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Showing posts from February 17, 2008

Python Mapscript Tricks

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I mentioned previously a site which uses google maps with a WMS. The problem with using points (or labels) in a tiled application such as google maps, or OpenLayers is that each tile can only draw its own contents. So if you draw a point with a radius of 10 pixels whose center is 2 px away from the edge of the tile, then 8px of the entire 20px will be chopped. By default, those lost 8 pixels will not be drawn in the adjacent tile because the center of the point does not fall in that tile. so that gives something that looks like this for 2 adjacent tiles: It's hard to even tell that those tiles belong together! Using some python mapscript and PIL , it's pretty simple to make those look like this( except I dont know how to tell blogger not to add the spacin...) : That's actually the same WMS request(s), just changing the call from a simple WMS CGI script that calls mapserver to a WSGI script that uses python mapscript and PIL. The script: 1. takes the current bounding bo

Open Source GIS

Just saw this linked from Sean's post . The quotes in there are absurd. But reminded me there's an important point in favor of OSS that I haven't seen. You can still get help directly via the email list or IRC from F Warmerdam , it's primary author. Likewise for the developers of Mapserver and OpenLayers and PostGIS . I wonder if the lead developers of ESRI products spend their off-time perusing the forum's or mailing lists and answering questions? ( I don't know, they may. But I suspect not. ) There's something to be said for enjoying what you do. And I think that's very true in the case of those in the open-source community. Happy coders make better software. Any programmer that denies that will leave me flabbergasted. I just don't understand how I could be effective only clicking the menus that were provided to me if I chose a black-box solution. But, call me crazy, I like linux. Also, in these parts, if you lock your single-speed bike to a woo