Raster Support

[Denis Lalonde]

Hello all;

I've got a small PhpMapScript (mapserver4.8.1 php5.1.2) app running on my XP machine with IIS and have run into a few questions regarding Raster support.

I’ve got 300 tiff tiles of my area. I also have a (large!) 818meg MrSid version of the same data.
I have a MAPFILE containting 2 of the 300 tiles and define them as:

LAYER
    STATUS ON
    NAME 'MYORTHOtest'
    TYPE RASTER
    DATA "blahblah\filename.tif"
END

My OUTPUTFORMAT in the MAPFILE is defined as:

OUTPUTFORMAT
    NAME png
    DRIVER "GD/PNG"
    MIMETYPE "image/png"
    IMAGEMODE PC256
    EXTENSION "png"
END

Now Questions:
1 - Displayed with the above outputformat, the resulting image quality is poor. I’m not sure what the correct terminology is, but it doesn’t seem like it is using all the colors it should. If I change my Output format to Jpeg, the resulting image appears great...although performance seems affected. All other output formats result in "poor" image quality too. What am I missing?

2 - While "panning" around my map, if I get to the "edge" of one of the tiles displayed in the map, I get the following PHP error:"Warning: [MapServer Error]: IReadBlock failed at X offset 9, Y offset 39: GDALRasterIO() failed: drawGDAL()"
If I’m zoomed into the tile enough so that it fills my map, or that the entire tile shows in the map, then I don’t get an error. What is causing this?

3 - I've searched, but didn't find anything regarding MrSid in PHPMapScript. It's not supported correct?

Regards,
Denis

Denis Lalonde 
Engineering, Environmental and Construction Services
City of Cornwall
P.O. BOX 877, 1225 Ontario Street
Cornwall, Ontario K6H 5T9
dlalonde at city.cornwall.on.ca
I

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