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From: Bald Eagle
Subject: Mesh leg bones
Date: 6 Aug 2013 21:35:01
Message: <web.5201a355ba23818d45338b700@news.povray.org>
Finally got it to work after trying / using about 5 different programs and
converting stl to obj to pov.

Coordinate system is wonky due to the right -x

Now I need to learn something about torsional force, modeling fractures, and
find a way to quicken the parsing time for the render, since I plan on doing
some animation.

I probably have to find a halfway decent way to model some simple musculature as
well.

Thanks again to everyone for their valuable suggestions (and patience) :)


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From: Le Forgeron
Subject: Re: Mesh leg bones
Date: 7 Aug 2013 01:33:32
Message: <5201dc2c$1@news.povray.org>
Le 07/08/2013 03:31, Bald Eagle a écrit :
> Finally got it to work after trying / using about 5 different programs and
> converting stl to obj to pov.
> 
> Coordinate system is wonky due to the right -x
> 
> Now I need to learn something about torsional force, modeling fractures, and
> find a way to quicken the parsing time for the render, since I plan on doing
> some animation.

The knee, you had to choose the knee ! One of the most complex joint of
the body (at least for human). Why, oh why !

On the light note, it seems that's not a human leg.

Sinews and ligaments should give you the base for muscular location.


-- 
Just because nobody complains does not mean all parachutes are perfect.


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From: MichaelJF
Subject: Re: Mesh leg bones
Date: 7 Aug 2013 14:05:01
Message: <web.52028b48975c0a2f228c53c40@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> Finally got it to work after trying / using about 5 different programs and
> converting stl to obj to pov.

That is the price to pay, if you want use only free software, but one get
accustomed to that. I think most things here can be done within Blender alone,
but I'm not familiar enough with Blender since it is really hard to learn.

>
> Coordinate system is wonky due to the right -x
>
> Now I need to learn something about torsional force, modeling fractures, and
> find a way to quicken the parsing time for the render, since I plan on doing
> some animation.

What have in your mind? Fractures are as indivual as the forces are causing
them. Sometimes you have a clean cut, sometimes you have a comminuted fracture.
Last ones usually are closed (no trauma to the skin), first ones have a higher
probability to be open (penetration of the skin), IIRC.

LeForgeron is completely right to propose the knee - or better a position close
to the knee. First the bones are biggest there and a "destruction" should be
easier to be modelled. I would propose the head of the tibia close to the knee.
E.g. a typical traffic accident between a pedestrian and a car will hit this
area resulting in a comminuted fracture of the tibia, not necessarily the
fibula(I had my experiences with that). IIRC (again) fractures to the patella
are very rare, since it simple gives way resulting in a luxation and not a
fracture most likely.

>
> I probably have to find a halfway decent way to model some simple musculature as
> well.

Here you are at your own I fear.

> Thanks again to everyone for their valuable suggestions (and patience) :)

You are welcome,

Best regards,
Michael


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From: Bald Eagle
Subject: Re: Mesh leg bones
Date: 7 Aug 2013 17:35:00
Message: <web.5202bd78975c0a2f45338b700@news.povray.org>
> I think most things here can be done within Blender alone,
> but I'm not familiar enough with Blender since it is really hard to learn.

Yeah.  It looks VERY powerful, but at the expense of a steep learning curve and
grappling with 10 million buttons.  :)


> What have in your mind? Fractures are as indivual as the forces are causing
> them.

Spiral fracture of the right tibia, distal to the tibial diaphysis, right mid-
to distal spiral fracture extending distally to 2-3cm proximal to growth plate,
10% posterior displacement of the distal fragment.

Medical papers suggest this is highly reproducible.

It's probably only the actual tibial fracture that needs to me modeled with any
degree of realism and precision.  The rest of the anatomy and movement are just
sort of along for the ride, to give some perspective.
I only want to _model_ musculature, not necessarily graphically illustrate it in
an artistically realistic fashion.  The idea is simply to show that while
external forces are being applied, a voluntary contraction or involuntary reflex
will cause a torsional force to the tibia as well.

Perhaps Rune, Friederich Lohmueller, Sascha Ledinsky, Christoph Hormann, Andrel,
or John VanSickle may have some positive suggestions for me.  They all appear to
have done impressive work in related areas of modeling.


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From: MichaelJF
Subject: Re: Mesh leg bones
Date: 8 Aug 2013 14:35:00
Message: <web.5203e3f2975c0a2fbe3217ba0@news.povray.org>
I think that the one or other user here will not really comprehend the medical
terminology. I for myself am not a medic but made an examn and worked as a male
nurse for some 15 years. But this is 17 years to the past now and I must admit I
have forgotten a lot. But not all;-) Now I'm a stastitician within the German
health insurances and working more in the fields of health economics and/or
epidemiology.

I think you are trying to model something like this (to have a picture to users
not familiar with medical terms):
http://149.203.233.103/storage/documents/20090221182358993/MIRCdocument.xml

I'm not quiet sure if an approach with csg operations is the best here. IMO you
should use a mesh editor to achieve your goal. E.g. after you have modeled the
fractur lines you must stamp out the medullary cavity.

Wings cannot handle csg like operations (or I'm to stupid to find them after
using it for some years, which is possible), Blender has an boolean operator
which can handle unions, differences and intersections of meshes. But I'm not
familiar with Blender enough to give you more hints. But it really seems that a
steep climb is worth the effort. I will go for it within the next months.

Best regards,
Michael


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From: Stephen
Subject: Re: Mesh leg bones
Date: 8 Aug 2013 14:47:46
Message: <5203e7d2$1@news.povray.org>
On 08/08/2013 7:31 PM, MichaelJF wrote:
> But it really seems that a
> steep climb is worth the effort. I will go for it within the next months.

Blender is a lot easier to use than it used to be. The difficulty that I 
have found is changing my mind set from mathematically based modelling 
to mesh based. The boolean operations in Blender work best with simple 
meshes. But there are other tools that can do what boolean operators do, 
such as the knife tool for cutting out shapes from a mesh.

-- 
Regards
     Stephen


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From: MichaelJF
Subject: Re: Mesh leg bones
Date: 8 Aug 2013 15:20:01
Message: <web.5203ef38975c0a2fbe3217ba0@news.povray.org>
Stephen <mca### [at] aolcom> wrote:
> On 08/08/2013 7:31 PM, MichaelJF wrote:
> > But it really seems that a
> > steep climb is worth the effort. I will go for it within the next months.
>
> Blender is a lot easier to use than it used to be. The difficulty that I
> have found is changing my mind set from mathematically based modelling
> to mesh based. The boolean operations in Blender work best with simple
> meshes. But there are other tools that can do what boolean operators do,
> such as the knife tool for cutting out shapes from a mesh.
>
> --
> Regards
>      Stephen

Yes indeed, but you need a good tutorial. There are a lot of video tut's out
there, but I hate them. Sometimes you have the impression that the author is
really capable but cannot remove the bubblegum between his teeth. Or they
speaking a slang no non natural speaker can understand. Finally I found a very
fine text book in German language which explains many things very fine but
cannot use it since my step son lend it for a while...

Best regards,
Michael


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From: Stephen
Subject: Re: Mesh leg bones
Date: 8 Aug 2013 16:05:57
Message: <5203fa25$1@news.povray.org>
On 08/08/2013 8:19 PM, MichaelJF wrote:

>
> Yes indeed, but you need a good tutorial. There are a lot of video tut's out
> there, but I hate them. Sometimes you have the impression that the author is
> really capable but cannot remove the bubblegum between his teeth. Or they
> speaking a slang no non natural speaker can understand. Finally I found a very
> fine text book in German language which explains many things very fine but
> cannot use it since my step son lend it for a while...
>

Ooo! You worry me. I promised MR a tutorial on how to install the PovRay 
add-on. I've made the video but have still to finish the audio. (It 
should be done soon.) Instead of bubblegum between my teeth it might be 
haggis. ;-) Hoots Mon.)
I found quite a few good tutorials (in English) but when I started 
Blender, this time, I had about a month to devote full time to it.

As for your step son, can you not swap him for another copy? ;-)
-- 
Regards
     Stephen


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From: LanuHum
Subject: Re: Mesh leg bones
Date: 8 Aug 2013 16:15:01
Message: <web.5203fba4975c0a2f7a3e03fe0@news.povray.org>
"MichaelJF" <mi-### [at] t-onlinede> wrote:
Blender not have current export
I have current export with users problems
Problem with official exporters: matrix
Matrix - this is calculate begin. File povray shouldn't have matrix
transformations
Developers of the exporter have no time, but started working the excessive.They
finish by 2030
In your problem it is necessary: matrix*ob.global_matrix


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From: MichaelJF
Subject: Re: Mesh leg bones
Date: 8 Aug 2013 16:50:00
Message: <web.5204045c975c0a2fbe3217ba0@news.povray.org>
"LanuHum" <Lan### [at] yandexru> wrote:
> "MichaelJF" <mi-### [at] t-onlinede> wrote:
> Blender not have current export
> I have current export with users problems
> Problem with official exporters: matrix
> Matrix - this is calculate begin. File povray shouldn't have matrix
> transformations
> Developers of the exporter have no time, but started working the excessive.They
> finish by 2030
> In your problem it is necessary: matrix*ob.global_matrix

Sorry but I'm not responsible for the POV exporter from Blender to POV. As all I
know, Maurice does this job (aka mr here). And as I posted my experiences with
Blender are limited so far.

Best regards,
Michael


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