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28 Mar 2024 09:26:40 EDT (-0400)
  A head full of hair (Message 2 to 11 of 21)  
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From: Bald Eagle
Subject: Re: A head full of hair
Date: 21 Sep 2021 15:05:00
Message: <web.614a2c84467a8aa71f9dae3025979125@news.povray.org>
I sense a Chia Pet thread beginning sometime in the future...

https://www.chia.com/


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From: Samuel B 
Subject: Re: A head full of hair
Date: 21 Sep 2021 20:50:00
Message: <web.614a7d06467a8aa7cb705ca46e741498@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Following an old discussion in 2014:
>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.52dff97746aac96b7a3e03fe0@news.povray.org%3E/?mtop=391452
&moff=21
>
> I took up Robert McGregor's code to see how it could be tweaked to
> obtain a nice haircut. 10000 hairs were planted here. To give a rough
> approximation: parsing took about 10 minutes and complete (stochastic)
> render about half an hour with an i5 machine (Win10; Pov version 3.8).
> The small highlights on the hairs resulted from a combination
> normal/finish choices.

Hey, a fellow i5 owner :) I've got a 6500 here. It's a really good chip.

Ten minutes of parsing seems a little steep. Is the code having to evaluate
every triangle, or just the scalp when choosing to place a hair? And I know
sphere_sweeps can be pretty slow on their own, but I thought they just impacted
the render time. Thirty minutes of render time doesn't seem as terrible as it
could be, but it's still a little high.

Did I ever post my experiments with hair? I was using an .obj-to-.pov converter
and trying to grow hair from a mesh. The way I had it set up was if a triangle
was too small it only had a small chance to grow a hair, otherwise it would try
to grow a certain number of hairs for a given triangle's area. I think I was
using strings of cones though, and not sphere_sweeps.

Sam

P.S. Thanks for reminding me of Wallace and Gromit. It's a great series. Just
watched A Close Shave. What a gem of a flick :D


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From: Thomas de Groot
Subject: Re: A head full of hair
Date: 22 Sep 2021 02:38:15
Message: <614acf57$1@news.povray.org>
Op 21/09/2021 om 21:03 schreef Bald Eagle:
> I sense a Chia Pet thread beginning sometime in the future...
> 
> https://www.chia.com/
> 
> 

Oh LOL! Donald T is absolutely looking better! :-0

-- 
Thomas


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From: Thomas de Groot
Subject: Re: A head full of hair
Date: 22 Sep 2021 03:08:56
Message: <614ad688$1@news.povray.org>
Op 22/09/2021 om 02:47 schreef Samuel B.:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Following an old discussion in 2014:
>>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.52dff97746aac96b7a3e03fe0@news.povray.org%3E/?mtop=391452
> &moff=21
>>
>> I took up Robert McGregor's code to see how it could be tweaked to
>> obtain a nice haircut. 10000 hairs were planted here. To give a rough
>> approximation: parsing took about 10 minutes and complete (stochastic)
>> render about half an hour with an i5 machine (Win10; Pov version 3.8).
>> The small highlights on the hairs resulted from a combination
>> normal/finish choices.
> 
> Hey, a fellow i5 owner :) I've got a 6500 here. It's a really good chip.
> 
<grin> I have an i5 8250 and an i7 8750 here. For some arcane and 
absolutely trivial reasons, I am using the i5 more than the i7, but 
there it is. :-)

> Ten minutes of parsing seems a little steep. Is the code having to evaluate
> every triangle, or just the scalp when choosing to place a hair? And I know
> sphere_sweeps can be pretty slow on their own, but I thought they just impacted
> the render time. Thirty minutes of render time doesn't seem as terrible as it
> could be, but it's still a little high.
> 
Not sure as I have not been monitoring closely what is going on, I guess 
it is the building of the individual mesh2 hairs which sums up. In a 
next run , I shall save/read the hair meshes and that goes faster in the 
end imo. But, not trivial, I had the laptop battery in "best battery 
life" mode; "best performance" mode is certainly faster indeed.

> Did I ever post my experiments with hair? I was using an .obj-to-.pov converter
> and trying to grow hair from a mesh. The way I had it set up was if a triangle
> was too small it only had a small chance to grow a hair, otherwise it would try
> to grow a certain number of hairs for a given triangle's area. I think I was
> using strings of cones though, and not sphere_sweeps.
> 
I don't remember, but that looks interesting, especially the approach 
using triangle sizes. I had not thought of that aspect. I simply used a 
simple trace() function on the skullcap from randomly generated points 
on an external sphere. Pretty fast by itself.

> Sam
> 
> P.S. Thanks for reminding me of Wallace and Gromit. It's a great series. Just
> watched A Close Shave. What a gem of a flick :D
> 
Oh yes, I love them. I was reminded of the scene showing Wallace tasting 
a piece of Moon (on toast) and musing: "Wensleydale?"
> 

-- 
Thomas


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From: Thomas de Groot
Subject: Re: A head full of hair
Date: 22 Sep 2021 08:07:28
Message: <614b1c80@news.povray.org>
Op 22-9-2021 om 09:08 schreef Thomas de Groot:
> Op 22/09/2021 om 02:47 schreef Samuel B.:
>> Thomas de Groot <tho### [at] degrootorg> wrote:
>>> Following an old discussion in 2014:
>>>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.52dff97746aac96b7a3e03fe0@news.povray.org%3E/?mtop=391452

>>>
>> &moff=21
>>>
>>> I took up Robert McGregor's code to see how it could be tweaked to
>>> obtain a nice haircut. 10000 hairs were planted here. To give a rough
>>> approximation: parsing took about 10 minutes and complete (stochastic)
>>> render about half an hour with an i5 machine (Win10; Pov version 3.8).
>>> The small highlights on the hairs resulted from a combination
>>> normal/finish choices.
>>
>> Hey, a fellow i5 owner :) I've got a 6500 here. It's a really good chip.
>>
> <grin> I have an i5 8250 and an i7 8750 here. For some arcane and 
> absolutely trivial reasons, I am using the i5 more than the i7, but 
> there it is. :-)
> 
>> Ten minutes of parsing seems a little steep. Is the code having to 
>> evaluate
>> every triangle, or just the scalp when choosing to place a hair? And I 
>> know
>> sphere_sweeps can be pretty slow on their own, but I thought they just 
>> impacted
>> the render time. Thirty minutes of render time doesn't seem as 
>> terrible as it
>> could be, but it's still a little high.
>>
> Not sure as I have not been monitoring closely what is going on, I guess 
> it is the building of the individual mesh2 hairs which sums up. In a 
> next run , I shall save/read the hair meshes and that goes faster in the 
> end imo. But, not trivial, I had the laptop battery in "best battery 
> life" mode; "best performance" mode is certainly faster indeed.
> 
Just additional info: with laptop connected to the electricity socket 
and on "best performance", parsing while writing away the mesh2 hairs 
(converted by meshmaker.inc) to files, took about 6 minutes, while total 
render time was 22 minutes.
Reading the mesh2 files parsed in 41 seconds, and total render time took 
17 minutes.

In all cases, stochastic settings were: +am3 +a0.01 +ac0.90 +r3, with 
+wt7 for the number of threads to be used.

-- 
Thomas


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From: jr
Subject: Re: A head full of hair
Date: 22 Sep 2021 09:05:00
Message: <web.614b28f3467a8aa75e0fed26cde94f1@news.povray.org>
hi,

Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 21/09/2021 om 21:03 schreef Bald Eagle:
> > I sense a Chia Pet thread beginning sometime in the future...
> > ...
>
> Oh LOL! Donald T is absolutely looking better! :-0

fwiw, I have named your v nice model "Peter Punk".  :-)

(there's a longtime Slackware contributor who goes by "Piter Punk", and the name
came to mind when I saw the superb render)


regards, jr.


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From: Thomas de Groot
Subject: Re: A head full of hair
Date: 22 Sep 2021 09:28:25
Message: <614b2f79@news.povray.org>
Op 22-9-2021 om 15:00 schreef jr:
> hi,
> 
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Op 21/09/2021 om 21:03 schreef Bald Eagle:
>>> I sense a Chia Pet thread beginning sometime in the future...
>>> ...
>>
>> Oh LOL! Donald T is absolutely looking better! :-0
> 
> fwiw, I have named your v nice model "Peter Punk".  :-)
> 
Great! I shall keep the name for later renders.

> (there's a longtime Slackware contributor who goes by "Piter Punk", and the name
> came to mind when I saw the superb render)
> 

Ah! The Brasilian guy? His hair is/was a bit shorter.
> 
> regards, jr.
> 


-- 
Thomas


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From: Alain Martel
Subject: Re: A head full of hair
Date: 22 Sep 2021 12:49:18
Message: <614b5e8e$1@news.povray.org>
Le 2021-09-21 à 08:24, Thomas de Groot a écrit :
> Following an old discussion in 2014:
>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.52dff97746aac96b7a3e03fe0@news.povray.org%3E/?mtop=391452&moff=21

> 
> 
> I took up Robert McGregor's code to see how it could be tweaked to 
> obtain a nice haircut. 10000 hairs were planted here. To give a rough 
> approximation: parsing took about 10 minutes and complete (stochastic) 
> render about half an hour with an i5 machine (Win10; Pov version 3.8). 
> The small highlights on the hairs resulted from a combination 
> normal/finish choices.
> 

What a nice hay ball hair do 😊


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From: Thomas de Groot
Subject: Re: A head full of hair
Date: 23 Sep 2021 02:28:06
Message: <614c1e76@news.povray.org>
Op 22/09/2021 om 18:49 schreef Alain Martel:
> Le 2021-09-21 à 08:24, Thomas de Groot a écrit :
>> Following an old discussion in 2014:
>>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.52dff97746aac96b7a3e03fe0@news.povray.org%3E/?mtop=391452&moff=21

>>
>>
>> I took up Robert McGregor's code to see how it could be tweaked to 
>> obtain a nice haircut. 10000 hairs were planted here. To give a rough 
>> approximation: parsing took about 10 minutes and complete (stochastic) 
>> render about half an hour with an i5 machine (Win10; Pov version 3.8). 
>> The small highlights on the hairs resulted from a combination 
>> normal/finish choices.
>>
> 
> What a nice hay ball hair do 😊

Thanks! I would hate to take a comb through it... :-0

-- 
Thomas


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From: Samuel B 
Subject: Re: A head full of hair
Date: 23 Sep 2021 18:05:00
Message: <web.614cf9b5467a8aa7cb705ca46e741498@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 22/09/2021 om 02:47 schreef Samuel B.:
> > Hey, a fellow i5 owner :) I've got a 6500 here. It's a really good chip.
> >
> <grin> I have an i5 8250 and an i7 8750 here. For some arcane and
> absolutely trivial reasons, I am using the i5 more than the i7, but
> there it is. :-)

Based on user benchmarks, the i5-6500 seems to perform a bit better than the
i5-8250(U), but the i7-8750(H) outperforms both. (The number of cores, however,
do factor into all this.)

From what I've seen, CPU performance has been rather incremental over the years
when it comes to the hard stuff like raytracing... Certain things will always be
slow to parse and/or render, which is why I try to find faster ways of doing
things when possible...

> > Ten minutes of parsing seems a little steep.(...) Thirty minutes of
> > render time doesn't seem as terrible as it could be
> >
> Not sure as I have not been monitoring closely what is going on, I guess
> it is the building of the individual mesh2 hairs which sums up. In a
> next run , I shall save/read the hair meshes and that goes faster in the
> end imo.

What's the shape of the hair follicles? If they are round, how many sides do
they have?

And if you're using includes, then perhaps they are the reason for your high
parse times. So if it's at all possible, maybe try copying all the necessary
macros &/ functions into your scene file, since using includes in any heavy way
is much slower than referencing local code. (But I think you knew this already.)

> But, not trivial, I had the laptop battery in "best battery
> life" mode; "best performance" mode is certainly faster indeed.

I've got a 2012 laptop, and I've been using it without its battery for a number
of years now. (The battery's fine, but I like to extend its life by not using it
;D) The laptop just stays plugged in with high performance mode enabled at all
times. Enabling best/high performance really does make a difference.

An unfortunate thing happened recently... I've got the laptop perched on two
small planks (for air flow) on top of my desktop computer. It's up high so that
the laptop can get a better signal. Well, one night I was a little careless and
didn't notice the planks were slipping... Anyway, the laptop fell off and I put
it back thinking nothing of it. But the next day I realized the earbuds jack was
askew... Turns out the port got bent when everything fell over, and now it only
transmits a signal through one channel D: And I can't observe the contacts
without taking the whole thing apart (I've opened the laptop plenty of times,
but never removed /everything/). My only other option is cutting a hole through
the plastic over the problematic area. but at least the thing is still
functional in all other respects :P

> > Did I ever post my experiments with hair? I was using an .obj-to-.pov converter
> > and trying to grow hair from a mesh. The way I had it set up was if a triangle
> > was too small it only had a small chance to grow a hair, otherwise it would try
> > to grow a certain number of hairs for a given triangle's area. (...)
> >
> I don't remember, but that looks interesting, especially the approach
> using triangle sizes. I had not thought of that aspect. I simply used a
> simple trace() function on the skullcap from randomly generated points
> on an external sphere. Pretty fast by itself.

The code for the hair still exists somewhere, but it is not readily available. I
do, however, have at hand the program I wrote to convert .obj files to
POV-readable data. (I may have posted it once; I'll have to check.) The program
exports arrays, with options for additional data such as neighboring faces and
vertices. (If you remember some preliminary stuff I posted a while back for an
IRTC competition, that's what I was using to make flagstones/stone walls out of
blobs.)

> > P.S. Thanks for reminding me of Wallace and Gromit. It's a great series. Just
> > watched A Close Shave. What a gem of a flick :D
> >
> Oh yes, I love them. I was reminded of the scene showing Wallace tasting
> a piece of Moon (on toast) and musing: "Wensleydale?"

Lol. Based on how often he mentions that particular cheese, I'd say it's his
favorite :)

After you originally mentioned W&G I got to thinking... There might have a way
to make a convincing clay material, complete with fingerprints. It involves the
use of slope patterns and projected normals...

Sam


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