topic line of sight in 3D Questions

line of sight

PatrickDornberger — Tue, 20 Dec 2011 17:23:29 GMT

hi there

i've got two areas and wanna know which points of one of these areas can i see from the other one (eye level Z=1.7). with the "line of sight" tool can i only show lines between two dots, but i like to know all points i can or can't see in area (polygon vector or raster) out of the other area (polygon vector).
how is that possible? and how have i to do this?

thx!

Re: line of sight

PrasantaBhattarai — Tue, 20 Dec 2011 22:14:59 GMT

There might be different ways to do it. Here's what came on my mind:
Use Viewshed tool to create a viewshed raster.
- Use All points of one of the areas as observer point feature. You can add OFFSETA field and add 1.7 for observer offset. (Here's more on Using Viewshed and Observer Points for visibility analysis)
- Output from the Viewshed tool is a raster which you can use to see how many points from your target area fall under the visible/non visible area.
- If you look into the output raster attribute table, the Value will tell you how many observer point can see that particular area, but it is not possible to tell which observer point can see what area/target point.
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If you are using 10, you can Iterate feature (observer points) and create individual Viewshed raster. This way, you can tell which which point from the target fall under visible/not visible area for a particular observer point.
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Hope this helps!!

Re: line of sight

PatrickDornberger — Wed, 21 Dec 2011 05:45:07 GMT

thanks!
i will try... :confused: (GIS-beginner) 😛