On Wed, Jul 17, 2013 at 12:32 AM, Greg Troxel <[email protected]> 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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