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Found 2 results

  1. Mantra Coat IOR

    Hi! I've been trying to replicate something similar to Arnold's coat IOR parameter in Mantra. Ideally I'd like to be able to control how much of a coat layer is visible depending on facing angles without affecting the underlying surface, even if this involves breaking the law of conservation of energy. Any ideas on where I could start? Thanks, Nathan
  2. Hello! I have a few questions about rendering glass/refractive materials in mantra. I found more documentation for renderers like vray and arnold for getting good looking glass. Obviously the parameters are a bit different, but more or less they are very similar. Take a look at this photo about glass and vray from this articles: https://blog.turbosquid.com/2014/04/21/turbotips-v-ray-material-part-3-refraction/ For purposes of testing, I decided to create a similar scene rather then in my main project. That way I can work in a simpler environment and also upload my .hip here. My first question are: Many documentations/sites have the index of refraction (ior) for glass. The article above reads: "IOR is a very important parameter to set correctly, in order for your material to look believable. Fortunately, these values have been calculated for all sorts of materials, so there’s no need to guess here." It then states the ior of glass is around 1.5, which checks in with most other places. How can you just say the IOR of glass is 1.5? Wouldn't some glass have different IOR values? Especially if the glass is flat vs spherical or warped. If I try to match the ior values, it looks nothing like the vray photo. IOR of 1.5 is way too distorted to look correct. Please note that my sphere has an inside and a outside (thickness). I set the normals correctly. It seems having thickness to my sphere causes the ior to double. If I delete the inside of the sphere, it is less distorted. So I try setting the IOR to a lower value. However, once I do that, the reflection becomes too weak and super grainy. Mind my actual project is more complex and the reflections are soooooo grainy. Even with a pixel sample of 20 and turning up my light samples, its still too grainy and takes too long. So why can't I change the IOR for reflectivity separately from refraction? The manual says its not realistic, but its just not working for me when it is tied together. If you look at my photos below (you can make them bigger by clicking them) you can see that 1.5 distorts it too much. In my real scene, I have a snow globe. Whats in snow globe is distorted so badly with 1.5 you can't even see what it is. As I said, if I turn the refraction down to 1.1 or 1.2, I can barely see the reflections and they are SO GRAINY. I tried turning up pixel samples, reflection/refraction quality, the sampling on the lights, but its still way too grainy. Any thoughts/tips? glass_test.hiplc
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