AutoCAD Contour/Topo Map from Drone

[gotgab]

New to Photoscan here. What's the best way to make a contour map in AutoCAD from drone photos using Photoscan, while using the least number of third party applications? Would this be possible without GCPs? Let's say all the hubbub in Photoscan are finished, and start from the type of file to be exported.

Thanks in advance. G

[SAV]

Hi gotgab,

Here is a detailed 'best practice UAV photogrammetry workflow' which you would need to follow to process imagery from a drone:
http://www.agisoft.com/forum/index.php?topic=7851.msg37494#msg37494

You could then also compute contour lines at a chosen interval from your DEM. All can be done within PhotoScan Pro. Contour lines can be exported as DXF file from PhotoScan Pro and then used in AutoCad. No third party applications needed 

Regarding GCPs. If you use a UAV with RTK or PPK capabilities that allows to record camera locations at cm accuracy, then you can get away without the use of any traditional ground control points. Alternatively, if you can accept a lower accuracy, a 'standard' UAV such as the ones from DJI which have meter GPS accuracy (location information is automatically saved with each image) might do the job for you. It always depends on what you are trying to do with your final product (e.g., getting accurate spatial measurements or just a rough volume estimate).

All the best.

Regards,
SAV

[gotgab]

This helped a lot. Thanks, SAV!
One more question though. I've exported both contour lines (DXF) and orthomosaic (tif) files using Photoscan and would like to overlay the contour over the ortho. Is there a way to export both together from Photoscan, or would a GIS software be needed for this?

Again,
G

[SAV]

Hi gotgab,

You'll have to export both files individually and then overlay them using a GIS software package such as QGIS (free, open source).

Regards,
SAV