Problem with reprojected images

[Dirk Jesko]

Dear Jukka,

thanks for the tip. I will try it. However, since there are some 250.000 
tiles, I expect problems with the performance even with pyramid layers. 
Do you have any experience with very large datasets and GDAL/VRT? 
<http://dict.leo.org/se?lp=ende&p=/Mn4k.&search=experiences>

Kind regards,
Dirk Jesko

>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: MAPSERVER-USERS at LISTS.UMN.EDU
>Aihe: Re: [UMN_MAPSERVER-USERS] Problem with reprojected images
>
>  
>