gdalwarp with change in projection for tiles then adjacent tiles overlap slightly with a black border at edge.

[Rahkonen Jukka]

Hi,

You can mosaic all the original tiles to gdal VRT virtual mosaic in seconds by using a modified gdal_merge python script.  There are references to this in mailing list archives.  If you then use this VRT as source and give the extents you would like to have on your result image for gdalwarp (parameter TE if I remember it right just now) you will get a seamless image with one run.

Regards,

-Jukka Rahkonen-




-----Original Message-----
From: UMN MapServer Users List on behalf of David Lowther
Sent: Thu 5.4.2007 18:01
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] gdalwarp with change in projection for tiles then adjacent tiles overlap slightly with a black border at edge.
 
Not easily that I have found. 

 

One method that I have used was to calculate the overlap from adjacent
images necessary to cover the black border resulting from projection,
generate an image from the source tile and the eight adjacent tiles (not the
whole of the adjacent tiles, just the requisite margin), project, the clip
back to target projected extent.

 

However, if you can afford the disk space, creating the one large mosaic,
projecting, and then clipping out tiles is way easier.

 

David Lowther

  _____  

From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of John Mitchell
Sent: Thursday, April 05, 2007 10:41 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] gdalwarp with change in projection for tiles
then adjacent tiles overlap slightly with a black border at edge.

 

Hi,

I have found that running gdalwarp with a change in projection individually
for each tile and splitting them up via gdal_translate that the adjacent
tiles overlap slightly with a black border at edge.  If I instead run
gdalwarp against all the tiles to create a big mosaic with a change in
projection and then split(gdal_translate) them up that I don't have this
overlap. 

Is their a way to individually run gdalwarp with a change in projection
against each tile without getting this overlap?

Thanks,

-- 
John J. Mitchell