Best Practice question about Raster Viewshed Analyses

JenniferHan — Tue, 27 Mar 2012 16:55:50 GMT

Hello,

I had a question about what should be the best approach when it comes to doing Viewshed Analyses.

Premise of project: Where are the towers visible? (Point Shapefile with hundreds of discrete points representing towers along a linear route). OFFSETA = tower height and OFFSETB = person height who will see the tower.

I was able to download elevation data with resolution of approx 10meters. Instead of one large file for the extent, I was given 6 smaller chunks (due to size).

My dilemma lies in the viewshed analyses. The point shapefile lies on all 6 small rasters. However, I noticed that, let's say tower 1 that lies on raster A, cannot be processed on raster B because it does not lie on raster B (or this is my conclusion because when I try to run a viewshed of a selection of points that do not lie on top of the raster, it fails).

My solution was to automatically combine all the rasters using a mosaic dataset. However, I understand that now the problem becomes processing capacity.

Is there a way around this problem? Do I just need to combine all 6 rasters to 1 to get an accurate viewshed of all the discrete points in the shapefile? Is there a best practice approach to this issue?

Thank you!

Re: Best Practice question about Raster Viewshed Analyses

JeffreySwain — Wed, 28 Mar 2012 10:36:23 GMT

What do you mean 'processing capacity'? Are you referring to how much processing your computer can handle? How large will the mosaicked raster be? The mosaic dataset should work fine as the input for the viewshed tool itself. You should not need to convert it to a physical raster. I have used them in testing before and not had a problem.

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Best Practice question about Raster Viewshed Analyses

Re: Best Practice question about Raster Viewshed Analyses