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BlackFang
Up and Coming
September 15, 2013

Reading sensor data from Oculus, Yaw doesn't go past 90

I'm able to read data from the Rift, using the oculusplugin.dll. Pitch and Roll seem to work fine. However, I turn left and yaw goes to about -90 degrees then starts to raise. I turn right, it increases to 90 degrees, then past that point starts to decrease. Any ideas what I am missing? Right now I am just calling GetOrientation(int sensor, Quat q) every tick.

Event bool GetOrientation(int sensor, Quat q)
{
	local float w, x, y, z;

    if (OVR_GetSensorOrientation(0, w, x, y, z) == true)
	{
		q.w = w; 
		q.x = x; 
		q.y = y; 
		q.z = z;	
						
		CurHMDOrientation=OrientSensor(q);
		
		return true;
	}
		
	return false;
}


EDIT: I just noticed that the Pitch seems to "flip" when the Yaw crosses -90 or 90.

    7 replies

    geekmaster
    Up and Coming
    September 15, 2013
    In this case w/x/y/z are quaternion coordinates, not Euler angle yaw/pitch/roll.

    Here is an example and discussion (which contains a minor variation of your code snippet):
    http://gmc.yoyogames.com/index.php?showtopic=591049

    Notice that 'q' is defined as a quaternion, which requires conversion to Euler angles to get roll/pitch/yaw. Your example does not do that.
    This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
    BlackFangAuthor
    Up and Coming
    September 15, 2013
    Well, between that and when I log out the data, I use a function that converts into a euler angle based rotator. (I can't log the value of quats for some reason). I've noticed that it is reading yaw as pitch, pitch as negative roll, and roll as negative yaw. I believe this is because the quat I am getting from the .dll is not using the same coordinate system. Then, as a result of the conversion, the yaw issue arises, so I can't just move and flip values post conversion. I need to reorganize the quat before conversion to angles. Do you know how I should go about rearranging the quat? I've been Googling for a few hours with nothing to show for it.

    I'm not sure what the oculus system is, but mine is x=forward, y=right, z=up.
    Edit: Oculus is Y=up, x=right, and z= backwards. Now how to change one to the other.....

    So OX=Y, OY=Z and OZ=-X. How to quatify that.....
    I complain a lot. Just think of me as a squeaky wheel lol. Youtube channel -> https://www.youtube.com/user/xblBlackFang/videos
    BlackFangAuthor
    Up and Coming
    September 16, 2013
    Somebody on stack overflow helped me. It was as simple as swapping components and flipping signs all along. I feel rather silly now :P
    I complain a lot. Just think of me as a squeaky wheel lol. Youtube channel -> https://www.youtube.com/user/xblBlackFang/videos
    MOnsDaR
    New Participant
    September 16, 2013
    Could you post the Link to your Stackoverflow Question please?
    cybereality
    Inspiring
    September 18, 2013
    Although counter-intuitive, this is actually not a bug but the way it was designed.

    If you attach an object to the orientation, you will see it appears fine, even if the angles are flipping around sometimes.
    AMD Ryzen 7 1800X | MSI X370 Titanium | G.Skill 16GB DDR4 3200 | EVGA SuperNOVA 1000 | Corsair Hydro H110i Gigabyte RX Vega 64 x2 | Samsung 960 Evo M.2 500GB | Seagate FireCuda SSHD 2TB | Phanteks ENTHOO EVOLV
    BlackFangAuthor
    Up and Coming
    October 5, 2013
    http://stackoverflow.com/questions/18818102/convert-quaternion-representing-rotation-from-one-coordinate-system-to-another
    I complain a lot. Just think of me as a squeaky wheel lol. Youtube channel -> https://www.youtube.com/user/xblBlackFang/videos
    jherico
    Inspiring
    October 5, 2013
    "BlackFang" wrote:
    http://stackoverflow.com/questions/18818102/convert-quaternion-representing-rotation-from-one-coordinate-system-to
    -another


    I ran into this issue with converting the OVR quaternion into the GLM representation.  I actually found it most intuitive to just go through Euler angles, especially since the OVR template code for fetching the angles lets you explicitly specify the axes, rotation direction and handedness:


                // Fetch the pitch roll and yaw out of the sensorFusion device
                glm::vec3 eulerAngles;
                sensorFusion.GetOrientation().GetEulerAngles<
                        OVR::Axis_X, OVR::Axis_Y, OVR::Axis_Z,
                        OVR::Rotate_CW, OVR::Handed_R
                    >(&eulerAngles.x, &eulerAngles.y, &eulerAngles.z);

                // Now convert it into a GLM quaternion.
                glm::quat orientation = glm::quat(eulerAngles);


    Just remember, the enemy's gate is 'down'.
    Brad Davis - Developer for High Fidelity Co-author of Oculus Rift in Action
    
        
                                                
    
        
    
    
    

            
    
                                        
    
            
                        
    
                                                                                                            
            

    

    

    

        
    
                    
    
    
    
    

    

    
    
    

                                        
    
                                                        
    
            
        
    
    

    

    

                                    
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