| Clarification for materials |
 Posted: Sun Jan 27, 2008 9:01 pm |
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| arvinsr |
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| Joined: 08 Jan 2008 |
| Posts: 3 |
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| Hey, Could someone tell me if there is a need to create models for humans and coat it with a face such as "Public on thick upholstered chairs" or do you just coat the surface of the seats with that face?? Thanks
Arvin |
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| Posted: Tue Feb 05, 2008 9:10 pm |
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| Jim Mobley |
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| Joined: 27 Jul 2005 |
| Posts: 134 |
| Location: Foothill Ranch, California, USA |
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| Hi Arvin,
The occupied seating materials, Public in Thinly Upholstered Chairs, for example, include the absorption of the people. You don't need to add additional faces. |
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_________________
Best regards,
Jim Mobley
Sr. Application Engineer
Renkus-Heinz, Inc.
19201 Cook St.
Foothill Ranch, CA 92610 USA
TEL: +1-949-588-9997
FAX: +1-949-588-9514
www.renkus-heinz.com
mailto:jim@renkus-heinz.com |
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| Posted: Tue Mar 18, 2008 4:35 am |
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| Ron Sauro |
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| Joined: 29 Oct 2005 |
| Posts: 27 |
| Location: Elma, Wa |
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| Arvin ... like anything else in this business..."It all depends".
If all you are looking for is statistical data from your model then just a face with the material will be adequate in "most" cases.....
That said.... if you are looking at ETC's generated from Ray tracing or AURA and are planning to auralize a file then modeling the 2 faces of each row of the seating area that make up the horizontal "seat" using 2 sided faces and modeling the vertical seat back the same way.
To make myself clear here..... if you have rows of individual chairs for each person you can substitute a single "pew" in place of that row... the row will consist of a sigle horizontal , 2 sided face and a single vertical 2 sided face the length of the entire row....If the audience seating area has 20 rows then this pew shall be duplicated 20 times....
This is necessary to duplicate the 1st order reflections made by the seat backs and seats in an ETC.
Also a single plane doesnot have the surface area that is the same as those 2 faces added together 20 times in our example... the actual surface area will be in many cases almost doubled...
These faces that are modeled should be placed at the correct height and location to be accurate.
"Scattering Coefficients added to the face are not the same as specular reflections from arrayed seats...
During the tests we have performed on the scattering coefficients of materials we have confirmed ISO- 14797-1 in most cases. The measurments have confirmed that "scattering" is a measurement of random roughness of a surface as long as the vertical displacement variations of the surface do not exceed 1/16 of the sample size....
In full scale measurments of materials we use a circular sample of approx 10.75 ft in diameter. Therefore a vertical displacemet of more than 1/16 of that sample, or approximately 7 inches, is not any longer "scattering" but becomes specular .... and that can be modeled using geometric surfaces.
Since seats are more than 7 inches then the conclusion reached must be that they are not scattering surfaces.
Ron Sauro
NWAA Labs |
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