Hi, I have not played with either lately. At least one difference is that gdal_merge.py can't warp images. Gdalwarp has also lots of more options. Long time ago I used modified gdal_merge.py first for creating a virtual raster file (.VRT) which I used later as input file for gdalwarp. Now there seems to be a separate tool for this purpose, gdalbuildvrt. Is even seems to acceps Mapserver tileindex files as input. I guess that if you'll select to make rectangular images with no nodata areas then the work chain would include (gdaltindex) - gdalbuildvrt - gdalwarp.
-Jukka Rahkonen- Espen Isaksen wrote > Yes, that is a solution that will probably work. Do you know > the difference between gdal_merge.py and gdalwarp? > > Espen > > > > 2009/8/14 Rahkonen Jukka <[email protected]>: > > Hi, > > > > Not a very clever solution is to get rid of the collards > forever. However, it works for sure. Select a rectangular > grid in preferred output projection and mosaic and compress > the original images to suit that grid with gdalwarp by using > -te option. Then there will be no black borders to make > transparent any longer. It does not mean much extra work if > you have to compress the images in any case, but it does make > updating image layer a bit more complicated if you will > receice new images from scattered places every now and then. > > > > -Jukka Rahkonen- > > > > > >> -----Alkuperäinen viesti----- > >> Lähettäjä: [email protected] > >> [mailto:[email protected]] Puolesta Espen > >> Isaksen > >> Lähetetty: 14. elokuuta 2009 12:00 > >> Vastaanottaja: [email protected] > >> Aihe: [mapserver-users] Removing collars on raster images > >> > >> Hi! > >> > >> This question has been asked in different ways before, but the > >> threads do not seem to give me the answers I need. > >> > >> We have lots of TB of images with black collars(borders). We would > >> like to try out using Mapserver for serving these images, > but we need > >> to have the black collars transparent. > >> That is fine in Mapserver as long at you use regular Tiff. > >> However, because of the many TB of data we need to > compress this data > >> and preferably tiff with jpeg compression. > >> > >> However, this compression creates edges between the collar and the > >> image where the image does not get transparent. > >> > >> I am struggling to find a solution to this problem. Is > ideas on how > >> we can avoid this problem? Is it for example possible to set a > >> transparency mask in the Tiff image which can be used by Mapserver? > >> Another solution would be if Mapserver could support > setting an area > >> in an image transparent based on a polygon file. > >> > >> Any help is appreciated. > >> > >> Espen > >> _______________________________________________ > >> mapserver-users mailing list > >> [email protected] > >> http://lists.osgeo.org/mailman/listinfo/mapserver-users > >> > > > _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
