Large error for the estimated yaw/pitch/roll

[Jacky Xiao]

Dear Agisoft Team,

I've meet some problem about the result of estimated rotation angle in the Reference pane .

I used a camera with IMU to take a series of pictures, so the position information (X, Y, Z) and pose information (Euler Angle) of these pictures are known, and I have verified the accuracy of these information, they are reliable. What I know now is that the rotation matrix order for this camera is yaw*pitch*roll (z-y-x axis). And the rule of the axis definition is different from the metashape one. It's:

• x axis - forward (also the picture facing)
• y axis - left
• z axis - upward

When I imported the reference, I also matched roll, pitch and yaw with those in metashape. After that, by using the function of "Align photos", I obtained very accurate results (according to the results on the right side of the software interface), the position and attitude were correct. However, when I checked the "reference Pane", It is found that the Angle has a estimated error of about 180 degrees (or worse). You may have a better understanding with the attachment.

Therefore, I would like to ask:
* What's the reason leads to this error?
* How could I solve this problem to decrease the estimated rotation angle error?

Thank you for your time and looking for your reply.

Best regards,
Jacky

[Alexey Pasumansky]

Hello Jacky,

In case you are using different convention for XYZ axis orientation, I think you should expect that camera orientation angles estimated in Metashape would not correspond to your expectations in this case.

But if you use Z-up, Y-north, X-east orientation, then you need also to check, the rotation order and direction convention defined in Metashape for yaw, pitch, roll angles, see pages 97-98 of Metashape Pro manual:
https://www.agisoft.com/pdf/metashape-pro_2_1_en.pdf
You may need to input some offset values to Camera Calibration -> GPS/IMU Offset tab for the camera orientation angles to fit the expected convention. For example, if in your case pitch=0 means that camera is looking straight forward, you need to use 90 degree offset, as pitch=0, roll=0 in Metashape means that camera is looking vertically down.

[Jacky Xiao]

Dera Alexey,

Thank you for your reply! It helps me a lot.

I would like to ask some questions about the value domain for Yaw, Pitch and Roll.

*Are they all belong to (-180, 180)?
*Does it lead to different result if I input Roll as -165° instead of 195° (plus 360°)？
*When I tick the rotation angle, the alignment result will become poor, is it because the inputed angle has large error?

I also wondering if there is a tools to help me for converting euler angle between different coordinate systems?

Thank you.

Best regards,
Jacky