[Radiance-general] Preview error - unknown object type "ashik2"

[Georg Mischler]

Very interesting, thanks.

My conclusions go like this:

* The useful range of the exponents seems to be between 0 (fully
   diffuse and 10000 (mirror-like). Between 5 and 100 looks like the
   most interesting range.

* To create a plastic-like appearance, the specular reflection should
   be desaturated.

* For a metallic appearance, the specular and diffuse reflections
   should have a similar tint.

Remaining questions:

* What happens when specular and diffuse colors are vastly different?
   I'm expecting something rather psychedelic... Do actual materials
   like that exist?

* Do the diffuse and specular color values depend on each other?
   Eg. should their sum be less than 1?


Cheers
-schorsch


Am 2016-04-22 17:10, schrieb Greg Ward:
> Hi Schorsch,
> 
> The Ashikhmin-Shirley reflectance model is a kind of anisotropic Phong
> model made physically plausible.  It's main advantage over the
> standard anisotropic model in Radiance is that it includes a Fresnel
> modifier, which I use for perfectly smooth surfaces.  Best to read
> their original paper:
> 
> 	www.cs.utah.edu/~shirley/papers/jgtbrdf.pdf
> 
> I added this model to Radiance a few years back with help from Nicolas
> Bonneel, as we were trying to run some comparisons.  Peter
> Apian-Bennewitz also had requested it, so it seemed worthwhile to add.
> 
> Cheers,
> -Greg
> 
>> From: Georg Mischler <schorsch at schorsch.com>
>> Subject: Re: [Radiance-general] Preview error - unknown object type 
>> "ashik2"
>> Date: April 21, 2016 10:34:16 PM PDT
>> 
>> Is there any documentation on how to actually use this material?
>> So far it is only mentioned in a release note and on some presentation
>> slides, but not explained at all.
>> What are eg. useful input values for "specular power"?
>> 
>> Cheers
>> -schorsch
>> 
>> 
>> Am 2016-04-21 18:39, schrieb Greg Ward:
>>> The '_unknown object type_' error is caused by reading in a frozen
>>> octree (generated with "oconv -f") on an older version of Radiance,
>>> before this type was added. You need to update your copy of Radiance
>>> from https://github.com/NREL/Radiance/releases [1]
>>> Chris has the right advice on X11.
>>> Cheers,
>>> -Greg


-- 
Georg Mischler  --  simulations developer  --  schorsch at schorsch com
+schorsch.com+  --  lighting design tools  --  http://www.schorsch.com/