After processing several datasets we concluded that the issue is related to how Autodesk handles large .tiff files. We did not experience any issues when importing results of smaller projects (smaller orthomosaics) but, on the other hand, faced the issue while importing results of larger projects (e.g. orthomosaics of more than 500 Mb). As a consequence, the error ".tif was not found or is not valid" is displayed and the orthomosaic cannot be imported into Autodesk.
To explain further:
- The issue might also depend on the version of the Autodesk in use, for example, we were able to reproduce the issue with Autodesk Civil 3D 2019.
- We do not expect issues while importing the tiles or "smaller" orthomosaic (size of the file).
- BigTIFF is generated when tiles are merged. From our observations, the Autodesk does not know how to handle the BigTIFF and it looks as if the orthomosaic was not LZW compressed.
We suggest the following workarounds:
- Reduce the resolution of the output raster. This will substantially reduce the size of the orthomosaic and, in most cases, will have a marginal effect on visual quality.
- Load each tile of the orthomosaic one by one into Autodesk. The orthomosaic tiles are stored here ...\3_dsm_ortho_QGIS\2_mosaic\tiles. More in the Project Folder Structure article.
- Use QGIS to save the orthomosaic:
- Open QGIS.
- Drag and drop the orthomosaic generated in Pix4Dmapper.
- Right click on the corresponding layer and click Export - Save As...
- In the dialog Output mode select the Rendered image option.
- Click OK.
- Once exported, drag and drop the new orthomosaic into the main view of Autodesk.
Use IrfanView to save the orthomosaic:
- Click File > Save as...
- Save as Type: TIF
- On the TIFF save options window select LZW
- Click Save.
- Open the LZW tiff file in Autodesk.
I would like to reassure you that our team is informed about this issue but, since the issue is related to a single software (Autodesk) and does not appear in other software (e.g. IrfanView, QGIS or Global Mapper.), we are currently not considering changing the way we are saving orthomosaics.
Let us know if you have some additional information or suggestions on this topic.