POV-Ray : Newsgroups : povray.binaries.animations : FOG with turbulence-- animation tests Server Time
29 Mar 2024 05:48:31 EDT (-0400)
  FOG with turbulence-- animation tests (Message 11 to 20 of 21)  
<<< Previous 10 Messages Goto Latest 10 Messages Next 1 Messages >>>
From: Bald Eagle
Subject: Re: FOG with turbulence-- animation tests
Date: 11 Dec 2017 10:05:01
Message: <web.5a2e9e133f5614d4c437ac910@news.povray.org>
It's not fog, but I see plenty of turbulence:

https://vimeo.com/241007433


How cool is THAT?!


Post a reply to this message

From: Kenneth
Subject: Re: FOG with turbulence-- animation tests
Date: 12 Dec 2017 19:25:01
Message: <web.5a3072233f5614d489df8d30@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> > Kenneth wrote...
> > I have a tendency to think about maths problems in a kind of 'visual' way. Who
> > knows, I may resort to a step-by-step visual explanation via Photoshop!
>
> Lots of time you can use a spreadsheet to lay things out and give you
> instantaneous results, and have a few extra calculations to keep a check on the
> intermediate and final results.
>
> Think of frames in an animation or different camera views as just another block
> of cells using different numbers...   Then you can see them all at once!

That's an intriguing idea.

I've actually never used a spreadsheet(!); never had occasion to do so. But I
can see that the idea would be useful. If I understand you're concept, I wonder
if some enterprising POV'er has previously come up with a way to put lots of
scene parameter values into a spreadsheet, then to apply those values (somehow)
to a POV-Ray scene, one 'group of values' at a time. As a suitably-correct .ini
text file or include file, for example.

Or maybe I'm way off base :-O


Post a reply to this message

From: Kenneth
Subject: Re: FOG with turbulence-- animation tests
Date: 12 Dec 2017 19:40:03
Message: <web.5a3074bb3f5614d489df8d30@news.povray.org>
Meanwhile...

With more experimentation, I'm getting a better understanding of how fog and
turbulence work together. So I made another animation (only two parts this time)
which might be more understandable, visually.

It uses my experimental 'mist' file again (same black pigments, and zero for all
the finish settings.) I added test objects again but in a more useful way. The
camera is a bit higher up this time.

PART 1 is just a slowly changing' turbulence' value. PART 2 has a 'set'
turbulence, but the camera moves.

Some interesting observations, to help clarify my previous comments:

Purely as a 'visual analogy', it looks like fog is composed of two distinct
parts: the overall smooth depth-based brightening that fog imparts to a scene--
like simply adding a variable gray value to all the pixels based on a
'depth-map' -- and the turbulence effect itself. (Of course, both of those
effects are probably part of the same code construct or paradigm.)

The turbulence splotches are not 'brighter' than the overall fog; rather, the
fog areas 'in-between' the splotches are actually erased (another analogy would
be that those areas have variable transparency compared to the overall fog.) The
brighter splotches are just the 'normal' fog brightness. I checked this in
Photoshop by comparing two renders, one with turbulence, one without.

The turbulence effect itself is *apparently* only on object surfaces (again,
that's just my own analogy of the visual results, not the underlying code
paradigm.) The individual splotches do not 'fill the space' volumetrically
between objects, like media would; they stop at object boundaries...which agrees
with the general idea that fog is just a depth-based brightening of each
camera-ray/pixel, like an overlay (but a more sophisticated 'pseudo-volumetric'
one, 'behind the scenes'.)

Turbulence is MUCH more apparent when the camera is 'inside' the fog rather than
'above' it.

When the overall fog is made thinner (i.e., using an increased  'distance'
value), the turbulence splotches DON'T thin out as much; it's actually a better
way to see the effect. The splotches do become more transparent, just not at the
same rate.

Turbulence  *can* be scaled in 'size' (meaning, the sizes of the individual
bright splotches and the overall appearance)-- but it's done with the TURBULENCE
parameter, not OMEGA. I think the documentation is confused on that point.  And
turbulence scale depends on how close an object is to the camera-- objects in
the distance show a smaller-sized turbulence effect on their surfaces (the
splotches become much smaller.) That's an obvious correlation of course, as with
*any* 3D spatial pattern in POV-Ray when applied to grouped objects-- bumps,
bozo, etc. But the pattern itself (or maybe the pattern's spatial position)
changes somewhat with the camera position-- made obvious when the camera is
animated. (It wouldn't be noticible in a typical still image.)


Post a reply to this message


Attachments:
Download 'fog_animation_test_2.mp4.mpg' (3490 KB)

From: Kenneth
Subject: Re: FOG with turbulence-- animation tests
Date: 12 Dec 2017 19:50:00
Message: <web.5a30786d3f5614d489df8d30@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> It's not fog, but I see plenty of turbulence:
>
> https://vimeo.com/241007433
>
That's the best video example of flocking birds that I've ever seen. Yes, the
'turbulence' effect is quite apparent! ;-)

I wouldn't necessarily like to be UNDERNEATH that bird flock... :-P


Post a reply to this message

From: Bald Eagle
Subject: Re: FOG with turbulence-- animation tests
Date: 12 Dec 2017 22:15:00
Message: <web.5a309ac43f5614d45cafe28e0@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:

> I've actually never used a spreadsheet(!); never had occasion to do so. But I
> can see that the idea would be useful.

Oh c'mon.
Next thing you know, you'll be saying "Oh wow - cool!  This radio thing is kinda
neat...   and this internet thing...   !"
:P


> If I understand you're concept, I wonder
> if some enterprising POV'er has previously come up with a way to put lots of
> scene parameter values into a spreadsheet, then to apply those values (somehow)
> to a POV-Ray scene, one 'group of values' at a time. As a suitably-correct .ini
> text file or include file, for example.
>
> Or maybe I'm way off base :-O

No, I've started experimenting with that, along with the other 100 things I have
on my experimental to-do list.

I had the idea that it would be useful to have calculated values for parameters
and equations in cells, so as you wrote a scene, you'd see if there were any
obvious problems before you parsed the scene and rendered it.

Tons of other things get in the way of having the free time to do that.
Looks like any existing free time will be gobbled up soon.
Details to follow in an off-topic thread.


Post a reply to this message

From: Kenneth
Subject: Re: FOG with turbulence-- animation tests
Date: 12 Dec 2017 22:25:01
Message: <web.5a309c643f5614d489df8d30@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Kenneth" <kdw### [at] gmailcom> wrote:
>
> > I've actually never used a spreadsheet(!); never had occasion to do so. But I
> > can see that the idea would be useful.
>
> Oh c'mon.
> Next thing you know, you'll be saying "Oh wow - cool!  This radio thing is kinda
> neat...   and this internet thing...   !"
> :P
>

Yeah, I thought you would pick up on that... :-P

I think I need to go back to school, to re-learn the basics of modern computing
life...  :-(


Post a reply to this message

From: Stephen
Subject: Re: FOG with turbulence-- animation tests
Date: 13 Dec 2017 04:22:03
Message: <5a30f13b$1@news.povray.org>
On 13/12/2017 03:13, Bald Eagle wrote:
> "Kenneth" <kdw### [at] gmailcom> wrote:
> 
>> I've actually never used a spreadsheet(!); never had occasion to do so. But I
>> can see that the idea would be useful.
> 
You're missing out Kenneth. I generally have a spreadsheet for every big 
project. At the very least it is something to keep my "workings out" in. 
Including images, links, todo's etc.

> Oh c'mon.
> Next thing you know, you'll be saying "Oh wow - cool!  This radio thing is kinda
> neat...   and this internet thing...   !"
> :P
> 

The wireless is kinda neat. I listen to it all day. :)

> 
>> If I understand you're concept, I wonder
>> if some enterprising POV'er has previously come up with a way to put lots of
>> scene parameter values into a spreadsheet, then to apply those values (somehow)
>> to a POV-Ray scene, one 'group of values' at a time. As a suitably-correct .ini
>> text file or include file, for example.
>>
>> Or maybe I'm way off base :-O
> 
> No, I've started experimenting with that, along with the other 100 things I have
> on my experimental to-do list.
> 
I've done something like that but not for PovRay. It was for correlating 
and formatting data in a form suitable for data upload into SAP as a 
text file. It made heavy use of concatenate in one sheet* and that sheet 
was saved using a macro.
I use Excel and Mr Google can supply lots of VBA code to copy.

* Excel spreadsheets (workbooks) can have multiple spreadsheets, 
displayed as separate tabs.


> I had the idea that it would be useful to have calculated values for parameters
> and equations in cells, so as you wrote a scene, you'd see if there were any
> obvious problems before you parsed the scene and rendered it.
> 

I think that is a very good idea and worth spending some time on. Add it 
to your list below. ;)


> Tons of other things get in the way of having the free time to do that.
> Looks like any existing free time will be gobbled up soon.
> Details to follow in an off-topic thread.
> 

Ooo!

-- 

Regards
     Stephen


Post a reply to this message

From: Bald Eagle
Subject: Re: FOG with turbulence-- animation tests
Date: 13 Dec 2017 08:10:01
Message: <web.5a31265e3f5614d4c437ac910@news.povray.org>
Stephen <mca### [at] aolcom> wrote:

> * Excel spreadsheets (workbooks) can have multiple spreadsheets,
> displayed as separate tabs.

Yes, OpenOffice Calc works the same way.
The one I've written for work currently has 21 tabs...

No need to go back to school, Kenneth.  There is that Internet thing I
mentioned, and there are help files and forums (fora?) dedicated to helping you
work out the specifics.


Post a reply to this message

From: Kenneth
Subject: Re: FOG with turbulence-- animation tests
Date: 13 Dec 2017 20:05:00
Message: <web.5a31cc7b3f5614d489df8d30@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:

>
> I've actually never used a spreadsheet(!); never had occasion to do so.

hey, I just thought of a GREAT use for a spreadsheet-- my very first!

I have a habit of taking selected text snippets from newsgroup posts-- of useful
or interesting comments-- and putting them into a text file of my own, for
future examination.

One long, huge text file. :-O

Spreadsheets can use plain text entries in their cells instead of math formulas
(AFAIU)-- so I could put my individual text snippets into cells, cross-reference
them with various/multiple keywords ("pigment ideas", "while-loop tricks", etc
etc) then use the spreadsheet as a sort of 'library catalogue' to easily find
what I'm looking for.

What a BRILLIANT idea, if I do say so myself! I think I'll apply for a
patent!

:-P  :-P


Post a reply to this message

From: Kenneth
Subject: Re: FOG with turbulence-- animation tests
Date: 13 Dec 2017 20:25:00
Message: <web.5a31d1df3f5614d489df8d30@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:

>
> [Fog's current limitations have] me thinking about an alternate approach to
> the problem of fog's object/perspective distortions [on surfaces]. It's based
> on the 'projection' idea, but I need to think about it thoroughly, and about any
> possible ramifications...

Clipka wrote:
> > ...I'm dubious.

Well, try as I might, I concede defeat ;-)  No matter what wierd 'projection'
idea I throw around in my mind, it still requires taking *multiple* ray-samples
of  'volumetric' fog (uh, like true media)-- defeating the idea of it being a
quick-to-render/'inexpensive' solution.

But it was fun to think about anyway.


Post a reply to this message

<<< Previous 10 Messages Goto Latest 10 Messages Next 1 Messages >>>

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.