I have a GeoTIFF with internal overviews, generated using gdaladdo and the -r mode. I published this GeoTIFF in GeoServer 2.6 and I can see the image fine in map preview.

However, when I load the image in our OpenLayers 2 application, the image quality is worse. It appears as though GeoServer Map Preview is using the GeoTIFF overviews that I created using Gdal and that OpenLayers 2 is generating a new overview, using another resampling algorithm.

The layer is loaded in our app by using straight OpenLayers.Layer.WMS Is this even possible? Or am I imagining things?

2 Answers 2


It was because a difference in the app projection (EPSG:900913) and the layer registered in GeoServer (EPSG:4326). Because of that, the tiles were reprojected using the default method (nearest) and making the image look bad. I publish a new layer in GeoServer, using the correct Web Mercator projection, with overviews created using mode method and now everything looks OK.


It may well just be that your app is using a different set of zoom levels, which happen not to match so well the existing overviews

  • I'm a bit newbie in openlayers. Is ther a way to check the zoomlevels that my app is using? Can I use the scale text (eg. 1:17M) to see if the zoomlevels are the same?
    – Daniel
    Commented Nov 24, 2015 at 23:04

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