message states "All Cells in the Raster Int_Building have the NODATA value." What is "Int_Building" and how did you use it in the viewshed analysis? Any chance when you ran the Viewshed the wrong elevation raster was used (i,e. Int_Bulding was used when DEMBuilding should have be used instead?

Also, a suggestion. Capture a screenshot of the tool inputs just before you run it and post it to this thread. This will help folks see the details, which will then help in evaluating what may be going awry.

Chris Donohue, GISP