The pixelSize is used to relate pixels on a hypothetical screen to scale. The particular choice of 0.28mm/pixel is explained n section 7.2.4.6.9 of the WMS 1.3 standard, which I encourage you to read.
If I remember correctly, pixelSize only matters in GWC if you define the levels of the pyramid in terms of scale. WMS and tile services produce images that have height and width in terms of pixels, so you can't "create a 96dpi image"*. It will be 256x256 (or whatever you set it to), and the actual DPI will depend on the screen that you show it on. Are you defining your pyramid in terms of scales or in terms of resolution for each level? If the latter, how did you calculate the appropriate resolutions? -Arne *: If you tell GeoServer to assume a different DPI, it will affect how big it renders fonts and other things defined in terms of "points", but it doesn't really affect how geometries are rendered on tiles. On 8/14/12 03:06 , Michael Smith wrote: > I am using GeoServer 2.2-RC2 to set up tiled map services using the > integrated GWC. I can view the service through the GWC demo page and am able > to view the service using EPSG:26910 based tiles. The tiles are successfully > created in the proper directory (I am not using the data_dir directory). I am > also able to add and view the tiled service in QGIS and via WMS GetMap > requests in browsers on multiple computers when accessing GeoServer tile > services only. > > The problem occurs when trying to add it to the map application I am working > on. The tiled map service coming from GeoServer fails with a message about > the resolution exceeding the allowable threshold. I see from the > documentation that a pixelSize of 0.28mm/pixel is assumed (a little over 90 > dpi). Following another thread regarding resolutions, I changed pixelSize in > geowebcache.xml to 0.0002645833333333333333333333 as they wanted tiles > created with 96 dpi. Is that the correct pixelSize value for creating a 96 > dpi image? > > Also, is geowebcache.xml the correct place to make such a change? I noticed > that GeoServer automatically changed the value back to 0.28 mm/pixel. > > I am beginning the transition from ArcGIS tile services to open source and > still need to be able to use all our existing tile services. ArcGIS defaults > to 96 dpi and so all our existing tile services are configured as such. > > I think the resolution and scale differences between GeoServer and ArcGIS is > where things are going wrong. In trying to match the numbers between the two > tile sources, I can match either the scale or resolution for the different > tile levels, but not both. Depending on which it is that I match it to > (resolution or scale), the percent difference in the error is different so I > think dpi is key. Does it seem reasonable that if I can change GeoServer to > work with a pixelSize that creates a 96 dpi image the resolution error will > go away? > > - Michael > > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Geoserver-users mailing list > Geoserver-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geoserver-users ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
