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QGIS Tips and Tricks

Fighting Pixelated Rendering

Did you ever run into QGIs displaying a GeoTIFF or another raster layer in an awful pixelated manner or did you even use the Processing ToolboxRaster toolsGenerate XYZ tiles (Directory) and got virtually unusable renderings? Here is an example of what I mean:

The first image shows what QGIs may confronts you with, the second one shows how the same data can display as well. Both renderings were generated using QGIS.

The reason for the pixelated output is not the inability of QGIS but the fact that such a smooth rendering increases the time the rendering takes and the default settings are optimized for speed. The same rendering options are also used to generate XYZ tiles so even if you usually prefer the optimization for speed you may well want to temporarily modify the options for the duration of the tile generation task. But enough ado, here's how to configure a smooth rendering:

Go to SettingsOptions… and select the Rendering tab. On this tab, locate the Rasters section and if necessary exand it. You find these settings:

Setting Value
Zoomed in resampling Neares neighbour
Zoom out resampling Neares neighbour
Oversampling 0.00

These need to be modified. There is no once choice fits it all, the optimal choice depends on what you actually want to render and on how slow a rendering you can live with but this is what I have been using for the above rendering:

Setting Value
Zoomed in resampling Cubic
Zoom out resampling Average
Oversampling 4.00

And that's it 😃

gis/qgis_tips_and_tricks.txt · Last modified: 2020/06/25 23:15 by admin