Setting QGIS Environment Variables for Performant Streaming
This is a work in progress. Please feel free to test, but use with caution!
In this tutorial, you will learn how to:
- set QGIS environment variables for performant data streaming
This tutorial describes how to setup QGIS for faster data streaming from remote resources. This tutorial has drawn heavily from the terrific work done by the TiTiler team and their dynamic tiler performance tuning guide .
This tutorial requires that you have the following tools installed on your computer:
|Software Library or Application||Version Used|
First, launch QGIS and open Settings -> Options dialog.
Next select System on the left side of the Options dialog. Scroll to the Environment section. To add an environment variable, click the large green plus sign. For each, variable added, set the Apply to Overwrite. The table below shows the variables to be set.
|CPL_VSIL_CURL_ALLOWED_EXTENSIONS||.tif,.TIF,.tiff||Attempt to read only TIF files remotely using VSI. This limits the scanning done by QGIS for other file types.|
|GDAL_CACHEMAX||200||Sets the cache for GDAL to be 200MB. (Optionally increase the size further).|
|CPL_VSIL_CURL_CACHE_SIZE||200000000||Sets the VSI cache to be 200MB. (Optionally increase the size further).|
|GDAL_DISABLE_READDIR_ON_OPEN||EMPTY_DIR||Very important to reduce the number of get requests on the remote resources.|
|GDAL_HTTP_MERGE_CONSECUTIVE_RANGES||YES||Tells GDAL to merge consecutive GET requests.|
|GDAL_HTTP_MULTIPLEX||YES||Improved performance if files are proxied through cloudfront.|
|GDAL_HTTP_VERSION||2||Improved performance if files are proxied through cloudfront.|
|VSI_CACHE||TRUE||Enable VSI caching|
|VSI_CACHE_SIZE||5000000||Increase the VSI cache size|
Once each of these environment variables has been added, restart QGIS.
That’s it! Your QGIS application is now setup for more efficient use of remote resources. If you have questions or comments consider chatting below.
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