[OSM-talk] NPE map WMS server projections

[Simon Hewison]

Nick Whitelegg wrote:

> Can anyone suggest any guidelines as to how I would go about correcting 
> this (as, I have to admit, I'm a bit unsure?) At the moment the WMS server 
> just "glues together" the appropriate NPE tile images based on the 
> bounding box, width and height. I guess, therefore, that this is an 
> inherent problem in the accuracy of the NPE tiles.
> 
> Would it involve something like "twisting" the tile so the longitude of 
> the top and bottom are equal?

I think the phrase your are looking for is "rubber-sheeting" or "affine 
transformations", in which you piece together the source tiles after 
putting into the destination image after calculating the OSGB to lat/lon 
transformation on each corner of the image, and whatever image library 
you are using that does the transformation will stretch the image to fit 
into the polygon that the grid square maps to.

http://www.geog.ubc.ca/courses/klink/gis.notes/ncgia/u28.html

-- 
Simon Hewison