Hi, I think it is exactly as Ed says. I got similar kind of problems once when I started to reproject images with "gdal_translate", and mosaic and cut the reprojected images to suit mapsheet system of the destination projection. With gdal_translate I can get rid of those white (in my case black) pixel lines by using a GDAL virtual format (.vrt)as a source data set instead of individual files. I have been thinking that this means in practise building a mosaic before reprojection, thus there is no place in the process where those lines would be formed. Judged by the result you get I guess that maybe the tileindex system in Mapserver is handling each tile separately and not in the same way than GDAL is handling VRT. If getting rid of those lines is important for you it might be worth trying to use GDAL virtual data set as source data for your Mapserver instead of tileindex. There has been a link to a modified "gdal_merge.py" script in the gdal_dev mailing list possible in May 2005, but I could not find the link right now. With that script you can make a virtual data set from a bunch of original image files, and after creating pyramid layers for the vrt-file (this will be slow if your VRT is large) it is quite usable for Mapserver. Regards, Jukka Rahkonen <http://xserve.flids.com/pipermail/gdal-dev/2005-May/008605.html>
________________________________ Lähettäjä: UMN MapServer Users List puolesta: Ed McNierney Lähetetty: ti 14.3.2006 16:38 Vastaanottaja: [email protected] Aihe: Re: [UMN_MAPSERVER-USERS] Problem with reprojected images Dirk - I assume your tiled source images do not overlap, and that the originals do not have white border strips around them. If that's the case, this may be an inevitable artifact of the reprojection. Look at the situation along one north/south edge between two tiles. If you render the tiles in the source projection you'll get two adjacent vertical lines along the edges of each file, with no gap between them. If you reproject the tiles, then you will have two adjacent edges that are two diagonal lines. The distance between the edges may not be 1, and may vary by a pixel along the course of those two diagonal lines. When that happens, the images will sometimes overlap by one pixel (you won't notice) and will sometimes leave a one-pixel gap (which is obvious). The obvious gaps will repeat in a regular pattern since the phase difference between the two diagonal lines will be regular and repeating. - Ed Ed McNierney President and Chief Mapmaker TopoZone.com / Maps a la carte, Inc. 73 Princeton Street, Suite 305 North Chelmsford, MA 01863 [EMAIL PROTECTED] (978) 251-4242 -----Original Message----- From: UMN MapServer Users List [mailto:[EMAIL PROTECTED] On Behalf Of Dirk Jesko Sent: Tuesday, March 14, 2006 3:04 AM To: [email protected] Subject: [UMN_MAPSERVER-USERS] Problem with reprojected images Hi, I set up a WMS for aerial images. The images are projected in Gauss-Krueger 3 and have a size of one square kilometer. The WMS also provides other projections, e.g. Gauss-Krueger 2-5, UTM, etc. If I query the WMS with a projection other than the original one, I get little white lines along the edges of the tiles (see the attached image). The image format does not matter. How do I get rid of these? I can not find any option that might be related to this. By the way, this also happens if the data is accessed via mapscript or as normal cgi. Thanks for any help. Regards, Dirk Here a part of the mapfile: MAP ... IMAGECOLOR 255 255 255 EXTENT 3100000 5200000 4100000 6200000 SIZE 500 500 SHAPEPATH "/data/daten/WMS" PROJECTION "init=epsg:31467" # GK 3 END WEB METADATA ... "wms_srs" "EPSG:31467 EPSG:31466 EPSG:31468 EPSG:31469 EPSG:32632 EPSG:32633 EPSG:4326" "wms_encoding" "UTF-8" "wms_feature_info_mime_type" "application/vnd.ogc.gml" END MAXSCALE 10000000 MINSCALE 1000 ... END OUTPUTFORMAT NAME png24 DRIVER "GD/PNG" MIMETYPE "image/png" IMAGEMODE RGB EXTENSION "png" FORMATOPTION "INTERLACE=ON" END OUTPUTFORMAT NAME png DRIVER "GD/PNG" MIMETYPE "image/png" IMAGEMODE PC256 EXTENSION "png" FORMATOPTION "INTERLACE=ON" END OUTPUTFORMAT NAME jpeg DRIVER "GD/JPEG" MIMETYPE "image/jpeg" IMAGEMODE RGB EXTENSION "jpg" FORMATOPTION "QUALITY=95" FORMATOPTION "PROGRESSIVE=ON" END ... LAYER NAME "img02000" GROUP "img" TILEINDEX "IMG_02000.shp" TILEITEM "locationUn" TYPE RASTER MAXSCALE 500000.0 MINSCALE 100000.0 PROJECTION "init=epsg:31467" # GK 3 END METADATA ... END END ... END
