Friday, February 29, 2008

Project Geoserver

i have setup a geoserver on tomcat on a local server (Debian). Its pretty easy, probably even easier than installing a notepad replacement.
Data configuring took some time to make sense. I had been working with UMS mapserver for a couple of weeks and all that R&D on .MAP files was pretty useful in writing styles for geoserver layers. Although my job was only limited to finding the possibilities and limitations of geoserver WMS.
Setting up tilecache was probably the "hardest" part of this project since all the data was in espg:4326 (ie longitude,latitude) but the request is in a custom format which is not directly related to anything used by any other application like say openlayers. So a few days of a lot of long double/float values, variables with even longer names, writing down outputs and staring at them for some pattern.. later i ended up with a php script with took our input and gave out a tilecache request. Also out tiles started at some displacement and had a different degree/pixel ratio than standard, so even that was a tricky bit since the output had to fit exactly on our tiles

Outstanding problems:
1. i am wondering whether geoserver lacks on-the-fly line join cuz my highways (which are multiple line segments) are displayed with rough edges. This doesnt happen in UMS mapserver by the way. I did manage to join simple roads with line end property but this doesnt work too well with roads that have more than one style(roads with boundries etc.)
i probably will have to run scripts to join all my roads in the database itself but then i wonder whether my queries will be affected since even to display a pixel of road, the query will return the whole road instead of a smaller segment as it does now. (maybe postgis handles this case, maybe it doesnt)
2. Geoserver buffer support doesnt seem to work as well as i would have hoped. even with a few labels i see tiles cutting text. I am using metatiles too. Maybe im not using the right buffer settings. There are a lot of style examples for geoserver but most of them address the same kind of prolems and use the same old simple style options.
I might write one myself when I get some time.

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