Optitrack camera accuracy

[dlecoutre]

Hi,

I have two Optitrack Cameras (C120 version) and one Vector Clip for head tracking. I wanted to check the accuracy of the cameras, so I placed the clip on a positioning system. This allows me to translate the clip in the x and z axis without changing any of the rotation angles. I am using the INPVector2 class to obtain the x, y, z, heading, pitch and roll values. After a little testing I have a couple of questions:

- When I use the positioning system to translate only on the X axis I see significant changes to the Heading value. For instance, I translate 100mm in either direction from 0 and I get a 5 degree change in the Heading.

- What are the units for the Z value? It does not seem to output millimeters. When I move the clip 50mm I see a 70 unit change in the Z value.

Do you have any suggestions for how to compensate for these discrepancies? I can simply multiply the Z value by 0.71 to convert it to mm, but I would like to know if there is a better way?

Thanks,

[Birch]

Please see the following thread on the same topic :
http://forum.naturalpoint.com/forum/ubb ... mber=29982

[dlecoutre]

Thanks for the link, I'd implement the INPVector3 in my .dll, if someone get this issue, just add theses lines in the initialization function :
VariantInit(&FocalLenght);
FocalLenght.vt= VT_R8;
FocalLenght.dblVal=2.6;
pVector3->put_imagerMMFocalLength(FocalLenght);

It looks like it works well now.

Thanks,