GeoWebCache Configuration

I’ve long delayed the configuration of GeoWebCache (GWC).  Automatic configuration within GeoServer’s deployment of it has been adequate until now.   Until now that I want to deploy tiles in something other than Google Mercator… .

I’ve developed a cache setup for Ohio State Plane North, Feet (epsg:3734).  At first it was a going to be a cache just for our service area, then I thought I’d include surrounding counties, and by the time I was done, I just decided that having a cache definition for the entire state plane ohio north coverage area made as much sense as anything else– it could make things easier to share and integrate as part of a regional standard for WMS-C, assuming I get buy-in from others… .  It could also be easily adapted for State Plane South.

The definition for a cache requires three things:  coordinate extent, resolutions (or equivalent), and tilesize (height and width).  For coordinate extent, I chose the extents of epsg:3734 as defined by spatialreference.org, and snapped them to the nearest 5000 foot interval:

1320000

160000

2525000

976000

Then, choosing resolution based on a series of measurable scales (1:600 or 1″=50′, 1:1200 or 1″=100′, etc) we get the resolutions:

918.6351706036746

229.65879265091866

58.20472440944883

45.931758530183735

29.102362204724415

22.047244094488192

14.220472440944883

11.023622047244096

8.818897637795276

8.267716535433072

5.511811023622048

4.409448818897638

2.204724409448819

1.1023622047244095

0.5511811023622047*

Finally, we’ll use a predictable tilesize:

<tileHeight>256</tileHeight>

<tileWidth>256</tileWidth>

Now we have a portable tilecache recommendation that should work for all of Northern Ohio:
GWC Example

3 thoughts on “GeoWebCache Configuration

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