It seems to me that a public material surface properties library would
be a really valuable thing. I don't know that I'm putting myself
forward to make it work, and I'm not really sure what it would entail,
but do you-all have opinions on this?
Randolph
Randolph Fritz wrote:
It seems to me that a public material surface properties library would
be a really valuable thing. I don't know that I'm putting myself
forward to make it work, and I'm not really sure what it would entail,
but do you-all have opinions on this?
Hi Randolph, hi all,
two thoughts:
How does a user know the real visual appearance of the "light yellowish
wood" he finds in the library ? Plus variants like "polished" "slightly
polished" etc. One may supply photographs of the real thing, but I'm not
sure that's good enough.
Secondly, measuring materials (spectral and/or angular) is, even with
automated and fast machinery, some work, data processing and modeling
are too, especially for an easily increasing number of materials, such
as in a catalogue.
It'll be very valuable to get feedback from users how they would use any
form of catalogue - education or project work, for filling in data when
no materials are given in a project or for matching a given material in
a project ?
I had the idea of compiling a reference sample catalogue, around 8-12
material samples (e.g. 3x6cm) initially, plus their measurement data and
fitted Radiance model. Would be quite handy for projects and feasible
too, using my 12 year old, still used and fully automated
gonio-photometer at FhG-ISE or a newer one, but I doubted there'll be
enough interest.
Any comments welcomed
-Peter
--
pab-opto, Freiburg, Germany, www.pab-opto.de
two thoughts:
How does a user know the real visual appearance of the "light
yellowish wood" he finds in the library ? Plus variants like
"polished" "slightly polished" etc. One may supply photographs of the
real thing, but I'm not sure that's good enough. Secondly, measuring
materials (spectral and/or angular) is, even with automated and fast
machinery, some work, data processing and modeling are too, especially
for an easily increasing number of materials, such as in a catalogue.
Well, it's still a good start, for the newbies (like me) especially.
Learning by trial and error is so time consuming; a "starter set" of
materials that are maybe from a common pallete, that could be
used as a starting point for experimentation could help the trial and
error process move along a bit more quickly.
It'll be very valuable to get feedback from users how they would use
any form of catalogue - education or project work, for filling in data
when no materials are given in a project or for matching a given
material in a project ?
Here's my perspective, coming from the Lighting Designer-who-
uses-Lightscape side of the fence: we tend to use "value-only"
materials in Lightscape (ie, hue=0, saturation=0, value=.xx, where
".xx" is the "reflectance" of the material). The limited reflection &
transmittance capability of Lightscape does not allow for really
complex material definitions. In addition, most other lighting
design calculation programs used in the US (Lumen Micro, AGI,
etc) don't support anything more than a reflectance value. So long
ago I adopted this simplified method of material definition in
Lightscape. Our models are greyscale representations of spaces.
We like to think of them as "electronic foam core models". We shy
away from hyper realism in the interest of time, and also in the
interest of reducing the number of variables.
But I've always wanted to learn Radiance, and the latest debacle
with Lightscape going the way of the dinasour (and the advent of
OS X) have pushed me into the radiance camp at long last. So
now I have this wonderfully capable calculation program, and
suddenly have all these possibilities in terms of materials and
reflection models. It's exciting, but daunting.
So, a catalog of materials with known properties, perhaps tested
with your gonio-photometer would allow me to create Radiance
models that I could stand behind. Even if it's not all-inclusive, at
least if there were a selection of common materials with known
performances, we could use them and then extrapolate as
necessary, until a more fully-developed library is created.
I had the idea of compiling a reference sample catalogue, around 8-12
material samples (e.g. 3x6cm) initially, plus their measurement data
and fitted Radiance model. Would be quite handy for projects and
feasible too, using my 12 year old, still used and fully automated
gonio-photometer at FhG-ISE or a newer one, but I doubted there'll be
enough interest.
Well, I for one *am* interested!! I actually have been meaning to
ask you if your device is available to test submitted samples,
Peter. I'm involved in a 1/2-scale gallery mockup right now, costing
the museum client hundreds of thousands of dollars, because
Lightscape was in no way up to the challenge of testing the
glazings. Radiance probably could have, but not without good
BRDF data. Only way to obtain that is with your gonio-photometer.
Would this be an option in the future, perhaps for a fee? We send
you samples, you send us data files?
:::::::::::::::::::::::::::::::::
Rob Guglielmetti
http://home.earthlink.net/~rpg777
On 2 Aug 2002, at 15:59, Peter Apian-Bennewitz wrote:
Hi,
its an iteresting coincidence that this question is asked right now. I
did spend some work on this, too, however tackling the topic from a
completely different, namely the aesthetical/visualisation point of
view. It will be a part of my short presentation at the workshop in
sept/oct.
Generally, I judge something like a materials library a necessary thing
not only for beginners but for all users, especially the ones without
programming experience. As Rob already pointed out, this doesn't have to
be a 1000-entry catalogue, just a set of examples which covers usual
applications and, more important, offers a guideline to the matter for
each user to create new descriptions fitting the individual needs.
Applying a material description to an object is already difficult enough
within Radiance :), but this is another matter..
-cb
Hi!
It'll be very valuable to get feedback from users how they would use any
form of catalogue - education or project work, for filling in data when
no materials are given in a project or for matching a given material in
a project ?I had the idea of compiling a reference sample catalogue, around 8-12
material samples (e.g. 3x6cm) initially, plus their measurement data and
fitted Radiance model. Would be quite handy for projects and feasible
too, using my 12 year old, still used and fully automated
gonio-photometer at FhG-ISE or a newer one, but I doubted there'll be
enough interest.
I think a even little catalogue with maybe a few materials would be great,
not with the standard materials, but with those one can't easily describe
without special measurement hardware (e.g. I still don't know how to describe
a surface of gold mosaic). I am working with radiance for university projects
here. On the other hand, I have my little collection of marble surfaces that
I got from my current work.
BTW, while not really fitting to the subject line, do you have a MacOS X
version of rshow? A friend of mine started with radiance on OS X, and there
is a nice previewer missing 
CU Lars.