Anim8or Community

General Category => General Anim8or Forum => Topic started by: Itinaeroa on February 15, 2014, 12:15:42 am

Title: Material Attributes - Getting them right
Post by: Itinaeroa on February 15, 2014, 12:15:42 am: Hi there, I'm currently playing around with the material attributes. See attachment.

I called the blue object's attribute 'specular' and the string 'phong' (didn't seem to do anything)

I called the red object's attribute 'specular' and the string 'reflection' (gave a nice reflection)

I called the green object's attribute 'class' and the string 'dialectric' (it's seems to have worked the way I expected)

I called the last object's attribute 'class' and the string 'transparent' (It's meant to be yellow and transparent)

My question is, why is the last object seem to be fully reflective and not transparent yellow?

Thanks for your help.
Title: Re: Material Attributes - Getting them right
Post by: kreator on February 15, 2014, 02:51:01 am: Did you add an IOR attribute to the Transparency class ?
Title: Re: Material Attributes - Getting them right
Post by: Itinaeroa on February 15, 2014, 02:25:39 pm: Hmmm...

I'm not sure how to do IOR.

I made an attribute called IOR but I don't know where to put the value?
Title: Re: Material Attributes - Getting them right
Post by: kreator on February 16, 2014, 01:34:19 pm: Attributes

New..class
string: transparency
New
IOR
float: 1.33

IOR = Index of Refraction tables for these can be looked up on the internet.

ANIM8ORWORLD.com (http://Anim8orworld.com/Forum/index.php) FACEBOOK GROUP (https://www.facebook.com/groups/Anim8orWorld/) FACEBOOK PAGE (https://www.facebook.com/Anim8orWorld) COMPETITIONS (http://www.anim8orworld.com/Forum/index.php?board=26.0)
Title: Re: Material Attributes - Getting them right
Post by: Itinaeroa on February 16, 2014, 03:41:08 pm: I saw the excel spreadsheet on this forum too, read it, and tried to implement it but just couldn't get it right. Thanks for the help!
Title: Re: Material Attributes - Getting them right
Post by: ENSONIQ5 on February 17, 2014, 01:50:37 am: I find this (http://www.anim8or.com/learn/raytracer/index.html) to be the best reference for ART materials. I render in Anim8or rarely and often need a reminder!
Title: Re: Material Attributes - Getting them right
Post by: Itinaeroa on February 17, 2014, 09:52:29 am: Thanks ensoniq5. As a novice I found it difficult to understand. Kreators simple format was much easier.

New..class
string: transparency
New
IOR
float: 1.33

I think dielectric has the better 'look' for what I'm after but will keep experimenting :)
Title: Re: Material Attributes - Getting them right
Post by: Steve on February 22, 2014, 05:17:46 pm: I got lazy and never finished adding the chapter on Ray Traced materials to the on-line manual. Here's the section on attribute "class" = "transparent":

Class transparent
This transparent class is a simple model for diffraction of light through transparent materials. There is also a slight reflection off the surface. The amount of transparency is set with the normal transparency value for a material. It has one additional attribute:
• IOR - the index of refraction. This represents how much light is bent as it enters or leaves a transparent material. Useful values include 1.0 (air - no difference than outside of a material), 1.33 (glass), 1.49 (Plexiglas) and 2.42 (diamond).
Rendering transparent materials can take a very long time. Each primary ray (from the camera) can trigger tens or even hundreds of rays since each interaction generates up to two child rays, the reflected ray and the transparent ray.
The image below show 5 spheres with and IOR of 1.0, 1.1, 1.2, 1.3 and 1.5, and a transparency of 0.1:

And take a look at the files linked off of the ART Ray Tracer notes that are posted if you haven't already. The example file to make this image is there. http://www.anim8or.com/learn/raytracer/index.html (http://www.anim8or.com/learn/raytracer/index.html)