[GRASS-user] Create outer line of raster

GRASS GRASS user
, ,
1

Hi List,

I have an ECW-file which I convert to GeoTiff using gdal_translate.

This GTiff file I use in GeoServer as a base map.

This is working great, but because I compress the GTiff with JPEG I get white borders around my area. To solve this I can clip my GTiff with the outer line of my original ECW file.

My question is how to create such an outer line. I can of course draw it myself using QGis or MapWindow but I’d prefer to let it calculated.

Can GRASS do this? If so which command do I need.

Thanks,

Paul

2

My question is how to create such an outer line. I can of course draw it

myself using QGis or >MapWindow but I'd prefer to let it calculated.

Can GRASS do this? If so which command do I need.

(1) gdaltindex - builds a shapefile as a raster tileindex
(http://www.gdal.org/gdaltindex.html)

or

(2) g.region rast=yourrast
      v.in.region - Creates a vector polygon from the current region extent.
     (http://grass.osgeo.org/grass64/manuals/v.in.region.html)

HTH

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best regards
Helmut
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3

Hi Paul,

you could also use the original ECW-file as a mask in GRASS:

g.copy ecw_sample,MASK

and then any action you will perform for raster processing will only be within that Mask (assuming the ECW-file does not have any NULL-values inside).

Stefan

···

2013/1/9 Paul Meems [via OSGeo.org] <[hidden email]>

Hi List,

I have an ECW-file which I convert to GeoTiff using gdal_translate.

This GTiff file I use in GeoServer as a base map.

This is working great, but because I compress the GTiff with JPEG I get white borders around my area. To solve this I can clip my GTiff with the outer line of my original ECW file.

My question is how to create such an outer line. I can of course draw it myself using QGis or MapWindow but I’d prefer to let it calculated.

Can GRASS do this? If so which command do I need.

Thanks,

Paul

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