Can I calculate the area of the "visible" in viewshed?

721
4
06-14-2013 12:35 PM
SaraThompson2
New Contributor
I'm trying really hard to figure out how to calculate the area of the "visible" portion of my viewshed analysis. Geometry calculator is greyed and unavailable for some reason. Do I transform the data into something else? It's not being considered a polygon or a feature class so normal area finding techniques aren't an option. Please help. Thank you!
Sara
0 Kudos
4 Replies
EricRice
Esri Regular Contributor
Give Zonal Geometry as Table a try. Or convert your viewshed raster into polygons and calculate area as you normally would.

Best,
Eric
0 Kudos
DarrenWiens2
MVP Honored Contributor
Is it greyed out because it's the auto-calculated Shape_Length field? You can't calculate that.

There are many ways to get the area, and it sounds like you've tried a few, but here are a couple more.

1.) Dissolve your polygons based on whether it's visible or not. If it's in a geodatabase, Shape_Length will show you the total.
2.) If your polygons are in a geodatabase, you can use Summary Statistics to group based on visible or not (case), and sum the Shape_Length.
0 Kudos
markdenil
Regular Contributor II
The viewshed output has cell values equal to visibility from the input observation points (vew points).
Thus, all visible cells have value > 0,
and the count of all cells with value > 0 times the cell area, equals the visible area.
0 Kudos
SaraThompson2
New Contributor
Zonal geometry as table worked great and then I used tabulate area to find how much of my polygon was within that area. Thanks for the help 🙂

Sara
0 Kudos