topic Re: Viewshed output trouble in 3D Questions

Viewshed output trouble

ScottRowland — Fri, 15 Nov 2013 22:37:30 GMT

Hello, The typical output of the Viewshed tool in ArcToolbox is a raster image with DNs of 0 (not visible) and 1 (visible). Today when I ran the tool, the output was 0 (not visible) and 1-7 (visible). This makes converting the raster to a polygon shapefile a hassle. Does anybody know what I might have inadvertently changed so that I now get this different output?

Mahalo.

Re: Viewshed output trouble

ThomasHelin — Sat, 16 Nov 2013 18:57:50 GMT

Hi
I don't have an explanation to what could have caused the result you describe but if you are sure of the output (0=out of sight and values between 1 and 7=visible) I suggest you use the Raster Calculator to change the values for all the visible cells to 1. After this it's easy for you to convert the raster to polygon.
Regrads,
Thomas

Re: Viewshed output trouble

OriIsenberg — Sun, 17 Nov 2013 07:19:23 GMT

Hi Mahalo
output results:

0 = not visible
1= visible from one observer points
2 = visible from 2 observer points.
3= (and so on....)

I would also suggest to extract only values bigger then 0 with raster calculator using "CON" function, or use the model builder and with selection iterator to run the viewshed independently to each point and not to all of them together, in that way you will have the coverage of each point and you can merge the results later.

Re: Viewshed output trouble

ThomasHelin — Sun, 17 Nov 2013 13:50:41 GMT

Hi again,
I think I was a bit tired when I wrote my answeer yesterday since I mixed up the tools. What I meant was to use the Reclassify Tool in the Reclass toolbox.
Sorry if my mistake confused you.
Thomas

Re: Viewshed output trouble

ScottRowland — Tue, 19 Nov 2013 01:01:17 GMT

Hello Ori,

Your answer allowed me to figure out what I'd done wrong. Specifically, I used a point shapefile with multiple features rather than one with only one feature.

Mahalo,
Scott

Hi Mahalo
output results:

0 = not visible
1= visible from one observer points
2 = visible from 2 observer points.
3= (and so on....)

I would also suggest to extract only values bigger then 0 with raster calculator using "CON" function, or use the model builder and with selection iterator to run the viewshed independently to each point and not to all of them together, in that way you will have the coverage of each point and you can merge the results later.