Progress

A busy week. I’ve textured the blocked in parts. And looked up some information about shaders. The shaders I’m gonna use is mia material, these shaders can not be viewed in the viewport and therefore I assigned blinns while I was texturing and then I changed them later on. The reason why I choosed mia materials, is because they really got good options for creating belivable materials. They are physically accurate with many optimizations and performance enhancers. Although they may come with presets, its good to know how to tweak them. For my project I’m going to mimic five different materials: stone/concrete material, shiny metal, matte metal, paper/cardboard materials and wood material.

For a stone material the diffuse roughness parameter should be rather high, the more porous the stone is, the higher this value should be. Reflection gloss should obviously be low and you can only use refl_hl_only as well. The reflectivity should be around 0.5-0.6 with brdf_fresnel off and brdf_0_degree_refl at 0.2, with the brdf_90_degree_refl at 1.0.

For the wood I use refl gloss of 0.5, refl samples of 16, reflectivity of 0.75

For the metal materials I checked the box refl metal, it will allow a nice blending between diffuse shading and glossy reflections.

Reflections is very render consuming, so when it comes to optimizing the shader, you should consider tweaking this parameter of the shader. Tweaking the reflection fall off cannot only give better results (as objects maybe 50 meters away won’t reflect), but it will also give you faster render times. For my indoor scene I’m also going to use the re_fallof_color as it tends to be useful for indoors scenes

During this week I’ve also tweaked the geomtery by around 150 000 tris. I still has some issues concerning the rendering. (which actually was my biggest fear, when I started this project.) At times it won’t render at all! But I hope that I will sort that out soon.

I will also go a little more indepth with the lighting as I tested both to use lights with and without FG:
I used both area lights and spot lights when I played around with the no FG settings. My workflow when not using FG was that, I started to light in maya software with depth map shadows filter size 7, for efficiency and then turn to mental ray with raytrace. When placing out the bounce lights it’s good to know that warm colors tend to bounce more. Area lights that are placed in the window should also have an opposite area light dropped to half the intensity. The benefits of this workflow is that you can place out lights really fast and get a fast result. Although in complex realistic scenes I felt that the result turned out to be unsatisactory, and placing out bounce lights in a big scene actually took longer than using FG. So that is why I in the end went with FG. Also, for a realistic scene it’s very important to remember to set the falloff to quadratic. As if the default is used (linear) the light won’t decay properly. For linear lights= intensity=decay/radius For a quadratic setting the formula goes intensity=power/ (radius*radius) which means that it requires a high intensity setting, but the falloff will be correct. This could also be improved by using a blackbody which will give you an option to choose the right temperature for the light in Kelvins.

Using the mental ray exposure node: With this node you could basically compose directly in maya. You can change the saturation, create a vignette etc. It’s also important to change the gamma correction if you get washed out colors. As computers work mathematically linear and our eyes does not, the pictures rendered out may appear in the wrong color space. So the workflow goes like this; convert textures to linear space, render to linear gamma 1.0 and floating point file format, then convert back into gamma 2.2.

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