azimakberali opened this issue on Nov 07, 2011 · 12 posts
azimakberali posted Mon, 07 November 2011 at 7:29 AM
Hello all,
I am using Poser 7 and would please really like to know how I can achieve Chrome effects like the image above. I am relatively new to Poser so would appreciate as simple an explanation as possible. Also screenshots of the Material Room or any other settings would be greatly appreciated.
Thank you so much
26Fahrenheit posted Mon, 07 November 2011 at 7:39 AM
if you think about it... chrome is a metalic reflection ..
so with REFLECTIONS you get alway there..
and a reflection MAP or reflection of the scene ..
i
Chris
hborre posted Mon, 07 November 2011 at 8:09 AM
The problem with reflection maps or scenes, they don't always match the background stage. If you are only interested in creating an image as above, then a map would be enough. But look closely, the reflections do not match what the character is wearing. However, if your image will be placed in a populated scene, you would like to have your chrome actually reflect what is present. Outdoor scenes will require a skydome, indoor scenes should have a completely enclosed set.
azimakberali posted Mon, 07 November 2011 at 8:54 AM
Quote - The problem with reflection maps or scenes, they don't always match the background stage. If you are only interested in creating an image as above, then a map would be enough. But look closely, the reflections do not match what the character is wearing. However, if your image will be placed in a populated scene, you would like to have your chrome actually reflect what is present. Outdoor scenes will require a skydome, indoor scenes should have a completely enclosed set.
Could you please briefly describe to me how to do each of the three methods i.e
How to apply a reflection map to an object
How to apply a skydome to an object
How to create a completely enclosed set.
I'd really appreate it. Thank you
Anthanasius posted Mon, 07 November 2011 at 11:57 AM
As said before, you need something to reflect. Generaly with reflection i never use specular node but with it you "simulate" the sun size.
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bagginsbill posted Mon, 07 November 2011 at 12:08 PM
Use the shader Anthanasius posted - that is a very good Chrome. Very accurate amount of reflection with a good Fresnel falloff.
For a full 360 degree environment, get my free environment sphere.
(Found in my free stuff - follow my signature link.)
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Anthanasius posted Mon, 07 November 2011 at 2:24 PM
azimakberali posted Mon, 07 November 2011 at 9:48 PM
Thank you so much "Anthanasius" and "bagginsbill". Really appreciate your help.
Could you please also tell me how to put an environment/background in my poser scene? Like the ground and sky in "Anthanasius's" Teapot image. I'm sorry if this sounds like a silly question but my knowledge of Poser is very limited.
Thank you so much once again.
hborre posted Mon, 07 November 2011 at 9:56 PM
As BB mentioned, download his environment sphere from his free stuff site. There is also some panorama images available for download you can use with the sphere.
Miss Nancy posted Mon, 07 November 2011 at 11:51 PM
suggest blinn node for chrome alt spec in PP2012 and earlier, if simulation of certain indirect specular fx desired, when combined with surface defects/roughness. anthan's shader is related to the schlick approx. of the fresnel shader in later versions.
Anthanasius posted Tue, 08 November 2011 at 12:35 AM
In Ppro 2012 in the reflect value put a fresnel blender node
Inner =black
Outer = white
Fresnel = 30
For the exemple i use the skydome from dystopia (free at daz ;) )
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bagginsbill posted Tue, 08 November 2011 at 6:39 AM
I have been studying (and personally researching) metal reflections for months now. We can get away with "simple" IOR to approximate metal behavior, but it isn't all that accurate. In fact, when you get into high "simple" IOR, such as 30, the curve it makes is not the curve of reflectivity that metals actually produce. To get that curve, you have to either use the complex IOR, given as values n and k, or use Schlick's approximation, but boosted into higher ranges, as Anthanasius did in the posted shader. The boosted approximation is more accurate than using the highly accurate PP2012 Fresnel_Blend node. The FB node only does "simple" IOR (given only a single numeric value) and it is correct only for dialectrics, not for metals. A high dialectric IOR produces a severe drop near 90 degrees that is not how real metals behave.
For any given "simple" IOR=n, the reflection value at normal incidence is ((n-1)/(n+1))^2.
IOR=30 corresponds with a reflection value at normal incidence of 87.5% - far too high for chrome, but reasonable for silver. A more correct "simple" IOR for chrome would be 10 - as this would yield a 67% reflection value. Of course, "artists" who use words like chrome but don't realy mean chrome are free to do any reflection value or IOR that suits the situation.
The actual IOR of chrome (and all other conductors) is a pair of numbers, and they are never above 4. I still do not have a straight answer for the math, which is very difficult to follow.
The normal indicence reflection value with k != 0 (metals) is:
((n-1)^2 + k^2) / ((n+1)^2 + k^2)
You can see from this that when k is 0, the value reduces to the dialectric case.
As an example of a typical metallic IOR, suppose n = 2 and k = 2. In that, the reflection value at normal incidence is:
(1 + 4) / (3 + 4) = .714
Whereas when k is 0 it is
1 / 3 = .333
The value k represents attenuation of light passing through the metal. It happens because the electrons are free to move in a metal, while not free to move in a dialectric. The movement of the electrons creates a secondary electromagnetic field that opposes the transmission of energy through the material.
Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)