Messages

1

General / Re: Red boundary box in Metashape v2.0 and sequential align question

« on: March 17, 2023, 01:14:57 PM »

I'm also experiencing the issue with the red/pink point cloud bounding box in V2.0. This seems to appears after duplicating the point cloud. The point cloud bounding box is also then visible on the original point cloud until the project is closed and opened again. I can't find a way to remove or make invisible the bounding box.

2

General / Re: Workflow to process the Photography of "PHANTOM 4 RTK"

« on: March 15, 2019, 01:52:30 AM »

Thanks Alexey, will stick with regular "in-field calibration" as you say. I have already reused this data returning good results.

3

General / Re: Workflow to process the Photography of "PHANTOM 4 RTK"

« on: March 13, 2019, 11:40:37 PM »

This is how I use the dewarp data in the XMP tags to calibrate the camera in Metashape:

Code: [Select]

<drone-dji:DewarpData> 2018-10-23;3662.110000000000,3655.160000000000,5.850000000000,-31.610000000000,-0.268279000000,0.110783000000,0.000693505000,-0.000105054000,-0.031359200000</drone-dji:DewarpData>

Date: 2018-10-23
fx: 3662.110000000000
fy: 3655.160000000000
cx: 5.850000000000
cy: -31.610000000000
k1: -0.268279000000
k2: 0.110783000000
p1: 0.000693505000
p2: -0.000105054000
k3: -0.031359200000


Where:

• fx, fy - focal length
• cx, cy - principal point coordinates
• K1, K2, K3, P1, P2 - radial distortion coefficients

As the camera calibration dialog in Metashape only supports and single value for f, I use the calibrated focal length tag from the XMP data;

<drone-dji:CalibratedFocalLength>3666.666504</drone-dji:CalibratedFocalLength>

In terms of the conversion to OSGB36 with the OSGM15 geoid inside Metashape, I've found it to do an excellent job. We recently did a survey that had to tie in with an existing traditionally surveyed area. We did use several check points surveyed using post processed solutions from a Reach RS+ then converted to OSGB36 using the OS Net online conversion tool, the resultant errors were around 2cm RMSE XY and 3cm RMSE Z. which was well within the tolerance.

Was the 2cm and 3cm RMSE from using the DJI Dewarp calibration figures and fixing them? I have just ran the same dataset with my P4R Dewarp parameters fixed in the lens calibration and get massive errors on check points ~30 and 40cm. If I allow Metashape to adjust the precalibrated values the check point accuracy is back to ~4 and 3cm RMSE. My Xmp CalibratedFocalLength is also 3666.666504 and I'm not sure this is correct as the adjusted figure that gives the lower error is very different, more like 3630.

@Agisoft Does supplying precalibrated lens data that isn't fixed get taken into account when optimising alignment, or should we just allow Metashape to optimise the lens parameters from the start?

4

General / Re: Workflow to process the Photography of "PHANTOM 4 RTK"

« on: March 09, 2019, 10:49:43 PM »

Have you verified the correctness of the transformation parameters in Photoscan/Metashape for transforming coordinates from WGS84 to OSGB1936. We've found that the parameters in Photoscan for going from WGS84 to our Dutch National CRS are incomplete and partly outdated, resulting in a couple cm of deviations in all axis. Hence we're transforming the data outside of Photoscan first before importing into it for further processing.

I have just ran the same survey without the transformation to OSGB1936, so keeping to WGS84 with GCP converted outside of Metashape and results are very close. So happy that using the OSGM15 geoid and transformation within Metashape seems to be working well, this speeds up the workflow. I have uploaded the accuracy reports to the same link before if you want to have a look.

Anyone found the best way to precalibrate the P4R lens for repeatable results?

5

General / Re: Workflow to process the Photography of "PHANTOM 4 RTK"

« on: March 07, 2019, 11:08:59 PM »

I have been doing some testing with the new P4R and getting some good results. I can't seem to enter the DJI dewarp Xmp data so that it means anything to Metashape, has anyone else yet? The auto adjusted camera parameters seem to been getting pretty good accuracy without GCP and even better just using 1 GCP.

Was flown with D-RTK2 base over known point shot with Trimble R10, lens correction turned off in RTK app. Ground control also shot with R10.

Coordinates converted to OSGB1936 in metashape before alignment and loading GCP.

I have tried to do a lens calibration with the chessboard in metashape but get very different parameters than what I see after a flight and optimisation. Anyone else been able to calibrate the P4R lens successfully with metashape?

Without running the optimisation the Z error is over 21cm but down to 6cm after. Using just one GCP tightens things up further to less than 3cm.

See reports https://drive.google.com/drive/folders/1LekTi82gf9Vq4cYkg_4s79YTnccYmgrr?usp=sharing

Let me know your thoughts.

Cheers

6

General / Re: Workflow to process the Photography of "PHANTOM 4 RTK"

« on: November 17, 2018, 11:49:51 AM »

DJI recommend to change the accuracy of the camera location to 0.1m. I have just processed your images with these setting and got these results. Just waiting for the delivery of my P4RTK. Looks promising, but would need some check points for true accuracy.

7

Bug Reports / Measure Shape Custom Level in 1.3.0 not working

« on: February 15, 2017, 11:57:45 AM »

When I try to measure a shape and select base plane to custom level, no matter what value I put in the level field and update, it always returns the volume as if the custom level field was 0m. The best fit and mean level work as they should. I don't think I am doing anything wrong as it used to work just fine in a previous version.

Can someone confirm if this is also the case for them.

Thanks