[OSGeo Oceania] Geowebcache tile naming scheme

[Alex Leith]

Hey Adam

Here's a discussion on the file naming for GWC:
https://sourceforge.net/p/geowebcache/mailman/geowebcache-users/thread/28819540.post%40talk.nabble.com/#msg25474083

Looks like the plan was `
layername/projection_z/[x/(2^(z/2))]_[y/(2^(z/2))]/x_y.extension`

But then it changed along the lines of: "the bit shifting starts with 2,
effectively making it `2^( 1 + ( z / 2 ))` And there's some zero-padding."

Personally, I think re-implementing the cache creation process in Python
will be rather tedious and there will be a lot of mess between generating
the data and having it 'just work' in GeoServer.

I'll ping you on Slack ;-)

Cheers,




On Wed, 24 Apr 2019 at 10:08, adam steer <adam.d.steer at gmail.com> wrote:

> Hi Oceanians
>
> is anyone out there extremely familiar with geowebcache’s tile naming
> schemes - for example given a grid schema what are the decisions behind how
> map tiles are named?
>
> Essentially given a grid schema declaration and a bunch of imagery I need
> to replicate what GWC does in Python. …and unfortunately gdal2tiles / the
> OSM tile naming code doesn't use the same tile naming / indexing schema (it
> needs to match exactly an existing tiling schema - which is custom, and I
> haven’t managed to decrypt yet).
>
> What I’m missing is a likely small but very critical piece of logic which
> will let me map from geographic bounds to tile index locations, for example
> from:
>
> input_tiff(minx miny maxx maxy) -> /zoomlevel/????/????_????.png
>
> …for output tiles in EPSG4326 (plate carree), indexed to lower left corner.
>
> I’ve been digging into Geowebcache code, but Java does my head in and the
> wormholes get too deep in there. I can’t find any documentation which
> really explains well how this mapping is done.
>
> I have a small budget for an hour of your time; alternately feel free to
> respond in public and I will buy you beer/dinner/give good mojo to FOSS4G
> SotM Oceania.
>
> Thanks!
>
> Adam
>
> --
> Dr. Adam Steer
> http://spatialised.net
> https://www.researchgate.net/profile/Adam_Steer
> http://au.linkedin.com/in/adamsteer
> http://orcid.org/0000-0003-0046-7236
> +61 427 091 712 ::  @adamdsteer
>
> Suits are bad for business: http://www.spatialised.net/business-penguins/
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>


-- 
Alex Leith
m: 0419189050
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