[gdal-dev] Empty region after projecting GeoTIFF from 4326 to 102113

[Frank Warmerdam]

Jason,

gdalwarp uses a sampling technique to figure out the region of the
source image needed to produce each tile of the output image and this
works poorly for transformation "interruptions" like datelines.

Some warp options which have an effect are documented at:

  http://www.gdal.org/structGDALWarpOptions.html#a0ed77f9917bb96c7a9aabd73d4d06e08

(linked from the gdalwarp utility docs).

I think you need something like:

gdalwarp -wo SOURCE_EXTRA=100 ...

This means, for whatever imagery chunk the system thinks it needs, add
100 pixels around it.

Adding SAMPLE_STEPS to a largish value would also help but unless it
is really huge you will still likely miss a wee bit of imagery.

Best regards,
Frank

On Thu, Mar 7, 2013 at 2:11 PM, Jason Greenlaw - NOAA Affiliate
<jason.greenlaw at noaa.gov> wrote:
> I have an RGBA GeoTIFF in EPSG:4326 with an extent that wraps the 180
> decimal degree international dateline (western extent: 74.2 dd, eastern
> extent: 433.8 dd).
>
> When I attempt to project this image to either EPSG:102113 (as defined in
> $GDAL_DATA/esri_extra.wkt) or a very similar custom mercator projection, it
> results in a large empty region at the seam of the original raster (around
> 74 degrees east).  The projected result looks fine other than this empty
> area (it normalizes the image so that its origin is at the dateline, which
> is good).
>
> Although a small seam is expected since there is no data from 73.8E to
> 74.2E, the missing region is much larger than anticipated.
>
> Does anyone have any insight into why this is occurring or how to rectify
> it?
>
> The command I am using to perform the reprojection is:
>
>     gdalwarp -s_srs EPSG:4326 -t_srs EPSG:102113 -r bilinear -co
> COMPRESS=LZW -co TILED=yes rtofs-gcs.tif rtofs-102113.tif
>
> The original EPSG:4326 GeoTIFF and world file can be found at:
>
> http://jgreenlaw.org/gdal/rtofs-gcs.tif
> http://jgreenlaw.org/gdal/rtofs-gcs.wld
>
> The reprojected EPSG:102113 GeoTIFF can be found at:
>
> http://jgreenlaw.org/gdal/rtofs-102113.tif
>
> Thanks
> Jason
>
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