Reprojection Error RMS

[last6]

Hi,
I’m new to photogrammetry and looking for a little advice please.
Does anyone know how to get the Reprojection Error RMS below 1? I’ve processed multiple ortho and 3d maps and all come back with a Reprojection Error RMS of over 1. My Georeferencing RMSE is 0.01 consistently.
Flight missions are carried out through DJI Pilot 2 and missions are processed through DJI Terra. Is there something I could be doing wrong when setting up the processing?
Thanks

 

[chris-quadwinds]

New here too.

Checking a report on an ortho model I ran, mine reports an RMS of 0.871 px and an RMSE of 1.193 m. I am not using RTK base station for the mapping.

I ran the mission in Pilot 2 on the ALT setting, which caused other problems so I'll be re-running the mission using AGL with the elevation file loaded (The property had a tree covered hill on one border which resulted in about half the images being discarded during rendering).

I had an 80% overlap, auto focus settings.

The only DJI Terra parameter I tinkered with was the Distance to ground setting which defaults to 100m. For my mission I upped that to 150 (naively hoping I would correct for using ALT mode.. it did not). Maybe try altering that based on your flight elevation?

I experimented with lowering and raising that value. Lowering caused more images to be discarded, 100m and up kept the same amount of images, discarding the ones where the drone was too low above the hilly side of the property.

 

[last6]

Thanks.
I will try that. Will also try autofocus instead of Manual.

 

[jaja6009]

New here too.

Checking a report on an ortho model I ran, mine reports an RMS of 0.871 px and an RMSE of 1.193 m. I am not using RTK base station for the mapping.

I ran the mission in Pilot 2 on the ALT setting, which caused other problems so I'll be re-running the mission using AGL with the elevation file loaded (The property had a tree covered hill on one border which resulted in about half the images being discarded during rendering).

I had an 80% overlap, auto focus settings.

The only DJI Terra parameter I tinkered with was the Distance to ground setting which defaults to 100m. For my mission I upped that to 150 (naively hoping I would correct for using ALT mode.. it did not). Maybe try altering that based on your flight elevation?

I experimented with lowering and raising that value. Lowering caused more images to be discarded, 100m and up kept the same amount of images, discarding the ones where the drone was too low above the hilly side of the property.

Did you have Control Points laid and used as check points?

 

[chris-quadwinds]

Did you have Control Points laid and used as check points?

I did not manually set any. I had a kml boundary file and the Pilot 2 software planned the mission. From what I see in pilot 2 it seems to have some additional center passes it adds at the end of the flight.

My main mistake was using ALT mode and I took off from one of the lowest points on the property.

Is there a way to confirm or manually add the control points?

 

[jaja6009]

I did not manually set any. I had a kml boundary file and the Pilot 2 software planned the mission. From what I see in pilot 2 it seems to have some additional center passes it adds at the end of the flight.

My main mistake was using ALT mode and I took off from one of the lowest points on the property.

Is there a way to confirm or manually add the control points?

On the control point issue you can always go back and collect some on places that can not move such as man hole covers, paint line corners and the like.

Disregard your Coordinate accuracy RMSE if you did not use control points. Control points used as check points are the valid way to obtain your absolute accuracy.
If you have access to high end LiDAR data you could overlay your point cloud on top and use Cloud Compare to assess for accuracy, but the correct, best practice way is to collect check points with a GNSS rover in FIX.

If you flew a single grid mission with Altitude Optimization, the flight will add a single diagonal flight line from the outside of the area to the middle to collect oblique images. These oblique images will help the software correctly calibrate the cameras. If not used with nadir only images, you will have an altitude shift. of the data. But if you are not using RTK or control points you will most likely not even notice the incorrect elevations since there will be other errors in X,Y and Z due to the Single solution obtained.

 

[last6]

All great info. Thanks so much. Lots to think about.