queries

[Erick Ferreira]

Hello,

In our current project, we need to write a service layer - a dynamic library in C that exposes some raster utility functions. 
For that, we are trying to use only the exported mapscript symbols (from libmapscript.so).

One of the functions we have to expose in our library is supposed to fetch the raster values of a given layer band that lie on a given line segment described in map coordinates.

Map Server 4.8.1 does not support a msRasterQueryByLine() method. Also, even the msRasterQueryByShape() function in fact queries the whole bounding box of the polygon, not the polygon itself. 
We found that the most obvious top level implementation of our feature would be accomplished by iterating over rasterQueryByPoint() on a Bresenham line-drawing algorithm basis.
Our tests proved the performance to be really inappropriate in this implementation, as expected.

We would like to share our problem, maybe someone has a good feedback for us. 
We are also considering extending MapServer ourselves to support msRasterQueryByLine() 

Thanks,
Erick