GI Power, Motion blur, etc

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Erufailon
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Joined: Wed Jan 07, 2004 11:48 am

GI Power, Motion blur, etc

Post by Erufailon » Wed Aug 11, 2004 12:46 pm

Hi,

Gi power:
It used to effect every light, and every GI present, but now it only effects the hemisphere that is around the scene. This makes it impossible to create well lit indoor scenes with only a few dull light sources, which don't create bright specularity on shiny objects. Can we get it back please. (Don't know if it's a bug or a wad)

Motion blur:
Now it's possible to create animations with yafray very easily. But it can't really get high quality without motion blur. It needs to be implemented IMHO.

etc:
DOF needs IPOs to enable us to animate camera focus. It would add a lot to realism.

Not complaining here, just a few ideas (well, except for the first on, that's a complaint :) ). Love blender.

eeshlo
Posts: 73
Joined: Wed Nov 06, 2002 10:02 pm

Post by eeshlo » Wed Aug 11, 2004 9:23 pm

Erufailon wrote: Gi power:
It used to effect every light, and every GI present, but now it only effects the hemisphere that is around the scene. This makes it impossible to create well lit indoor scenes with only a few dull light sources, which don't create bright specularity on shiny objects. Can we get it back please. (Don't know if it's a bug or a wad)
In the very first implementation it did control the pathlight indirect light power (not lighting directly, just the indirect 'bounced' light). However, Jandro didn't quite agree with this (or rather it was difficult to control some things in other ways) and changed it to control objects which have emitting materials, which include backgrounds. It also (confusingly) controls arealight power.
In any case, as I said before, adding an extra button to control the *actual* GI power would be no problem really.
Motion blur:
Now it's possible to create animations with yafray very easily. But it can't really get high quality without motion blur. It needs to be implemented IMHO.
Motionblur is not really trivial to implement in yafray. It's not impossible (I have a basic implementation in my own renderers but they work quite different from yafray), just not very easy to implement. The basic method would need to sample in the specified time interval (randomly usually, so another source of noise), but this would require knowledge about the objects start and end points (also, the object could deform), and the path it follows in that time interval.
The simplest method would be to let Blender handle it, which would solve all of the above, so rendering several frames, mixing the end result. But that would result in even longer rendering times, not something most people would be happy with.
etc:
DOF needs IPOs to enable us to animate camera focus. It would add a lot to realism.
All of the last additions to Blender for yafray were done in a rather short time (the extra light stuff in practically two days for example) since I have been away for quite some time, unable to do anything. So it was all a bit hurried work, of course things will be improved further and new things added eventually.
So yes, focus point animation is of course on the todo list.

Erufailon
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Joined: Wed Jan 07, 2004 11:48 am

Post by Erufailon » Wed Aug 11, 2004 9:32 pm

Thanx.

So I personaly liked the first implementation, the new one makes said indoor scenes almost impossible to create.

Yes, I know Motion blur wouldn't be all the simple to implement, and it would make things slower, but hey, it's not like everyone has to use it :)

eeshlo
Posts: 73
Joined: Wed Nov 06, 2002 10:02 pm

Post by eeshlo » Wed Aug 11, 2004 9:49 pm

Erufailon wrote: So I personaly liked the first implementation, the new one makes said indoor scenes almost impossible to create.
'Impossible' seems a bit of an exaggeration, not everyone has problems with it. And as I said, it would only control indirect light, not direct light.
If you can show me something you think is impossible to light properly, maybe I can say something to help (or not...).
Increasing GI power is really only necessary if you want exaggerated colourbleeding or things like that, which can be nice sometimes of course.

Erufailon
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Joined: Wed Jan 07, 2004 11:48 am

Post by Erufailon » Thu Aug 12, 2004 2:44 pm

http://web.axelero.hu/ceze1/test2.jpg

So, with this one if I remember correctly I could just increase the GI power and the brightness of the lamp reflected on the ball stayed as it is, but the whole room was well lit.
Now if I would increase the GI power, it would do nothing. If I would increase the lamp's energy, it would be like this:

http://web.axelero.hu/ceze1/test3.jpg

I said it's almos impossible because I could fake GI by placing other light sources, I guess, but
1, I can't get good enough results because I suck at faking GI
2, that would defeat the purpose of GI
:)

(I could get the desired result with Ambient Occlusion. BTW, why was it decreased to the maximum energy of 3? I liked 10 better :) )

And after editing the XML :

http://web.axelero.hu/ceze1/test4.jpg

(Low sample count that's why it's so patterny, but I think it demonstrates my point clearly. And xml editing is not an option with animations.)
So you see that I'm not cheating, another render from blender by increasing the lamp's energy. This one better matches the xml edited render.
http://web.axelero.hu/ceze1/test5.jpg
(And the lighting looks different, which is also something that would be hard to simulate. I can push gamma way up, that will give in this case somewhat good results, but the lighting will be different, tho it solves the first problem.)

eeshlo
Posts: 73
Joined: Wed Nov 06, 2002 10:02 pm

Post by eeshlo » Fri Aug 13, 2004 9:34 pm

Sorry for the late reply...
(I could get the desired result with Ambient Occlusion. BTW, why was it decreased to the maximum energy of 3? I liked 10 better )
I suppose you mean Blender's AO. It seems maximum was actually 50 initially, but I guess Ton didn't see the need for that high a range. In the commitlog he says it was useless.
I don't have anything to do with AO code anymore btw, I only submitted the original patch.
(And the lighting looks different, which is also something that would be hard to simulate. I can push gamma way up, that will give in this case somewhat good results, but the lighting will be different, tho it solves the first problem.)
It is better to use the exposure parameter instead of gamma, it better 'compresses' the high brightness values, but maybe that is what you actually meant.

You could try using an arealight, then will you will still be able to use the current GI power parameter. Unless you changed the lighttype for the edited xml file, as you can see increasing the lightpower has the effect of making it look like an arealight anyway. It isn't really physically correct either, because objects scatter more light than they receive. Not that that is a problem to get the effect you want of course, and other renderers have things like 'GI multiply' type parameters too.

In any case, you will get your extra button, don't worry! ;)

Erufailon
Posts: 0
Joined: Wed Jan 07, 2004 11:48 am

Post by Erufailon » Sat Aug 14, 2004 3:04 pm

Thanx :)

And can we get a button to set our own GI sample count, just like how it's now possible to turn Auto AA off, please? :D

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