[mapserver-users] WMS and PROJ

[Daniel Morissette]

Paul Ramsey wrote:
> 
> When I set up my WMS server with projections, it correctly creates
> <LatLonBoundingBox> entries for the layers. The <LatLonBoundingBox> for
> the whole server is based on the EXTENTS given in the map file: if one
> of my layers has an extent larger than the EXTENT in the map file, I can
> have an overall extent smaller than one of my layer extents... does the
> spec have anything to say about this minor inconsistency? Is the overall
> <LatLonBoundingBox> supposed to be the superset of all layer extents?
> 

I think it would make sense that the root layer's bounding box should be
a superset of the bounding box of all the layers in the mapfile.  I
haven't seen a mention of this in the spec but I would think that it is
implied since it just makes sense.

This being said, in the MapServer case the root layer's bounding box is
derived from the MAP EXTENT as you pointed so it is up to the person
setting up the mapfile to make sure the global extents are valid.  I
guess we could have MapServer scan the extents of all layers but it
never looked necessary to do so since the info is already there in the
mapfile.

About layer extents, the default behavior for vector layers is that
MapServer will look at the individual layers and open the data source to
fetch the extents.  If that default behavior doesn't work or gives
extents that are too big, then you can use the "wms_extent" layer
metadata to specify your own extents.  The use of the wms_extent layer
metadata is currently required for raster layer since MapServer
currently has no way to fetch raster extents automagically (on the ToDo
list).


BTW, talking of WMS... we put the last touches to the WMS-HOWTO today...
we were waiting until it's available on the UMN website to announce it
but I can't wait... and I know lots of you can't wait either... so for a
sneak preview, go to:
  http://www2.dmsolutions.ca/tmp/WMS-HOWTO.html

-- 
------------------------------------------------------------
 Daniel Morissette               morissette at dmsolutions.ca
 DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------
  Don't put for tomorrow what you can do today, because if 
      you enjoy it today you can do it again tomorrow.