here is the link to the video (http://youtu.be/Jm46h-oCmng). The code I run in the video is ImageTargetsNative (vuforia-samples-advanced-android-4-0-103-advance) to which I add the following code snippet to print out translation vectors and a MathUtils.cpp (attached in this post) for inverse matrix calculation.
LOG("getPose CamT(%f,%f,%f)", getPoseMatrix.data, getPoseMatrix.data, getPoseMatrix.data);
QCAR::Matrix44F inverseMV = MathUtil:: Matrix44FInverse(modelViewMatrix);
LOG("inv(modelViewMatrix) CamT(%f,%f,%f)", inverseMV.data, inverseMV.data, inverseMV.data);
The phone is placed at a distance of 292mm from the marker. The video shows that translation in z direction is correct when the back-cam is used for tracking (i.e tz=290.8). When I switch to front-cam tracking, and place the phone at the same distance from the marker, the tracker returns wrong translation vector tz=382.9!
My guess is that this is caused by the error in front cam calibration matrix. The device used in the video is HTC One M8 (described in detail in previous reply).
Many thanks for your hlep.