Christoph Hormann wrote:
> 
> Kari Kivisalo wrote:
> >
> > I have a theory on why these changes were necessary to produce more
> > pleasing image than the "scientific settings".
> > [photosim stuff]
> 
> Sounds reasonable (although i *try* to judge realism from comparing to reality
> and not to photos).

What I was saying is that due to the limited dynamic range of computer
displays reality has to be compressed to fit a monitor. Photographers
have already done years of research how to compress contrast ratio of
100 000 in a real scene down to 100 which is the contrast ratio in a
good quality glossy photograph. This also happens to be the contrast
ratio of a good monitor. We can invent the wheel again but is it necessary?

Until we have displays that can match the real contrast ratios some kind
of compromise (compression, scaling, chopping, etc.) can't be avoided. Oh,
and those displays would be useless without at least 48bit input :)

> What we should not forget is, that the "scientific settings"
> are only a simplified mathematical model for reality,

All simulations suffer from this but to me the main goal is not to simulate
nature down to the tiniest atom. Simulations offer predictability and stability
so that all the users can be confident that when they use close to real life
parameters the output will be what one would expect. Just look at the first
encounters with the official radiosity feature. Every user had to experiment
with every scene to get decent results. The simulation will get you 80% there,
the rest is up to the artist (textures, lighting, etc.).

The photosim feature requires one additional camera parameter: exposure_time.
This will scale the maximum scene brightness along the transfer curve. There
could be an automatic feature to set the exposure time by measuring the
brigtness on certain spots on a scene just like in the real cameras :) The 
scene would be rendered just once and stored as floats and the photosim
calculations would work on the float values.


______________________________________________________________________
Kari Kivisalo                                  http://www.kivisalo.net

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