[GRASS5] GRASS extensions build system, r.cva

[Paul Kelly]

On Wed, 16 Mar 2005, Benjamin Ducke wrote:

> It seems to me, that three path variables in the original
> make system control where things take place
>
> Source directory (SRCDIR): this is the starting point for locating include files and libs?
> Build directory (DSTDIR): this is where the object files are stored?
> Installation directory: this is where the final executable modules are copied to.
>
> Am I right about the meaning of these?

Yes that sounds right. I suppose at one stage the thinking was that you 
wouldn't need to re-run configure as you would assume the platform that 
the binaries were installed on was similar enough to the one that they had 
been compiled on, and including Platform.make in the binary distribution 
would be enough.

But if you are running configure why a cut-down one? What sort of things 
are you leaving out and why? This is an interesting little project.

> In other news:
>
> A new version of r.cva (cumulative viewsheds) for GRASS 6 is now finished and has been
> tested. I have contacted the original author, Mark Lake, about the possibility of
> releasing it under a GPL compatible license. I have not got an answer so far, but
> I am told that Mark is really busy these days and I am sure he will look into this
> and we will find a good solution for making r.cva more accessible to GRASS users.

That is really good news (although there was not much wrong with the 
original r.cva if you could live with having to frequently do little bits 
of data pre- and post-processing with r.null, s.to.rast etc.)

There was a paper in Photogrammetric Engineering & Remote Sensing a year 
or two ago (from CERL, actually) about a new very fast way of doing 
viewshed analysis that sounded like it would be a very nice project to 
implement using a vector graph structure to show direct paths between 
raster cells, and to make calculations using the Directed Graph library. 
But an accessible r.cva would make the line of sight capabilities in GRASS 
very usable indeed.

Paul