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
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.
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.