[postgis-devel] [PostGIS] #1058: [raster] Two-raster spatial operations framework proposal

[PostGIS]

#1058: [raster] Two-raster spatial operations framework proposal
----------------------------+-----------------------------------------------
 Reporter:  bnordgren       |       Owner:  pracine      
     Type:  enhancement     |      Status:  new          
 Priority:  medium          |   Milestone:  PostGIS 2.0.0
Component:  postgis raster  |     Version:  1.5.X        
 Keywords:                  |  
----------------------------+-----------------------------------------------

Comment(by bnordgren):

 Replying to [comment:9 mcayland]:
 > > > 5) Rework postgis/lwgeom_transform.c cache code so it uses the
 underlying liblwgeom routines... and while you're there, also refactor it
 into a simple API so that adding caching to any other functions within
 PostGIS (as in linked with PostgreSQL) becomes much easier (and indeed, I
 believe you can test this by making the prepared geometry cache use your
 new code too).
 > >
 > > Do you see a way to avoid making this link?
 >
 > I think so? I was suggesting refactoring the reprojection code and
 moving its core into liblwgeom. Since raster already depends upon
 liblwgeom, then the problem is already solved and all other users of
 liblwgeom can also benefit from the revised functionality.

 There may be a couple of problems here. First, the cache seems to make use
 of "MemoryContext", which I believe is a postgresql structure. Presumably,
 this is to ensure that things which are allocated are free-ed at the end
 of the call. However, they seem to be storing at least a little state
 information in there too.

 Second, raster needs access to more than just the "core code". It also
 needs access to the code that retrieves the proj4 string from the
 spatial_ref_sys table. If we can't find a way to link raster to postgis,
 we'll have duplicate code in both libraries.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1058#comment:10>
PostGIS <http://trac.osgeo.org/postgis/>
The PostGIS Trac is used for bug, enhancement & task tracking, a user and developer wiki, and a view into the subversion code repository of PostGIS project.