[Qgis-user] Raster dynamic clipping mask
Andreas Neumann
a.neumann at carto.net
Tue Jun 27 12:00:47 PDT 2017
Hi Olivier,
Geotiff allows to have an alpha channel. You can create an alpha channel
from a vector layer, using gdalwarp.
Here is one of the commands I use:
gdalwarp -of GTiff --config GDAL_TIFF_INTERNAL_MASK YES -wm 500 --config
GDAL_CACHEMAX 500 -multi -wo NUM_THREADS=4 -wo OPTIMIZE_SIZE=TRUE
-cutline dop2016_lv95_cutline.gpkg -crop_to_cutline -dstalpha -co
"BIGTIFF=YES" -co "TILED=YES" -co "COMPRESS=JPEG" -co "JPEG_QUALITY=85"
-co "PHOTOMETRIC=RGB" -co "SPARSE_OK=TRUE" dop2016_lv95_tmp.tif
dop2016_lv95.tif
note the parameters "-cutline vectorfile" -crop_to_cutline and -dstalpha
I know, it is not as easy and straight-forward as you may want it to be,
but it works. And of course it is not dynamic.
Andreas
On 27.06.2017 18:26, Olivier Dalang wrote:
> Dear List,
>
> I was wondering whether there is an easy solution to have dynamic
> clipping masks for rasters, just like vector masks in Photoshop (or
> similar software) ?
>
> For now, I was using a layer with the inverted polygon renderer to
> hide with a white layer everything that is outside of the polygon.
> This works great, but then it's not possible to show anything behind
> the raster.
>
> I know it's easy to statically clip a raster, but this is not usable
> when working with some rasters types (eg. xyz tiles). Also it's not
> optimal, as the hidden area is still rendered. And it requires to
> write a copy of the layer, which can be slow and/or use a lot of disk
> space.
>
> Thanks !!
>
> Olivier
>
>
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