[Mapserver-users] Re: TRANSFORM question

[Tyler Mitchell]

Just noticed you probably meant to change the subject, mapguy.  So I'm 
reposting this for you.


mapguy <phatsbbnlist at twcny.rr.com>  wrote on 05/20/2004 01:55:08 PM:

> A question on TRANSFORM and related matters. ALL files verified as much 
> as possible (`gdalinfo`, `ogrinfo` , GIS, etc):
> 
> I have some "init=epsg:26918"  (UTM 18N GRS80 NAD83) rasters  in  a tile 

> and some "proj=latlong"  ( decimal degree ... derived from UTM NAD 83 
> GRS80 I believe the metadata implies) data in a line shapefile. They 
> plot perfectly.
> 
> I have "init=epsg:32115" (New York State Plane, Transverse Merc with 
> false northings and eastings) rasters in a tile and the same shapefile 
> as above, both in its original projection and in a state plane 
> conversion using ogr2ogr.  Things don't seem so perfect.
> 
> The shape file is roughly 1/4 the size and 150 miles or so SW (3 region 
> diameters essentially) of the place and size it should be, i.e. 
> surrounding the tiled state plane rasters, and the associated quadrangle 

> lines from plotting the tileindex shapefile as a vector layer. Either 
> projection of the shape file works if I set the projection parameters 
> correctly in the map file. Either disappears if I set the wrong 
projection.
> 
> the TRANSFORM doesn't seem to matter (though the online docs mention 
> both "ON/OFF" and "TRUE/FALSE" in different places, and I tried both)
> 
> Is there a reasonable explanation as to why these files are plotting 
> this way?  I mean, do false northings and eastings have to be added as 
> PROJECTION block params, or something like that? Does/How does TRANSFORM 

> work "on the fly", i.e. is there more to it than NOT putting TRANSFORM 
> FALSE/OFF in a layer?