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Am 04.12.2017 um 13:40 schrieb Thomas de Groot:
> On 4-12-2017 9:11, Thomas de Groot wrote:
>> On 3-12-2017 14:17, Bald Eagle wrote:
>>> Hey!
>>> I like the results you're getting.
>>> In fact, I like the holes in the mesh so much, that maybe you could
>>> think about
>>> exploiting that effect by randomly creating holes in the mesh to give a
>>> "spiking" effect - I think that would be an excellent Gormley-inspired
>>> methodology.
>>
>> For the time being I treat them as artefacts.
>>
>
> I don't know what those spikes represent finally. I closed the model and
> still the eyes show them, except if I increase minutely the Step
> parameter. Any idea?
My guess would be that your mesh is "closed" in a different sense than
what would constitute a "closed" mesh in the sense POV-Ray interprets it.
For instance, a human figure mesh may be comprised of (1) a surface
representing the skin, which is open at the eyes, and (2) a pair of
convex spheres representing the eyeballs.
In such a setup, no ray could travel from the "inside" of the figure's
head to the outside without encountering /at least one/ surface, which
you might consider "closed".
However, in POV-Ray's sense a mesh is only "closed" if a ray traveling
from the "inside" of the figure's head to the outside always encounters
an /odd number/ of surfaces.
This is the case if, and only if, there are no "open edges" in the mesh,
i.e. each edge joins an even number of triangles.
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On 4-12-2017 16:47, clipka wrote:
> Am 04.12.2017 um 13:40 schrieb Thomas de Groot:
>> I don't know what those spikes represent finally. I closed the model and
>> still the eyes show them, except if I increase minutely the Step
>> parameter. Any idea?
>
> My guess would be that your mesh is "closed" in a different sense than
> what would constitute a "closed" mesh in the sense POV-Ray interprets it.
>
> For instance, a human figure mesh may be comprised of (1) a surface
> representing the skin, which is open at the eyes, and (2) a pair of
> convex spheres representing the eyeballs.
>
> In such a setup, no ray could travel from the "inside" of the figure's
> head to the outside without encountering /at least one/ surface, which
> you might consider "closed".
>
> However, in POV-Ray's sense a mesh is only "closed" if a ray traveling
> from the "inside" of the figure's head to the outside always encounters
> an /odd number/ of surfaces.
>
> This is the case if, and only if, there are no "open edges" in the mesh,
> i.e. each edge joins an even number of triangles.
>
I agree about those eye orbits and balls. However, I deleted the eye
balls and closed the eye orbits. So, strictly speaking, the mesh is
completely 'closed'.
Remembering a more ancient discussion, I change the inside vector of the
mesh from the standard (Poseray-generated) <0,0,1> to <1,0,1>.
Interestingly, that generates an additional spike (see image).
--
Thomas
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Attachments:
Download 'antony gormley sim.png' (364 KB)
Preview of image 'antony gormley sim.png'
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On 4-12-2017 14:20, Bald Eagle wrote:
> Thomas de Groot <tho### [at] degroot org> wrote:
>
>
>> Finally, as first approximation, I found it more expedient to randomise
>> the points in the array when reading them.
>
> Hmmm.
> Without seeing how you're going about that, I'm not sure I understand the
> advantage of that over selecting a (pseudo)random point in an ordered array.
>
> I do think that one thing that could be done is add a bit of randomization to
> the point itself - since they are all regularly spaced in a cubic grid.
> ("cubic" is just easier to say/write than "rectangular solid")
>
> So, perhaps define half the grid spacing as a multiplier (M), and randomly
> translate along x, y, and z by rand_between (-M and M).
> Add a rotation if you're using an asymmetric filler.
>
> Or draw a cylinder between the original point and a randomly translated or
> chosen outside point.
>
>
> It's certainly looking more evenly filled - which I think is what you wanted.
>
Sorry, indeed. I use the following code:
union {
#while (defined(ObjLocs))
#read (ObjLocs, Locs)
sphere {0, 0.01
#local Locs = Locs*RRand(0.99, 1.01, Stream0);
translate Locs
pigment {Red}
}
#end
rotate 20*y
}
As you can have noticed from my answer to Clipka, I am really puzzled by
the 'spikes'...
--
Thomas
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Incidentally, replacing:
#declare MinZ = floor(Min.z);
#declare MinY = floor(Min.y);
#declare MinX = floor(Min.x);
#declare MaxZ = ceil(Max.z);
#declare MaxY = ceil(Max.y);
#declare MaxX = ceil(Max.x);
by:
#declare MinZ = Min.z;
#declare MinY = Min.y;
#declare MinX = Min.x;
#declare MaxZ = Max.z;
#declare MaxY = Max.y;
#declare MaxX = Max.x;
speeds up the parsing manifold. From a couple of minutes (Steps=0.01;)
to a couple of seconds. Results are identical though it may generate
problems of course where the the limit and the object are identical.
--
Thomas
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On 4-12-2017 16:47, clipka wrote:
> My guess would be that your mesh is "closed" in a different sense than
> what would constitute a "closed" mesh in the sense POV-Ray interprets it.
>
Problem SOLVED (I guess).
To close the mesh, I left a number of quadrangular new surfaces. I
re-triangulated the model and the spikes disappeared. No entirely sure
/why/ this happened though; I do not remember having met this before.
--
Thomas
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Thomas de Groot <tho### [at] degrootorg> wrote:
> Incidentally, replacing:
>
> #declare MinZ = floor(Min.z);
> #declare MinY = floor(Min.y);
> #declare MinX = floor(Min.x);
> #declare MaxZ = ceil(Max.z);
> #declare MaxY = ceil(Max.y);
> #declare MaxX = ceil(Max.x);
>
> by:
>
> #declare MinZ = Min.z;
> #declare MinY = Min.y;
> #declare MinX = Min.x;
> #declare MaxZ = Max.z;
> #declare MaxY = Max.y;
> #declare MaxX = Max.x;
>
> speeds up the parsing manifold. From a couple of minutes (Steps=0.01;)
> to a couple of seconds. Results are identical though it may generate
> problems of course where the the limit and the object are identical.
>
> --
> Thomas
That's HIGHLY unexpected, since it's only 6 rounding directives.
I only did that to give integers for referencing array items.
It's not like any of that gets looped... :O
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On 5-12-2017 13:35, Bald Eagle wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Incidentally, replacing:
>>
>> #declare MinZ = floor(Min.z);
>> #declare MinY = floor(Min.y);
>> #declare MinX = floor(Min.x);
>> #declare MaxZ = ceil(Max.z);
>> #declare MaxY = ceil(Max.y);
>> #declare MaxX = ceil(Max.x);
>>
>> by:
>>
>> #declare MinZ = Min.z;
>> #declare MinY = Min.y;
>> #declare MinX = Min.x;
>> #declare MaxZ = Max.z;
>> #declare MaxY = Max.y;
>> #declare MaxX = Max.x;
>>
>> speeds up the parsing manifold. From a couple of minutes (Steps=0.01;)
>> to a couple of seconds. Results are identical though it may generate
>> problems of course where the the limit and the object are identical.
>>
>> --
>> Thomas
>
> That's HIGHLY unexpected, since it's only 6 rounding directives.
> I only did that to give integers for referencing array items.
>
> It's not like any of that gets looped... :O
>
Yes, I did not expect that at all either. I am baffled.
--
Thomas
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Thomas de Groot <tho### [at] degrootorg> wrote:
> >> Finally, as first approximation, I found it more expedient to randomise
> >> the points in the array when reading them.
Ah. I understand now.
"I found it more expedient to add a random translation to the point values
before storing them in the array, as they are read in from the file."
(I will admit, it's one of those things that's a bit hard to phrase before 2nd
coffee.. I'm likely further challenged by the damage that American compulsory
public education caused me.)
I think it's something that would save the time of one addition per point if the
number of points to be plotted exceeded the number of entries in the array, and
it would prevent overlap of objects slightly differing in position for the same
array entry.
http://izquotes.com/quotes-pictures/quote-schools-were-designed-by-horace-mann-and-barnard-sears-and-harper-of-the-univ
ersity-of-chicago-and-john-gatto-343105.jpg
https://i.pinimg.com/736x/57/14/a2/5714a25f482e091f882ffc1a52fed042--compulsory-education-education-system.jpg
https://i.pinimg.com/736x/c5/9f/3f/c59f3f93df48042001f325789ac42439--public-school-quotations.jpg
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On 5-12-2017 13:52, Bald Eagle wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>
>>>> Finally, as first approximation, I found it more expedient to randomise
>>>> the points in the array when reading them.
>
> Ah. I understand now.
>
> "I found it more expedient to add a random translation to the point values
> before storing them in the array, as they are read in from the file."
>
> (I will admit, it's one of those things that's a bit hard to phrase before 2nd
> coffee.. I'm likely further challenged by the damage that American compulsory
> public education caused me.)
LOL. Not being a native speaker, I have a hard time to formulate them in
such a way that it may puzzle you... ;-)
Stephen is much better at it than I am... :-)
>
> I think it's something that would save the time of one addition per point if the
> number of points to be plotted exceeded the number of entries in the array, and
> it would prevent overlap of objects slightly differing in position for the same
> array entry.
Still something I am not sure about, but I shall try.
>
>
>
>
>
>
>
http://izquotes.com/quotes-pictures/quote-schools-were-designed-by-horace-mann-and-barnard-sears-and-harper-of-the-univ
> ersity-of-chicago-and-john-gatto-343105.jpg
>
https://i.pinimg.com/736x/57/14/a2/5714a25f482e091f882ffc1a52fed042--compulsory-education-education-system.jpg
>
https://i.pinimg.com/736x/c5/9f/3f/c59f3f93df48042001f325789ac42439--public-school-quotations.jpg
>
>
I am not familiar with American school education systems, but from my
own experience in Europe, I disagree on most points and provide marginal
notes for the others. ;-)
--
Thomas
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On 06/12/2017 08:03, Thomas de Groot wrote:
> On 5-12-2017 13:52, Bald Eagle wrote:
>> Thomas de Groot <tho### [at] degrootorg> wrote:
>>
>>>>> Finally, as first approximation, I found it more expedient to
>>>>> randomise
>>>>> the points in the array when reading them.
>>
>> Ah. I understand now.
>>
>> "I found it more expedient to add a random translation to the point
>> values
>> before storing them in the array, as they are read in from the file."
>>
>> (I will admit, it's one of those things that's a bit hard to phrase
>> before 2nd
>> compulsory
>> public education caused me.)
>
> LOL. Not being a native speaker, I have a hard time to formulate them in
> such a way that it may puzzle you... ;-)
>
> Stephen is much better at it than I am... :-)
>
English isn't a very good language to describe such things. You need to
use clauses and sub clause that exceeds common usage. Making the
statements hard to read without deliberately parsing it.
If I understand the sentence below. The only change I would make is:
of one addition *operation*, per point if the...
>>
>> I think it's something that would save the time of one addition per
>> point if the
>> number of points to be plotted exceeded the number of entries in the
>> array, and
>> it would prevent overlap of objects slightly differing in position for
>> the same
>> array entry.
>
> Still something I am not sure about, but I shall try.
>
>>
>>
>>
>>
>>
>>
>>
http://izquotes.com/quotes-pictures/quote-schools-were-designed-by-horace-mann-and-barnard-sears-and-harper-of-the-univ
>>
>> ersity-of-chicago-and-john-gatto-343105.jpg
>>
https://i.pinimg.com/736x/57/14/a2/5714a25f482e091f882ffc1a52fed042--compulsory-education-education-system.jpg
>>
>>
https://i.pinimg.com/736x/c5/9f/3f/c59f3f93df48042001f325789ac42439--public-school-quotations.jpg
>>
>>
>>
>
> I am not familiar with American school education systems,
Nor am I but that won't stop me commenting. ;-)
> but from my
> own experience in Europe, I disagree on most points and provide marginal
> notes for the others. ;-)
>
Quote 1
I think I can agree with this, unfortunately.
Quote 2
I strongly disagree with this.
Quote 3
I quite agree with this.
A note on the British education system. (Note when I say British I mean
English and Welsh. Not the UK as Scotland and Northern Ireland have
their own systems distinct from the rest of the UK.)
The English public schools* were designed to produce officers and
administrators for the Empire. While state schools were designed to
produce craftsmen and clerks. No point in giving the poor ideas above
their station.
*
Here public schools are fee paying and not open to everyone. What you
expect to be called public schools are State schools.
--
Regards
Stephen
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