[OSGeo-Standards] WMTS and TMS opposing grid origins (top-left vs bottom-left)

[Jason Lee]

Thanks Raj,
I can understand the reason why the top-left is the origin but was hoping
the standard was perhaps flexible enough to allow setting of alternative
origins given the historical reference to TMS.

I've actually setup a rewrite rule at the tile server to "invert" the
y-value to handle the difference so it is not such an issue now (only
slight calculation overhead on the server).

Jason



On 6 December 2013 17:09, Raj Singh <rsingh at opengeospatial.org> wrote:

> I asked some of the WMTS experts in OGC and here's a paraphrase of the
> response I received.
>
> "Integer-based coordinate systems are usually oriented starting 0,0 at the
> top left.  It especially makes sense when they're meant to be linearly
> mapped to screen/image pixel coordinates (which has 0,0 at the top left).
>  It's the way WMS GetFeatureInfo I,J is oriented, and the way Google Maps
> tiles are oriented.  I believe it's also the way ArcGISMap tiles are
> oriented.  TMS appears to be the exception."
>
> ---
> Raj
> The OGC: Making location count.
> http://www.opengeospatial.org/ogc/organization/staff/rsingh
>
>
> On Dec 5, at 5:06 AM, Jason Lee <jaslee.st at gmail.com> wrote:
>
> > Hi,
> > I've set up some map tiles in a non-Web Mercator projection and have
> rendered them with tile numbering starting in the bottom-left - just like
> that in the TMS format and suitable custom scales (NOT half on each
> successive zoom level).
> >
> > I've be able to successfully consume the tiles in an OpenLayers
> client..However, I've been looking at how we can bring these tiles into
> ArcGIS desktop via WMTS and I see that this OGC standard assumes a grid
> origin starting at the top-left - is that right? ...my tiles are mixed up
> when attempting to consume them in ArcGIS.
> >
> > Why does WMTS have tile number origin at the top-left when the previous
> TMS started in bottom-left? Is there syntax in WMTS to make it start in
> bottom-left like in TMS?
> >
> > Thanks
> >
> > Jason
> > _______________________________________________
> > Standards mailing list
> > Standards at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/standards
>
>
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