<div dir="ltr">Hi Greg,<div><br></div><div>I'm no expert on this topic, but a similar quesiton was answered here: <a href="http://blender.stackexchange.com/questions/2211/how-exactly-does-the-sigma-parameter-affect-the-velvet-shader/2212#2212">http://blender.stackexchange.com/questions/2211/how-exactly-does-the-sigma-parameter-affect-the-velvet-shader/2212#2212</a> a few days ago, if that helps.</div>
<div><br></div><div>Cheers, </div><div>Julian</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/8/12 Greg Zaal <span dir="ltr"><<a href="mailto:gregzzmail@gmail.com" target="_blank">gregzzmail@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hey guys,<div><br></div><div>I'm curious about the implementation of the Velvet shader - I can see that it only reflects light at grazing angles and that the Sigma value is a sort of IOR of some fresnel calculation, but how is it different from simply connecting fresnel/facing ratio to a diffuse shader?</div>
<div><br></div><div>Why the name "Sigma" and not something a little more artist-friendly? Do other renderers use the same term?</div><div><br></div><div>With only a single light source, there's a big black patch near the 0-degree grazing angle, facing directly at camera - is it possible to control the size of this big black patch or is it a fixed constant due to the concept of a velvet shader?</div>
<div><br></div><div>But really I'd just like to know why this shader exists - what it's intended use is and why we can't just create the same effect using other shaders and some fresnel/light vector calculations.</div>
<div><br></div><div>The wiki for the Sigma value is empty, so I'll update it with anything you can tell me.</div><div><br></div><div>Cheers,</div><div>Greg</div></div>
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