[mapserver-users] RE: Image Pyramid with gdal_retile and two UTM zones

[Rahkonen Jukka]

Hi,

Use the -dstnodata parameter with gdalwarp http://gdal.org/gdalwarp.html
Then use the same value in LAYER OFFSITE http://mapserver.org/mapfile/layer.html
Note that this works perfectly only if the warped images are in some lossless format. In jpeg, ecw etc. the nodata gets also slightly different RGB values and some pixels are then not transparent in Mapserver.

I have never tried alpha channels for masking the nodata area and I can't say it works with Mapserver.

-Jukka Rahkonen-
________________________________________
aphunter wrote:

> Hi there. I used gdalwarp to warp one of the zones into the spatial reference
> system of the other, and everything lined up. The only issue now is that
> each image seems tilted, and so there is a lot of black space on the warped
>pyramid.

> Is there any way to prevent this from happening?

> http://osgeo-org.1803224.n2.nabble.com/file/n6825717/out.jpg

> http://osgeo-org.1803224.n2.nabble.com/file/n6825717/noalpha_m_3211401_ne_11_1_20090525_1_1.jpg

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