maur_2005 opened this issue on Feb 05, 2020 ยท 5 posts
maur_2005 posted Wed, 05 February 2020 at 8:06 AM
Hi guys, is there any way to translate the Figure body parameters (rotation & translation) from the Body to the Hip?
As I understand hip parameters are relative while body parameters are absolute, so the problem is to find the formula to translate those parameters
Could you give me some advice, please?
3dcheapskate posted Thu, 06 February 2020 at 3:34 AM
I've just been playing with a Poser flamingo, and I've realized that there's more to this than meets the eye.
I loaded the white flamingo in a particular pose and set all the x/y/z/rotations/translations of both the Body and Hip to zero. (The ball at its feet marks the world origin, and is also the centre of rotation of the flamingo Body)
I duplicated it and made it red, and set the body x/y/z translations to 10/20/30 respectively and body x/y/z rotations to 30/60/90 respectively.
I duplicated the white flamingo again and made it green. For this one I set Hip x/y/z translations to 10/20/30 respectively and Hip x/y/z rotations to 30/60/90 respectively.
I had expected both flamingos (red and green) to be in the exact same location and orientation, which was obviously not true.
I duplicated the white flamingo again, made it blue, and turned off IK., and set the 6 parameters as per the green flamingo, i.e. Hip x/y/z translations to 10/20/30 respectively and Hip x/y/z rotations to 30/60/90 respectively.
The difference between the blue and green ones is simply due to IK, because there's an IK chain between the hip and feet - any rotation/translation of the hip with IK turned on (the green flamingo) will bend/stretch the legs.
The difference between the red and blue flamingos had me puzzled, but I think it's due to different rotation ordersfor the Body (yxz) and Hip (zyx)
The centre of rotation for the Hip is shown by the green crosshairs below
So you need to consider all of this
The 3Dcheapskate* occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.
*also available in ShareCG, DAZ, and HiveWire3D flavours (the DeviantArt and CGBytes flavour have been discontinued).
3dcheapskate posted Thu, 06 February 2020 at 3:50 AM
Correction: The different orientations between the red and blue flamingos had me puzzled, but I think it's due to different rotation orders for the Body (yxz) and Hip (zyx). Plus the fact that the green crosshairs of the Hip joint centre in the previous post are tilted with respect to the world axes will also have an effect.
The 3Dcheapskate* occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.
*also available in ShareCG, DAZ, and HiveWire3D flavours (the DeviantArt and CGBytes flavour have been discontinued).
adp001 posted Thu, 06 February 2020 at 4:15 AM
User @Allstereo has written anything about Posers coordinate system (and how to use it) in some Tutorials. Worth to read!
https://www.renderosity.com/?uid=Allstereo
Tutorials under Freestuff: https://www.renderosity.com/mod/freestuff/?uid=651369
maur_2005 posted Thu, 06 February 2020 at 8:15 AM
Thanks, I think I finally solved it, all it's about changing the coordinate system from relative values to absolute values by changing the matrix base