Hi Nick

The rotations are wrt to the global ref. of the system in this case.

The RotMat will just provide a rotation matrix and it is what you

use it for which will decide if it is wrt to local or global

cooridnate systems.

So in this case where we set the Axes property of the segment it is

wrt to the global system, but if we had applied the rotation to an

ARel of an node on a segment it would be the coordinate system of

this node.

I when the lines below says:

RotMat((pi/180)*JointPos.Right.GlenohumeralFlexion ,z)*

it will rotate the segment around the global z axis

then it is mulitplied by the rotmat

RotMat((pi/180)*JointPos.Right.GlenohumeralExternalRotation ,y)

which is then effectively a rotation wrt. to already rotated syetem.

So it is only the first rotation which is wrt. to the global

coordinate system.

Best regards

SÃ¸ren, AnyBody Support

— In anyscript@yahoogroups.com, “stl_nick_gt” <nflieg@…> wrote:

>

> Hi Christian,

>

> I’m pretty sure that I understand the mechanics of the RotMat

> command, but I am unsure as to what the x,y and z axes are

referring

> to. Are they global, or the local of the humerus? In context

from

> the InitialPositions.any file:

>

> //right humerus

> ref.Right.ShoulderArm.Seg.Humerus.Axes0 =

> ref.Trunk.SegmentsThorax.ThoraxSeg.Axes0*

> ref.Trunk.SegmentsThorax.ThoraxSeg.ij.ARel*

> ref.Trunk.SegmentsThorax.ThoraxSeg.ij.RotNode.ARel*

> RotMat((pi/180)*JointPos.Right.GlenohumeralFlexion ,z)*

> RotMat((pi/180)*JointPos.Right.GlenohumeralExternalRotation ,y)*

> RotMat((pi/180)*JointPos.Right.GlenohumeralAbduction ,x)*

> ref.Right.ShoulderArm.Seg.Humerus.gh.RotNode.ARel’*

> ref.Right.ShoulderArm.Seg.Humerus.gh.ARel’;

>

> It is not immediately clear what coordinate system the x,y, and z

> are with respect to.

>

> Nick

>

> — In anyscript@yahoogroups.com, “Christian Gammelgaard”

> <cgol03@> wrote:

> >

> > Hi Nick

> >

> > the x,y and z in RotMat is refering to the axis that the first

> > argument is rotating around.

> > I am not sure I understand you correct, but the initial

positions

> is

> > the position you want the model to stand in after it is loaded.

The

> > initial position does not change during the kinematic movements.

> >

> > Best Regards Christian

> >

> > — In anyscript@yahoogroups.com, “stl_nick_gt” <nflieg@> wrote:

> > >

> > > In the “InitialPositions.any” file for StandingModel, what are

> > > the ‘x’, ‘y’, and ‘z’ in RotMat refering to? From what I can

> gather

> > > observationally, they initially refer to the global

coordinates

> (x -

> > > anterior, y - superior, z - lateral) located at the origin of

> the

> > > humerus, but then they move with the humerus through each

> rotation (so

> > > therefore order matters). Is this correct? Or are the axes

used

> > > almost the same direction as global? If this is the case, how

> do find

> > > the direction of these rotational axes?

> > >

> > > Nick

> > >

> >

>