Christoph Hormann wrote:

> >             brightness 2
>
> Are you sure about that?
> brightness 1 is a fairly universal value that should be realistic in most
> cases.  If you change an existing scene for using radiosity, it's often
> even useful to use lower values.

Well, it happens that I use brightness 2 in scenes where I have direct
photographic references (I just cut and pasted the settings here), so the
choice is only dictated by the similarity between the "real" scene and its
rendered version (I'm not talking about the Cornell box here, but of complex,
real-life pictures). These images also require extremely bright lights.
But you're right,  brightness level depends on the scene. My "Contrast" image
used 1.2 for instance (but it was not based upon a photography). I don't
remember using values lower than 1. It's more an aesthetic choice than a
technical one IMHO.

G.

--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message

Kevin Ellis wrote:
> 
> In the room WIP I posted a while ago which only has one window I have to use
> a brightness of above 3 to be able to see anything except blackness, it all
> depends on how much of the scene is actually lit by direct light. I
> regularly use a brightness of about 2 though.
> 

It's usually better to increase the ambient finish of the light emitting
objects than to increase brightness.  While the fist only brings more
light in the scene, the brightness parameter strongly influences the
colors of the scene in an often unrealistic way.  

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

Post a reply to this message

Lutz-Peter Hooge wrote:
> 
> I had to set it so 0.3, at 1 everything is white... maybe because I use
> colors > rgb 1.

As Gilles said, all finishes need to be changed, if you want to avoid
adapting the colors, you can try to play with the diffuse finish
component. 

> But theres another problem: 0 PPS even with HQOn=0 :-(
> Only if I switch EVERYTHING off (reflections, isosurfaces, arealights
> etc), I can get a preview.
> 

Be sure to turn off all additional light sources (just leave the sun
light).  Of course reflections and isosurfaces slow down things too, but
at least the pretrace should run with 'visible speed'.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

Post a reply to this message

Lutz-Peter Hooge wrote:

> In article <3AC4B8D0.47B58239@gmx.de>, chr### [at] gmxde says...
> > brightness 1 is a fairly universal value that should be realistic in most
> > cases.  If you change an existing scene for using radiosity, it's often
> > even useful to use lower values.
> I had to set it so 0.3, at 1 everything is white... maybe because I use
> colors > rgb 1.
> But theres another problem: 0 PPS even with HQOn=0 :-(
> Only if I switch EVERYTHING off (reflections, isosurfaces, arealights
> etc), I can get a preview.

Strange. I use HQOn=0 on my old, slow Pentium 133. Note that scenes that use
these settings :
- have only one light source
- all objects have ambient = 0
- have few reflections
- have few (or none !) objects with ior
- colors are normal (below rgb 1)

I hope this helps, but as I design images around radiosity, I can't say that
these settings are universal.

G.
--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message

Gilles Tran wrote:
> 
> Well, it happens that I use brightness 2 in scenes where I have direct
> photographic references (I just cut and pasted the settings here), so the
> choice is only dictated by the similarity between the "real" scene and its
> rendered version (I'm not talking about the Cornell box here, but of complex,
> real-life pictures). These images also require extremely bright lights.
> But you're right,  brightness level depends on the scene. My "Contrast" image
> used 1.2 for instance (but it was not based upon a photography). I don't
> remember using values lower than 1. It's more an aesthetic choice than a
> technical one IMHO.
> 

It could be that Indoor scenes often work quite well with increased
brightness, it probably is also mainly a questions what settings the
objects' colors and finishes are tweaked for.  NTL, could you point me to
some pictures using brightness 2?

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

Post a reply to this message

In article <3AC### [at] inapginrafr>, tra### [at] inapginrafr says...

> - have only one light source
Yes, I switched the lamps off.
Only the sunlight remains (arealight, 7x7)

> - all objects have ambient = 0
Done that. 
> - have few reflections
Wel... hmmm... the floor, the sculptures, the window-glass and the water 
are reflective.

> - have few (or none !) objects with ior
The windows glass...

> - colors are normal (below rgb 1)
All the white objects have colors of 1.5-2. Does that slow down 
rendering? With brightness 0.3 the scene look Ok.

Post a reply to this message

In article <3AC4C65C.5F516FD9@gmx.de>, chr### [at] gmxde says...
> As Gilles said, all finishes need to be changed, if you want to avoid
> adapting the colors, you can try to play with the diffuse finish
> component. 
Does the brightness have an influence on rendering speed?

> Be sure to turn off all additional light sources (just leave the sun
> light).
Of course i've done that. But still 0 PPS

Lutz-Peter

Post a reply to this message

Christoph Hormann wrote:

> It could be that Indoor scenes often work quite well with increased
> brightness, it probably is also mainly a questions what settings the
> objects' colors and finishes are tweaked for.

Probably. There's always a lot of tweaking involved in radiosity anyway.

> NTL, could you point me to some pictures using brightness 2?

One at least, uploaded there on a temporary basis (others will come... someday
;-)).
http://www.oyonale.com/temp/classroom.jpg

G.

--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message

Lutz-Peter Hooge wrote:

> > - have few (or none !) objects with ior
> The windows glass...

This could be the main culprit. I have found that a few (and even small)
objects with ior used with radiosity could make a computer weep. I don't
know about a whole pane...

Lots of reflective objects don't help either, but to a lesser extent. The
other problem with using reflective objects with radiosity is the apparition
of ugly black spots. The spot remover is a higher max_trace_level (not the
MTL of 15), which in turns causer slower rendering.

> All the white objects have colors of 1.5-2. Does that slow down
> rendering?

Not that I know.
Personally, I prefer harsh lights with "normal" colors than the other way
round. More a habit than something rational though and I use higher than 1
colors when needed.

G.

--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message

Gilles Tran wrote:

> The spot remover is a higher max_trace_level (not the
> MTL of 15), which in turns causer slower rendering.

"*** note *** the MTL of 15", silly me.

G.
--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message