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31 Oct 2024 19:05:00 EDT (-0400)
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From: JorgeAE
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 07:15:00
Message: <web.56d6d817a405651babd853180@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:

>
> You can always post your WIPs (Works in Progress) and SDL in the appropriate
> sections as attachments so that we can see exactly what you're trying to do and
> see where any difficult spots and hard-to-spot errors may be.
>
> Welcome to the POV-Ray forums, and good luck    :)


Thank you all for your extremely useful advice!

I have been trying out some of the ideas suggested and I am now starting with
the simplest model and will expand it to a more complex and better looking one
after gaining some more experience. I just need to get to that point, where the
basic model works :).

The "prism" function seemed to me a good way of modelling the plate, due to the
given conditions in my case (1D vibration). For the animation I chose the linear
spline curve, since I managed to make it work in other animations I tried
before.

Given this, my approach consists of assigning each of the 6 points the plate is
built up of one linear spline curve generated by the vibration data. Since I
have not yet figured out how to work properly with the array definition and
reading in, I just copied a fraction of the data points from the .txt file into
my spline curve definition. Then I defined a translating vector transformation
"vtransform" along the spline curve and assigned it to a separately declared
point of the prism. Now, this sounds so simple and yet it is not working. I am
afraid, I am committing a huge mistake or omitting a "vital" aspect regarding
the sintax :/ .

It would be awesome, if you guys take a look at my (very simple) code and give
me a hint where the error is. I can't attach anything, so I have to copy my code
in here. Thank you very much in advance!


  background{White}
  camera {
    angle 20
    location <2, 10, -30>
    look_at <0, 0, -1>
    rotate <0,40,0>
  }
  light_source { <20, 20, -20> color White }




#declare P1 = <0, -3.7 >;
#declare P2 = <0, -4.3 >;
#declare P3 = <0, -3.8 >;
#declare P4 = <0, -4.1 >;
#declare P5 = <0, -3.7 >;
#declare P6 = <0, -4.1 > ;
#declare P7 = <0, -4 >  ;
#declare P8 = <0, -3.7 > ;
#declare P9 = <0, -3.8 > ;
#declare P10 = <0, -3.9 >;
#declare P11 = <0, -3.8 >;
#declare P12 = <0, -3.8 >;
#declare P13 = <0, -3.8 >;
#declare P14 = <0, -3.7 >;
#declare P15 = <0, -4.2 >;
#declare P16 = <0, -3.6 >;
#declare P17 = <0, -3.6 >;
#declare P18 = <0, -3.9 >;
#declare P19 = <0, -4.2 >;
#declare P20 = <0, -3.7 >;
#declare P21 = <0, -3.8 >;



#declare Spline_1 =
  spline {
    linear_spline

0.00,P1,
0.05,P2,
0.10,P3,
0.15,P4,
0.20,P5,
0.25,P6,
0.30,P7,
0.35,P8,
0.40,P9,
0.45,P10,
0.50,P11,
0.55,P12,
0.60,P13,
0.65,P14,
0.70,P15,
0.75,P16,
0.80,P17,
0.85,P18,
0.90,P19,
0.95,P20,
1.00,P21,

  }// end of spline ---------------
//---------------------------------------------


   prism {
    linear_sweep
    linear_spline
    0,
    0,
    7,
    <-2,-3>,<2,-3>, <2,0>, <2,3>, <-2, 3>, <-2,0>, <-2,-3>
    pigment { Blue }
  }

  #declare A = <-2,-3,0>;
  #declare Trans1 = transform{
            translate Spline_1(clock)};
  #declare B = vtransform(A,Trans1);


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From: Bald Eagle
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 10:25:00
Message: <web.56d704f6a405651b5e7df57c0@news.povray.org>
You can always post your scene files as attachments in:

http://news.povray.org/povray.binaries.scene-files/

I tend to post atttachments in the appropriate sections first, wait until it
shows up on the message digest, and then post a link in the main discussion
thread, to make it convenient to find.

Like this:
http://news.povray.org/povray.binaries.scene-files/message/%3Cweb.56d702f78f8162b55e7df57c0%40news.povray.org%3E/#%3Cwe
b.56d702f78f8162b55e7df57c0%40news.povray.org%3E


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From: Bald Eagle
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 10:35:00
Message: <web.56d7073ca405651b5e7df57c0@news.povray.org>
Also,
An invaluable resource:

http://www.f-lohmueller.de/pov_tut/animate/pov_anie.htm
 and be aware that if you click on "Insert" in POV-Ray's menu, you can insert
huge chunks of useful pre-written code, and even add your own.


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From: Bald Eagle
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 11:10:00
Message: <web.56d70f6ea405651b5e7df57c0@news.povray.org>
Add these lines to the top of your file:

#version 3.7;
global_settings { assumed_gamma 1.0 }
#include "colors.inc"


For your prism, if you are only making a square, then you only need 5 points
instead of 7.   Your last 2 points are redundant.
 prism {
    linear_sweep
    linear_spline
    0,
    0,
    7,
    <-2,-3>,<2,-3>, <2,0>, <2,3>, <-2, 3>, <-2,0>, <-2,-3>
    pigment { Blue }
  }

If you could attach a copy of your data set, and maybe a diagram of the location
of the points on the plate, it would be easier understand the full scope, and to
head off anything that would need to be rewritten.

I'd build the "plate" as a wire mesh, using spheres as the data points, and then
maybe cylinders or sphere sweeps to connect them in a grid.
Then you could fill in the surface with triangles or smooth_triangles.

This sounds very Paul Bourke -y
Amazing stuff
http://paulbourke.net/miscellaneous/povexamples/


If you're going to make use of the clock variable, then you need to initiate
your renders with an ini file, set up for your animation.
I would suggest copying your files to a special subdirectory, since this will
generate a large collection of separate renders.

Then you need to collect all of your images into a video file so you can animate
it (or you could just use a viewer and "step" through the images one after the
other.
I use VideoMach  ( http://gromada.com/videomach/ ) for most of my work.
Other people have their preferences, based on OS, etc.
Format Factory is useful for converting to other video formats.


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From: Stephen
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 11:32:26
Message: <56d7159a$1@news.povray.org>
On 3/2/2016 4:06 PM, Bald Eagle wrote:
> If you could attach a copy of your data set, and maybe a diagram of the location
> of the points on the plate, it would be easier understand the full scope, and to
> head off anything that would need to be rewritten.

Yes, only six points. Driving me mad trying to imagine it. Are the edges 
fixed or free etc. :-)

-- 

Regards
     Stephen


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From: Bald Eagle
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 12:35:00
Message: <web.56d72336a405651b5e7df57c0@news.povray.org>
Stephen <mca### [at] aolcom> wrote:

> Yes, only six points. Driving me mad trying to imagine it. Are the edges
> fixed or free etc. :-)

That would affect things, and produce a different visual effect, yes.
I'm currently wondering if the vibrations are purely (co)sine waves and their
harmonics, or if there's some catenary in there...

Getting something smoothly interpolated might require functions and
isosurfaces...   the ball-and-stick/string grid would be pretty cumbersome,
although if you had a lot of splines that were defined using arrays... still
pretty ugly.  I haven't had that much coffee yet, and I'm not sure how much free
time I'd have to work all of that out...   :O

We're almost getting into Finite Element Method territory here.   {shivers}


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From: Bald Eagle
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 13:00:01
Message: <web.56d72995a405651b5e7df57c0@news.povray.org>
Scratch all that.
Christian Froeschlin obviously has the winning idea with the bicubic_patch.

[high five!]


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From: Bald Eagle
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 2 Mar 2016 21:45:01
Message: <web.56d7a4b7a405651b5e7df57c0@news.povray.org>
Christian,

I just got done editing a lot of code to smoothly stitch together four bicubic
patches, and what I noticed is that the surface of the patches do not coincide
with the control points - which is likely how the data set would applied -
setting the control points from the values in the file.

http://news.povray.org/povray.binaries.images/attachment/%3Cweb.56d7a3881f57d665e7df57c0%40news.povray.org%3E/4smoothbi
cubicpatches%20%5Bnumgrid%20-%20side%5D.png

Is there a way to calculate where the control point needs to be given the
surface coordinate?   I seem to recall some sort of A-Frame looking diagram,
though I'll have to go dig that up and see if there's a way to back-calculate.


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From: Stephen
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 3 Mar 2016 05:54:41
Message: <56d817f1$1@news.povray.org>
On 3/2/2016 5:30 PM, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>
>> Yes, only six points. Driving me mad trying to imagine it. Are the edges
>> fixed or free etc. :-)
>
> That would affect things, and produce a different visual effect, yes.
> I'm currently wondering if the vibrations are purely (co)sine waves and their
> harmonics, or if there's some catenary in there...
>
> Getting something smoothly interpolated might require functions and
> isosurfaces...   the ball-and-stick/string grid would be pretty cumbersome,
> although if you had a lot of splines that were defined using arrays... still
> pretty ugly.  I haven't had that much coffee yet, and I'm not sure how much free
> time I'd have to work all of that out...   :O
>
> We're almost getting into Finite Element Method territory here.   {shivers}
>
>

Damn you Moriarty! I an not going down that route. :-)

-- 

Regards
     Stephen


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From: Stephen
Subject: Re: Import of measurement data (ASCII format) in animation
Date: 3 Mar 2016 06:00:26
Message: <56d8194a$1@news.povray.org>
On 3/2/2016 5:57 PM, Bald Eagle wrote:
> Scratch all that.
> Christian Froeschlin obviously has the winning idea with the bicubic_patch.
>
> [high five!]
>
>
I don't know. I've tried it before making a water surface. As you found 
out the movement is not linear. There is also the problem with joining 
the patches together and only having six data points. Too much for my 
calcified brain. :-)

-- 

Regards
     Stephen


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