POV-Ray : Newsgroups : povray.off-topic : ASAP Server Time
14 Nov 2024 20:55:31 EST (-0500)
  ASAP (Message 1 to 8 of 8)  
From: scott
Subject: ASAP
Date: 7 Nov 2007 17:48:45
Message: <473240cd@news.povray.org>
Been playing around with a *real* (ducks to avoid the flames) ray tracer 
recently.  ASAP is used to model and simulate physically correct optics. 
The dudes who design LEDs use this, as do the people designing lights for 
cars, camera lens systems etc, it seems like it's pretty much the industry 
standard based on the list of customers they say they have.

It's actually quite similar to POV in the way it works.  You set up your 
scene with a script (more about that in a bit).  Light sources can be any 
object or surface, you set the distribution of rays and angles, wavelengths 
and powers.  You give all the surfaces "interface" properties, and bits 
inside get media.  Sounding familiar?  But then instead of any cameras you 
just analyse the rays hitting a certain surface (or group of surfaces) using 
a number of the hundreds of tools built in.

The default "max_trace_level" is 4096 :-)  Apparently when designing optical 
systems that rely heavily on total internal reflection (eg optical fibres 
etc) this needs to be increased...

It won't give you any pretty pictures like POV does, but it will give you 
nice plots of brightness over a surface after light has come from a helical 
filament and gone through 8 lenses :-)

Anyway, the scripting language is what lets it down.  It really is the most 
annoying language I have ever had to use.  There are just so many illogical 
constraints that seem totally pointless.  For example, you can use the @ 
sign to repeat entries, so 4@0 gives you four 0's in a row, or 6@-3 gives 
you six -3's.  The clever bit is you can do -4@1, which will give you four 
1's but alternating the sign, so you get 1,-1,1,-1.  Now, you'd think 
that -4@-1 would give you -1,1,-1,1 ... but no, apparently that's just not 
possible.

Add to that you can't have an if/endif without an else, lots of things have 
to be in certain positions, there's lot of rules about where you *must* have 
whitespace, and of course where you *mustn't* have whitespace (eg 2+3 * 4 is 
illegal), it just drives me mad since I am used to C++ and SDL.

Oh and the referencing system.  Suppose you have defined two objects and you 
want to do something with them... Well, you have two choices, reference them 
absolutely by number, or relatively.  ie you can only say "merge the 2nd and 
5th item created" or "merge the item above and the one two items above 
that".

I'm beginning to love SDL even more...


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From: Invisible
Subject: Re: ASAP
Date: 8 Nov 2007 04:36:15
Message: <4732d88f$1@news.povray.org>
scott wrote:
> Been playing around with a *real* (ducks to avoid the flames) ray tracer 
> recently.

Why would you use ducks to avoid flames?

Oh...



So I take it this thing doesn't use the RGB colour model then? ;-)

Does it handle polarisation too?


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From: Brian Elliott
Subject: Re: ASAP
Date: 8 Nov 2007 04:46:57
Message: <4732db11$1@news.povray.org>
"Invisible" <voi### [at] devnull> wrote in message 
news:4732d88f$1@news.povray.org...
> scott wrote:
>> Been playing around with a *real* (ducks to avoid the flames) ray tracer 
>> recently.
>
> Why would you use ducks to avoid flames?

They stamp them out with their webbed feet.


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From: scott
Subject: Re: ASAP
Date: 8 Nov 2007 05:30:49
Message: <4732e559$1@news.povray.org>
> So I take it this thing doesn't use the RGB colour model then? ;-)

It uses individual wavelengths, it's up to you if you just use 1 or 1000 of 
them in the model.  But all properties and things are dependant on 
wavelength so it works as expected.

> Does it handle polarisation too?

In some limited way, yes, but apparently the next version (with they have a 
beta version of) allows full-blown polarisation simulation (which is why we 
are interested - as you can imagine simulating an LCD needs a pretty good 
polarisation model...)


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From: Invisible
Subject: Re: ASAP
Date: 8 Nov 2007 07:21:23
Message: <4732ff43$1@news.povray.org>
scott wrote:
>> So I take it this thing doesn't use the RGB colour model then? ;-)
> 
> It uses individual wavelengths, it's up to you if you just use 1 or 1000 
> of them in the model.  But all properties and things are dependant on 
> wavelength so it works as expected.

Is the bandwidth hard-coded or adjustable? (E.g., could you try to use 
it for microwaves if you wanted.)

>> Does it handle polarisation too?
> 
> In some limited way, yes, but apparently the next version (with they 
> have a beta version of) allows full-blown polarisation simulation (which 
> is why we are interested - as you can imagine simulating an LCD needs a 
> pretty good polarisation model...)

LOL! Yeah, I can imagine...


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From: Kyle
Subject: Re: ASAP
Date: 8 Nov 2007 08:45:10
Message: <qk46j3907aldgcudg9r2aojjtgc77al8e1@4ax.com>
On Thu, 8 Nov 2007 19:48:20 +1000, "Brian Elliott" <NotForSpam@AskIfUWant> wrote:

>> Why would you use ducks to avoid flames?
>
>They stamp them out with their webbed feet.

o_O

...

Bahahaha!!!


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From: Invisible
Subject: Re: ASAP
Date: 8 Nov 2007 08:55:24
Message: <4733154c$1@news.povray.org>
Squid.


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From: scott
Subject: Re: ASAP
Date: 8 Nov 2007 09:54:56
Message: <47332340$1@news.povray.org>
> Is the bandwidth hard-coded or adjustable? (E.g., could you try to use it 
> for microwaves if you wanted.)

It's not hard-coded, just that all the pre-defined materials only have data 
for roughly visible wavelengths.  In theory there is nothing stopping you 
specifying the material properties for other wavelengths and then using 
those in the simulation...


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