Procedure to export Dense Point Cloud/Orthomosaic to Local coordinate system

[kmfcbb]

Hello,

I have a project with photos and GCPs in WGS84, after align photos, build dense cloud, I try to set the local coordinate system (from .prj file) in Reference Settings, and then build DEM and orthomosaic, and export orthomosaic (TIFF). However, I can't get the output with a correct position.

I wonder what is the correct procedure to convert the products (point cloud and orthomosaic) to local coordinate system?

Attached is the .prj file I used, and the system prompts "unsupported datum transformation".

Thanks for suggestion.
 
Kmfcbb

[Alexey Pasumansky]

Hello Kmfcbb,

You either need to georeference the chunk in the required system, thus building the DEM and orthomosaic in the same coordinate system, or select the desired coordinate system in the export dialog, providing that both source and output systems have TOWGS84 sections defined.

[kmfcbb]

Thanks Alexey,

For the second option, you mean I do not need to change the reference settings (keep it as wgs84) before building DEM and orthomosaic? Just select the desired coordinate system when export?

However, what do you mean by providing that both source and output systems have TOWGS84 sections defined.

Besides, is there any other problem with my .prj file? Thanks

Thanks for help
Kmfcbb

[SAV]

Hi Kmfcbb,

Yes, you don't need to change your coordinate reference system (CRS) in PhotoScan (keep it as WGS84); simply choose the one you want during export.

All the best.

Regards,
SAV

[kmfcbb]

Thanks, I've got the correct way to proceed the transformation (export), and the system doesn't prompt "unsupported datum transformation" anymore.

However, the position is still not correct, there is a shift of about 70m in the NE direction. The 7 parameters in the TOWGS84 section is from a Bursa-wolf 7p model.