POV-Ray : Newsgroups : povray.binaries.images : Normals have a directional bias : Re: Normals have a directional bias Server Time
15 Jul 2024 08:04:23 EDT (-0400)
  Re: Normals have a directional bias  
From: William F Pokorny
Date: 7 Jan 2021 11:29:01
Message: <5ff736cd$1@news.povray.org>
On 1/6/21 5:33 PM, Hj. Malthaner wrote:
> On 1/6/21 3:48 PM, William F Pokorny wrote:
>> On the linux/Unix/macOS side of things especially, several here offer 
>> releases for branches of one sort or another. Each branch I see as 
>> particularly focused. My povr effort is one of these and it breaks 
>> compatibility in more of a 'POV-Ray 4.0' way than do most others. Povr 
>> is also Linux/Unix based only. I don't use Windows day to day and I do 
>> not understand code development in the Windows environment.
> Seems to be a common problem, at least one that we two are sharing. 

Yep. It's good to remember efforts like Blender have paid core support 
for the - less interesting/fun - day to day development stuff. It's more 
common, I believe, that vital projects of some size have a small team 
where some know windows, others macOS, others web development, etc.

> What is the goal of Povr?

:-) I had to think some about the question! The povr branch happened due 
dead ends elsewhere with respect to what I needed. I'd say:

- Selfishly and foremost, a hobby which is fun.

- Initially, a simpler version of "POV-Ray" supporting the existing 
scene language and the most common features while fixing as many 
longstanding bugs (and broken features) as I can.

- Longer term, I have a list of wild ideas. If I can get to a simpler 
source platform while learning enough programming, I hope to be able to 
try some of the more involved ones. To be able to figure out which ideas 
are good and which are junk.

> I've noticed a bug with media effects behind semi-transparent image maps 
> on transparent objects. Not entirely sure if it's really a bug or if my 
> combination of glass sheets and "holographic" displays was ...

If you believe there's a bug in the current official release, the usual 
place starting post would be povray.bugreports. Or, povray.beta-test, if 
it a problem particular to v3.8 development. Either probably works out 
and cutting the issue down to as simple a scene as possible a great 

Aside: I just noticed the http://news.povray.org/groups/ web page 
description for beta-test wrongly refers to the POV-Ray v3.7 SMP 
beta-test instead of v3.8.

> https://en.wikipedia.org/wiki/Path_tracing

I never know what to do with pointers to the latest and greatest - 
whatever. Usually some good to a particular approach, but different 
devils in the details. At a high level all approaches are faking real 
world effects to some degree.

Yes, if you set up the modeling in more of a real world way, and you 
crush the render with samples you get a very good looking render result. 
You also hide numerical sin in a way not unlike how POV-Ray's AA methods 
or focal blur tend to cover over problems beyond the intended aim of the 

> I think this feature is what makes the Cycles renderer produce better 
> images than PovRay with radiosity. 

Somewhat agree. One place where I believe POV-Ray comes up short is in 
handling finish highlights where radiosity, area lights and ??? are in play.

While I mostly kept a distance from the finish changes Christoph was 
working on for v3.8(1), I believe the aim for many of the changes - like 
always specifying an interior ior - was to better handle surface 
finishes (highlights especially) in a real world way. Expect others here 
know better than me the extent to which my belief is true?

(1) - Being more interested in shapes and actual surface treatments than 
faked ones.

I think mostly these v3.8 finish block changes haven't been exploited to 
date. If they more often were, would the highlight differences compared 
to Cycles (et al) be as dramatic? I don't know for certain, but I 
suspect less so.


At some point what's seen as best or better - what becomes common - is 
just where the crowd of users ends up / happens to be. There is value in 
following; It's easier to grab detailed work of others in terms of code, 
models, materials, maps and such and stick it into your larger scene (or 
program or whatever). Further, it's more likely the things you grab work 
- at least in the main.

Bill P.

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