User's Manual

Document MV0319P.N

MVN User Manual

12.1.2 Output filtering: LXsolver

The MVN fusion engine allows some laxity between joints to allow for small errors due to for example

soft tissue movement. In the FBX export file, the positions and orientations of all segments as captured

are exported. In BVH, only the position of the root (pelvis) is exported. The other segments are rigged,

based on Euler angles with respect to the previous segment. Since the captured position of the foot can

be different than the rigged position, it can result in foot slide.

The LXsolver exports the data to a form that minimizes soft tissue artefacts and joint laxity while keeping

the feet at place. By default it is active on FBX and BVH and performed after the smoother.

Figure 55: Comparison of MVN results with and without LXsolver

12.2 BVH

The name BVH stands for BioVision Hierarchical data, and embeds captured motion data in ASCII

format which can be imported in many animation applications.

A BVH file consists of two parts, a header section which describes the hierarchy and initial pose of the

skeleton; and a data section which contains the motion data. The start of the header section begins with

the keyword ‘HIERARCHY’. The following line starts with the keyword ‘ROOT’ followed by the name of

the root segment of the hierarchy to be defined, usually the hips. Each segment contains a vector

indicating the length and direction from the parent segment. The vector is specified by the keyword

‘OFFSET’ followed by the X, Y and Z values. The ‘CHANNELS’ keyword indicates the number of

channels for this segment (usually 3 Euler angles) together with the order of rotation. On the next line,

either you will find the ‘JOINT’ keyword or the ‘End Site’ keyword. The end site information ends the

recursion and indicates that the current segment is an end effector (has no children). The end site

definition gives the length of the preceding segment just like the offset of a child defines the length and

direction of its parents segment. The world space is defined as a right handed coordinate system with

the Y axis as the world up vector.