Generally, GeoTIFF files containing RGB/RGBA or elevation data contain a header describing the coordinate system in which the file content data is georeferenced. For many files in a local or arbitrarily defined coordinate system, however, the GeoTIFF header does not contain the complete coordinate system definition—and may only contain a string such as "LOCAL CS." Therefore we require a supplementary definition in order to process these files correctly.
If a site has been set up with a local site calibration, it is possible to upload local GeoTIFF files for processing through the Create new dataset flow for non-PPK, or the workflow for PPK users flying DJI, Wingtra, or Quantum drones and choosing the Preprocessed data option.
In the Choose files to upload screen, tick on This file is in the site's local system for each file it applies.
Note that this option will not be shown if the selected Site does not have a local calibration.
Ticking this option tells us we should use the Site coordinate system definition (local calibration) instead of the TIFF file's header, which will likely define only the system's underlying projection (without the affine/geoid adjustments in x, y, and z).
How to know that your file is in a local system
- If you know that your file is in a system that includes a shift in X, Y, and/or Z from the underlying projection.
- If you use software that requires defining a coordinate system (such as a DC/CAL/JXL file in Trimble products or a GC3 file in Topcon products).
- More technically, if a WKT string or PRJ file cannot define the file system.
I still can't do it!
We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.
If you're stuck, you can connect with our support team by clicking the support button on the top right corner of your user portal.