Hi, everyone.

I am working on two main projects using POVRAY and wonder as to those who
would be interested in them. As an electronics hobbisits I have started to
create several 3D components and hope to create a large library of them.
The second, of which I have already almost completed, is a fully
articulated mannequin, ideal for animations or just still poses. I would
appreciate comments, help or suggestions for either project, thank you.

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"JS" <bos### [at] yahoocouk> schreef in bericht 
news:web.45510e80be2c255be841240@news.povray.org...
> Hi, everyone.
>
> I am working on two main projects using POVRAY and wonder as to those who
> would be interested in them. [...]
> The second, of which I have already almost completed, is a fully
> articulated mannequin, ideal for animations or just still poses. I would
> appreciate comments, help or suggestions for either project, thank you.
>
Years ago, I built a couple of them myself (male + female) in Moray, using 
inverse kinematics for posing the mannequin. They are very useful in Moray 
for building scenes or just for the fun of it. However, they are not very 
efficient when used directly in POV-Ray because of the scene file structure 
generated by Moray.
I am curious about how you make posing easy and efficient in POV-Ray.

Thomas

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"Thomas de Groot" <t.d### [at] internlnet> wrote:
> "JS" <bos### [at] yahoocouk> schreef in bericht
> news:web.45510e80be2c255be841240@news.povray.org...
> > Hi, everyone.
> >
> > I am working on two main projects using POVRAY and wonder as to those who
> > would be interested in them. [...]
> > The second, of which I have already almost completed, is a fully
> > articulated mannequin, ideal for animations or just still poses. I would
> > appreciate comments, help or suggestions for either project, thank you.
> >
> Years ago, I built a couple of them myself (male + female) in Moray, using
> inverse kinematics for posing the mannequin. They are very useful in Moray
> for building scenes or just for the fun of it. However, they are not very
> efficient when used directly in POV-Ray because of the scene file structure
> generated by Moray.
> I am curious about how you make posing easy and efficient in POV-Ray.
>
> Thomas

Hi, Thomas and all.

I too used inverse kinematics to make it easy to pose the mannequin. The
method I use in POVRAY involves simple rotation about the joints. For
example, if you wanted to move the arm you would rotate the upperarm about
the shoulder and the forearm and hand would move accordingly, of which also
have their own rotation (i.e. about the elbow and wrist).

If it helps, I could post the coding for POVRAY for just the arm, for
example, and I'd be interested in your comments, suggestions, etc. It's
just the matter of treating the limbs as vectors and the joints as the
endpoints of the vectors.

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JS, That sounds like foward kinimatics...  IK is like when you control the
hand position of your maniquin and your code figures out the propper angles
and positions for the upper and lower arms.
Charles

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"Charles C" <nomail@nomail> schreef in bericht 
news:web.4552c04eedb96be92f60260@news.povray.org...
> JS, That sounds like foward kinimatics...  IK is like when you control the
> hand position of your maniquin and your code figures out the propper 
> angles
> and positions for the upper and lower arms.

Not necessarily, if the different objects are nested correctly. From 
experience I learned that it is often easier to rotate the objects 
individually to get exactly what you want. Applying IK directly (on a hand 
for instance) results sometimes in unwanted response from the rest of the 
body, especially if you do that in real time like in Moray, or in Poser.

Thomas

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Hehehe ok ok ok, I withdraw the word "propper."  ;)
Charles

"Thomas de Groot" <t.d### [at] internlnet> wrote:
> "Charles C" <nomail@nomail> schreef in bericht
> news:web.4552c04eedb96be92f60260@news.povray.org...
> > JS, That sounds like foward kinimatics...  IK is like when you control the
> > hand position of your maniquin and your code figures out the propper
> > angles
> > and positions for the upper and lower arms.
>
> Not necessarily, if the different objects are nested correctly. From
> experience I learned that it is often easier to rotate the objects
> individually to get exactly what you want. Applying IK directly (on a hand
> for instance) results sometimes in unwanted response from the rest of the
> body, especially if you do that in real time like in Moray, or in Poser.
>
> Thomas

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"Charles C" <nomail@nomail> wrote:
> Hehehe ok ok ok, I withdraw the word "propper."  ;)
> Charles
>
> "Thomas de Groot" <t.d### [at] internlnet> wrote:
> > "Charles C" <nomail@nomail> schreef in bericht
> > news:web.4552c04eedb96be92f60260@news.povray.org...
> > > JS, That sounds like foward kinimatics...  IK is like when you control the
> > > hand position of your maniquin and your code figures out the propper
> > > angles
> > > and positions for the upper and lower arms.
> >
> > Not necessarily, if the different objects are nested correctly. From
> > experience I learned that it is often easier to rotate the objects
> > individually to get exactly what you want. Applying IK directly (on a hand
> > for instance) results sometimes in unwanted response from the rest of the
> > body, especially if you do that in real time like in Moray, or in Poser.
> >
> > Thomas

Hi and thanks for your responses. Reading the faq it's 'illegal' to post
code for POVRAY in this group, so how about I include the code in a message
in the 'povray.text.scene-files' group? Then you can decide whether it's FK
or IK..!

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JS <bos### [at] yahoocouk> wrote:
> Reading the faq it's 'illegal' to post
> code for POVRAY in this group

  "Illegal" would mean that it's against the law of a country. Hardly.

  Also, I don't see too much problem in posting short SDL examples here.
For longer code it may be a better idea to set up a webpage and then post
a link to it.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> JS <bos### [at] yahoocouk> wrote:
> > Reading the faq it's 'illegal' to post
> > code for POVRAY in this group
>
>   "Illegal" would mean that it's against the law of a country. Hardly.
>
>   Also, I don't see too much problem in posting short SDL examples here.
> For longer code it may be a better idea to set up a webpage and then post
> a link to it.
>
> --
>                                                           - Warp

Hi and thank you. Here is the coding in skeleton form for an arm:

#include "colors.inc"

camera {location <0,0,-6> look_at <0,0,0>}
light_source {<0,0,-20> color White}
background {color Blue}

#declare upparm_l=<0,-1.7,0>;       //Upperarm length
#declare forarm_l=<0,-2,0>;         //Forearm length

#declare shoulder=sphere {<0,0,0>,0.4 pigment {color Red} finish {phong 1}}
#declare upparm=cylinder {<0,0,0>,upparm_l,0.3 pigment {color Yellow} finish
{phong 1}}
#declare elbow=sphere {<0,0,0>,0.35 pigment {color Green} finish {phong 1}}
#declare forarm=cone {<0,0,0>,0.3,forarm_l,0.25 pigment {color Yellow}
finish {phong 1}}
#declare wrist=sphere {<0,0,0>,0.3 pigment {color White} finish {phong 1}}
#declare hand=sphere {<0,0,0>,0.5 scale <1,1.5,1> pigment {color Orange}
finish {phong 1} translate y*-0.7}

#declare upparm_r=<0,0,0>;          //Upperarm rotation (about shoulder)
#declare forarm_r=<0,0,0>;          //Forearm rotation (about elbow)
#declare hand_r=<0,0,0>;            //Hand rotation (about wrist)

union {
    object {shoulder}
    object {upparm rotate upparm_r}
    object {elbow translate upparm_l rotate upparm_r}
    object {forarm rotate forarm_r translate upparm_l rotate upparm_r}
    object {wrist translate forarm_l rotate forarm_r translate upparm_l
rotate upparm_r}
    object {hand rotate hand_r translate forarm_l rotate forarm_r translate
upparm_l rotate upparm_r}

    translate y*2.5
}

What do you think? Just change the rotation values (upparm_r, forarm_r, and
hand_r) and everything moves accordingly. Is this inverse or forward
kinematics, or have I got the whole idea wrong? Oh, and please excuse my
bad coding but I prefer to get something working first and then worry about
whether it's badly written or not.

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"JS" <bos### [at] yahoocouk> schreef in bericht 
news:web.4553c4b2edb96be9b84243450@news.povray.org...
> What do you think? Just change the rotation values (upparm_r, forarm_r, 
> and
> hand_r) and everything moves accordingly. Is this inverse or forward
> kinematics, or have I got the whole idea wrong? Oh, and please excuse my
> bad coding but I prefer to get something working first and then worry 
> about
> whether it's badly written or not.
>

Well... I think it is forward kinematics, as transmission of rotation starts 
at the shoulder and ends at the hand. It works ok by the way.
I shall post in p.b.scene-files your scene code and my own from the right 
arm, as it is generated by Moray. Be aware that in Moray, the z-axis is 
up!!! At the end, I transformed the arm to POV-Ray coordinates. You will see 
that rotations start at the wrist and work up to the shoulder.

Hope this helps!!

Thomas

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