[postgis-users] Calculating line of sight

[David Rowley]

On Wed, Jul 17, 2013 at 12:32 AM, Greg Troxel <gdt at ir.bbn.com> wrote:

>
> Also, for distances of more than a few km, you should take earth
> curvature into account.  I am unclear on how that's handled in postgis.
> Perhaps if you convert each point to X,Y,Z then straightforward 3D
> calculations will be right.   But using a projected coordinate system
> such as UTM and elevations will be off.
>

I did struggle to find examples of things out there that would help me
calculate the line of sight.

I wrote this blog to help anyone else who needs something similar.

http://davidrowley.blogspot.co.nz/2013/08/calculating-line-of-sight-with-postgis.html

If anyone can see something where I could have implemented something using
a core PostGIS function but I did something manually, please let me know.

Also I did use PostGIS 2.1 here as I'm still testing. 2.1 will be release
before I'm ready to go live. So it's not an issue.

Regards

David
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