# Forum

### Author Topic: How is the roll, pitch,yaw defined?  (Read 7656 times)

#### eugenfunk

• Newbie
• Posts: 2
##### How is the roll, pitch,yaw defined?
« on: May 25, 2016, 03:26:58 PM »
Dear Agisoft team,

I would like to import a txt file in the reference pane with the full camera pose (position and orientation).
My orientation is defined in quaternions and I can convert it to any format, which can be used by Photoscan for image alignment.

I assume further, that roll, pitch, yaw are defined as euler angles. Thus, converting the quaternion to euler might be the way to go.
However, when I pass the euler angles (e.g. roll=z, pitch=x, yaw=y), (n DEG) the angle errors after the camera alignment process are very high.

* How do I map the euler angles( x,y,z) to roll, pitch, yaw assuming that my image local coordinate frame looks like this (z-front, y, down, x: right) : http://www.mathworks.com/help/vision/gs/triangulate_worldcoordinate.png

* If your roll,pitch,yaw is some sort of euler angles, is it defined as xyz or as a zyx rotation?

Thank you very much!

#### Alexey Pasumansky

• Agisoft Technical Support
• Hero Member
• Posts: 14890
##### Re: How is the roll, pitch,yaw defined?
« Reply #1 on: May 29, 2016, 07:05:57 PM »
Hello eugenfunk,

Assuming that camera is mounted under the plane looking vertically down and the direction bottom -> top on the image corresponds to the aircraft flying direction, Y axis is looking forward (flight direction), X-axis is pointing to the right wing and Z is looking to the sky (opposing to the camera pointing direction).

In this system yaw is rotation angle around Z-axis (zero means north), pitch - rotation around X-axis (zero means that nose-tail vector and wings are parallel to the ground), roll - rotation around Y-axis.
Best regards,
Alexey Pasumansky,
Agisoft LLC

#### eugenfunk

• Newbie
• Posts: 2
##### Re: How is the roll, pitch,yaw defined?
« Reply #2 on: May 30, 2016, 04:14:34 PM »
Hi Alexey,

thank you very much! However, before I can verify this in my own, I need also the rotation order.
What would it be?

Rx*Ry*Rz
or
Rz*Ry*Rx?

Thanks again!

#### Alexey Pasumansky

• Agisoft Technical Support
• Hero Member
• Posts: 14890
##### Re: How is the roll, pitch,yaw defined?
« Reply #3 on: June 02, 2016, 11:34:07 AM »
Hello eugenfunk,

PhotoScan uses the following rotation order for the Euler's angles: yaw (in negative direction, pitch and then roll.
Best regards,
Alexey Pasumansky,
Agisoft LLC