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I have a Sentinel-2 image published on my GeoServer.

When I preview the layer, I can see it changes coloring somehow as I zoom in / out.

You can see examples in images below (look at the scale values at image bottom).

This may be not a problem at all if I'm using a "flat" 2D map like OpenLayers, but in Cesium the result is very ugly because Cesium request tiles at different zomm level due to its globe representation. See last image.

What I need to do to avoid this if it is possible?

This is how GDAL generate the image:

gdalbuildvrt -separate "myfile.vrt" B12_20m.jp2 B8A_20m.jp2 B04_10m.jp2
gdal_translate -co BIGTIFF=YES "myfile.vrt" "myfile-t.tif"
gdalwarp -t_srs EPSG:4326 "myfile-t.tif" "myfile-final.tif"

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2 Answers 2

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GeoServer by default will apply a histogram stretch to your map, if you don't want that you should specify a specific color ramp to apply to all tiles, there is a full reference here.

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The solution was to tile the image with gdal2tiles.py.

As the Sentinel-2 have about 10 meters/pixel, a level 14 pyramid was enought without loose resolution ( it's not like that... see below ).

The tif images I would go to publish in GeoServer have about 346M each.

The pyramid tile folder have a total of 130M. I think with GeoServer I would have both cost size because the GeoWebCache would create the tile pyramid anyway.

Seems good but...

I have to downgrade the image with gdal_translate -ot Byte -scale because gdal2tiles.py complains about the data size (float32).

Well...I heard some place that GeoServer will make 8bits tiles anyway (don't know).

The end result is very satisfactory and I finally have a homogeneous image at any zoom level with a acceptable resolution. WITHOUT GEOSERVER. Cesium can deal with TMS/XYZ directly. All I need is a simple http server.

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