[x3d-public] Units for BVH vs HAnimMotion.values

[Joe D Williams]

> Apparently BVH uses degrees for rotations. 

It is not specified. There is no spec. Degrees do not appear in any x3d user code, or any where else except these too simple to use directly random examples in random bvh archives, or defult spitout of some glorified animation tool. char. Literally any animation tool worth having does not do them in terms of degrees, junk coding. If tool cannot export quaternions or axis-angle it is not worth using. And just because the helpdesk doesn't know about it doesn't mean they don't have it.

The conversion from typical bvh to axis-angle is in Part 2.
Just do the conversion and don't worry about using angles anymore. There is no standard way to interpolate angles, and for good reason. 

A bvh file is NOT x3d user code, it is just a partially documented importation that may be adapted for use with x3d HAnim. This is true no matter if it comes from some instructor-student archive somewhere on the web, or hot off the press to represent some current character animation tool generated keyframes. Even if pretty-printed with x3d it is not x3d. 

Just convert the stuff and apply to skeleton. Don't deal with the angles bs except to convert it to x3d interpolators. It is just an import format, not standard, and not x3d. 

Just convert for most fun,
Joe




-----Original Message-----
From: GPU Group <gpugroup at gmail.com>
Sent: Oct 13, 2023 12:48 PM
To: John Carlson <yottzumm at gmail.com>
Cc: X3D Graphics public mailing list <x3d-public at web3d.org>
Subject: Re: [x3d-public] Units for BVH vs HAnimMotion.values

I have the same question and posted it on h-anim. Might help to have some options and analysis of the options.1. Units statement 
Analysis: that would apply to all rotations in the file, including other scenery Transform rotations which is awkward for most workflows
2. Motion.values in radians by default
Analysis: will break some scene example data such as HAnim Annex D Motion.values which is in degrees
- would need to update Annex D
3. Motion.values in radians by default, and browsers can support degrees with a field 
Motion {
SFString [] angleUnits 'RADIANS' ['RADIANS', 'DEGREES']
//or
SFBool [] angleUnitsDegrees FALSE
}
Analysis: would still break the Annex D example which doesn't show any Motion field for angle units, and would need to update the specification for Motion to include an additional field.
4. export in degrees, and put an export option on the export option panel for Motion data in [degrees, radians] so browsers will still work either way until a more permanent solution such as 2 or 3.
Q. how many web3d browsers have implemented HAnimMotion and angle units did you use for Motion.values ?
-Doug


On Fri, Oct 13, 2023 at 12:44 PM John Carlson <yottzumm at gmail.com (mailto:yottzumm at gmail.com)> wrote:
Apparently BVH uses degrees for rotations.  Units for HAnimMotion should use radians unless otherwise specified in a UNIT statement, AFAIK. 
Comments?
 
Thanks!
 
John 
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