[mapserver-users] NoData Gap between rasters - Tileindex Layer

[Bartlomiej Burkot]

Hi,

Thanks Jakkua for your suggestion. I recreated the layer with the new 
options in gdalwarp:
-tr 0.36 0.36 -tap
which are nearly similar to the output raster before the test.
Additionaly I didn't create pyramid overviews with gdaladdo as I did it 
before.

The result is the same. There is still the gap between rasters in 
tileindexlayer.
http://mmapa.pl/newtestraster/big_zoom_level.PNG
http://mmapa.pl/newtestraster/extrem_line.PNG

http://mmapa.pl/newtestraster/sample_between_two_rasters.PNG
http://mmapa.pl/newtestraster/sample_between_two_rasters2.PNG

I noticed that the white line (noDataValue OR transparent area) occures 
in different places per each wms request (different extent).

I did another test:
I've created 3 layers in Mapserver:
1 - as tileindex (TILEINDEX tindex.shp)
2 - as normal one raster file raster2.tif
DATA "raster2.tif"
         TYPE RASTER
3 - as normal one raster file raster3.tif

I've requested the 3 layers in qgis:
http://mmapa.pl/newtestraster/wms_from_tileindex.PNG
http://mmapa.pl/newtestraster/two_wms_layers_with_separate_raster.PNG 
--here I opened two layers in qgis each layer was configured as separate 
raster file.
Than I opened one qgis layer as wms choosing two layers 
(LAYERS=raster2,raster3)
http://mmapa.pl/newtestraster/one_wms_request_with_two_layers_as_separate_raster.PNG

All files include this strange white line.

Than I opened the two raster files directly form qgis as rasterlayers.
http://mmapa.pl/newtestraster/two_rasters_displayed_directly_from_file.PNG
And the mapimage is correct.

I think it has something to do in resampling during rendering the image 
by mapserver.

I noticed that mapserver moved the lower raster pixels by some gap down:
http://mmapa.pl/newtestraster/gap_between_rasters_in_mapserver.PNG

By opening two rasters directly in qgis there is no shift between pixels 
of both rasters.
http://mmapa.pl/newtestraster/no_gap_between_rasters_in_qgis_opened_rasters.PNG

Do you have some more suggestions to help me?

Bartek


W dniu 2014-08-29 12:30, Rahkonen Jukka (Tike) pisze:
>
> Hi,
>
> Run gdalwarp with --tr and --tap http://www.gdal.org/gdalwarp.html. 
> Usually it helps.
>
> -Jukka Rahkonen-
>
> Bartlomiej Burkot wrote:
>
> Dear MS Users
>
> I have a set of rasters which I warped to epsg:3857 projection using 
> gdalwarp.
> During the reprojecting the new raster had been rotated by small angle.
> After that I created a tileindex shape file using gdaltindex and 
> configured layer:
> LAYER
>         NAME "myname"
>         TILEINDEX "tilindex.shp"
>         TYPE RASTER
>         OFFSITE 0 0 0
>     END
>
> On the result map I see the gaps between raster files. Please look at 
> images:
>
> http://mmapa.pl/gaps_between_rasters.PNG
> http://mmapa.pl/two_separate_files.PNG
> http://mmapa.pl/mapserver_layer_as_tileindex.PNG
>
> Maybe some of you recognize the problem. There is the problem with one 
> pixel gap between raster files in tileindex layer.
>
> Maybe there is a option in gdalwarp command to extend the new image by 
> making it 1 pixel widther? Maybe something like resampling method or 
> algorithm?
>
> I googled similar problem in goeserver:
> https://www.mail-archive.com/geoserver-users@lists.sourceforge.net/msg06220.html
>
> Could you please point me to the right solution?
>
> Thanks in advance
>
> Bartek
>

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