Re: [osg-users] Vicon tracking
Thanks for your answers. I understand the theory behind this, which means that I will need to set projection matrices for the left and right eye cameras according to my distance to the display surface. The problem is, can these cameras be retrieved and have their projection matrices modified before each viewer.frame() call? As I have mentioned, at the moment I am using the ---stereo command line argument to enable stereo. I read at an older thread(around July 2009) that cameras could not be retrieved using the viewer object, but this was going to change. Now I see a getCameras method in the Viewer class. Will that work for me, or will setting the camera matrices interfere with the already implemented stereo rendering? In that case, will I need to set stereo settings to off and implement stereo manually using slave cameras, as was suggested at that thread? By the way, the stereo settings wiki: http://www.openscenegraph.org/projects/osg/wiki/Support/UserGuides/StereoSettings mentions: "If the user is planning to use head tracked stereo, or a cave then it is currently recommend to set it up via a VR toolkit such as VRjuggler, in this case refer to the VR toolkits handling of stereo, and keep all the OSG's stereo specific environment variables (below) set to OFF" Does anyone know if this is still the case, or is that note outdated? Thanks a lot Mel -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=25587#25587 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Vicon tracking
Hey all, Many thanks for your answers. The Vicon system uses a z-up coordinate system, with millimeter units. It sends x,y,z coordinates for a given tracked object(in that case the cap you are wearing) as well as rotation information in axis/angle form. The client I'm using converts this to three different forms I can use interchangeably: 1. Euler angles 2. Global rotation matrix 3. Quaternion Right now I am just using the viewer->getCamera()->setViewMatrix() call before the viewer.frame() call. The problem seems to be that the matrix I pass to setViewMatrix() does not seem to be correct. I use the x,y,z coordinates for the cap to set the translation matrix ( tr.makeTranslate() ) and the quaternion to set the rotation matrix ( rot.makeRotate() ). I then multiply tr * rot and pass this to setViewMatrix(). The result is that when I move closer to the projected image, the rendered objects seems to come closer, which is correct behavior, but when i rotate my head this causes the rendered objects to rotate in the opposite direction. The code I use is from the OSG Quick start guide and it was supposed to change the view according to its description. However this does not seem to be the case for two reasons, from what I found out last night reading one old camera tutorial: 1. You have to inverse the tr*rot result first 2. After you do that, you have to rotate -90 degrees about the x-axis because Matrix classes use a Y-up coordinate frame whereas the viewer uses a Z-up coordinate frame. Will these two corrections solve the problem? Will I also need to do something more advanced like dynamically changing the frustum according to the head position? Thank you! Cheers, Mel P.S Sorry if my questions seem nub. I just thought I had the necessary background for understanding rotation and translation transformations but I'm completely confused by how OSG handles these and why it uses different coordinate frames in different situations. Anw, perhaps I'm confused by DirectX because camera manipulation was much easier with the separation of the Modelview matrix in two different matrices whereas in OpenGL you may be moving/rotating objects instead of the actual camera viewpoint. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=25121#25121 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Vicon tracking
Hey, I was wondering if anyone knows what would be the best solution for building an application where the camera is headtracked using motion captured data provided in realtime from a Vicon system in OpenSceneGraph. I can get the position and rotation of the 'real' camera (cap with infrared markers) at every frame but was not successful in using these to move the camera in OpenSceneGraph. Also I have to mention that the application is rendered in a stereo projector. Right now I'm only using the --stereo QUAD_BUFFER command line argument but I'm not sure if this is the appropriate way to do this. I apologise if this has been answered somewhere else. Any help is much appreciated. Thank you! Cheers, Mel -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=25082#25082 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
