[Tiling] Fwd: [OSGeo-Standards] Irregular tile coverage in TMS?

[Oliver Tonnhofer]

Hi,

On 12.09.2010, at 13:33, Mateusz Loskot wrote:
> I understand the size and spacing constraints.
> What I'm missing, however, is what TMS says about "topological"
> regularity of tiles within a coverage.
> 
> I attached basic drawing with two example tile coverages:
> 
> a) blue - regular coverage, rectangular
> 
> b) red - irregular coverage
> 
> Is only blue version kosher for TMS or both versions are valid?

It should be valid if your grid size at this level is 4x4 and if you are returning empty/transparent images for tiles outside of your coverage. An optimization would be to return 301/302 and point to an empty image with long expire time, but I don't know how redirects are supported in non-browser clients.

You've got the same problem with WMS/WCS where you can only define a bounding box in the capabilities. Requests outside of the coverage are transparent, or only contain the background color.

Regards,
Oliver