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Subject: Esoterics?


bwtr ( ) posted Fri, 15 April 2005 at 8:47 PM · edited Wed, 20 November 2024 at 3:41 AM

The little black hole of information in Cajomi's great Landscape Tute highlights the difference in basic knowledge by the Gods compared to we of the hoi poloi. Firstly, starting with Preferences for the Shader Editor. What features, benefits, disadvantages are gained by checking/unchecking those 3 boxes in various order? Secondly--because this query list can grow exponentially--is any "book"--using Carrara terminology--available to supplement the manual. As an ex pro photographer the use of "fresnel" buy the community--and "baking!!!"--makes my poor brain shatter into uselesness. Help!

bwtr


Sardtok ( ) posted Sat, 16 April 2005 at 7:15 AM

As an ex-photographer you should know what fresnel is (or at least a fresnel lamp), the relation between the fresnel lamps and fresnel shaders are pretty simple although I had no idea what they were at first. Basically, this Fresnel guy came up with some weird refraction calculations/laws. They were used when making the glass lens for the spots which are now known as fresnels to give a nice soft light. But they can also be used to calculate how transparent, or how reflective a surface is according to the angle between the light and the viewer. Baking means that a shader or part of a shader is converted into a texture map (going from procedural to image, or how the light hits it can be calculated into an image, and so on).


kelley ( ) posted Sat, 16 April 2005 at 12:38 PM

file_221875.jpg

As I understand the Fresnel Lens, it's a lens with circular concentric ridges [the red line shows cross-section] that difusses the light in [nearly] all directions so that there's no sharp edges when you project it...as in a stage production. [I didn't continue the lines all the way to the center] However, if you're on the backside of a Fresnel, it collects light like peripheral vision and you can see nearly 180 deg. left and right. A while back, plastic sheet Fresnels were popular to hang in windows to gather sunlight.


Kixum ( ) posted Sun, 17 April 2005 at 4:25 PM

Fresnel effects refer to the relationship between the angle of incident light, the angle of the surface and the angle to the viewer (ie, the angle that light bounces from the light source, off the surface, and to the viewer). There are materials which will reflect light differently based on the angle. Some surfaces will only reflect certain color bands depending on the angle. Other surfaces only change what we call highilght, shininess based on angle. Other surfaces have different strengths of reflection based on angle. The Fresnel lens is a simple lens that can transmit light focusing a wide point source into a single beam using a material (like glass) of the same refaction index. This was really important a long time ago because people needed lenses that would produce beams for light houses from a bulb (or fire). You could do this with a Fresnel lens and construct it rather easily. Lenses like the camera lenses we have now which have smooth rounded continuous surfaces are actually a serious challenge to construct (especially if they have to BIG). So Fresnel lenses are simple layered "steps" of glass that are in stages to coarsely represent the smooth like lens we can make now. -Kix

-Kix


bwtr ( ) posted Sun, 17 April 2005 at 8:15 PM

Perhaps one needs to be under 70! I agree with the Fresnel descriptions but the relationship of the theory with Shader Ops and the Toxe free shaders eludes me. Sardtoks description of Baking--and another look at Juliens Baker plugin--still makes me wonder how "baking" is the description. Any one up to tackling the Preferences question-- or Carrara Dictionary say? Thanks all. Brian

bwtr


ShawnDriscoll ( ) posted Sun, 17 April 2005 at 8:58 PM

I think baking a 3d object means putting a textureless object in a scene. Then letting whatever lighting and shading and reflected color and textures hit the object. And create texture maps (bake) onto the object's polygons the info it's collected. Then render the scene with just the texture map enabled on the object to speed up rendering. I may be totally wrong on this. But this is what I was brought up in the world believing.

www.youtube.com/user/ShawnDriscollCG


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