Do Your Poly Models have CG-itis?

Well what is CG-itis? It is a condition where 3D models have a somewhat blocky unnatural look due to razor sharp edges at every turn. Those most at risk are hard surface models such as chairs, desks and John Deere tractors. Is there a cure or a vaccine? Why yes there are, several in fact.

*look to camera 2 and smile*

- Build the model for smoothing: inserting edge loops or splitting where you want to keep definition, the closer the edges, the harder the definition.


- Use the "Bevel" Poly operation, it comes in handy if you're not planning on smoothing the entire model but just want rid yourself of some sharp corners.


- Use the "mia_roundcorners". Its a Mental Ray texture that's plugged into the bump slot of an mia_material. It's "radius" attribute acts like the "offset" attribute of a polygonal bevel operation. Test render away.



And something a tad more complex than a cube on a plane -_-. I used the "insert edge loop" cure in this one.

Fell off the wagon :(

Note to self: I need to get back into 2D, my poor little Intuos is catching dust lol.

Layered Shader [Update]

This post is in addition to my Layering Shaders with Mental Ray post and the focus of that was the mib_color_mix node. A thread on SimplyMaya reminded me that I needed to update this thing.

I found that plugging bare textures into mib_color_mix slots results in weirdo alpha channels in the rendered image, like a strange masking effect on the shader.

This confused me for a while, it seems that Mental Ray uses the top most layer on the mib_color_mix to generate the alpha channel, which in this case is a simple fractal texture. It ignored the fact that there are solid SSS and mia_material shaders beneath it.

I needed to have my fractal spit out a solid alpha, and this is where the "alpha offset" attribute comes into play.



Alpha offset allows me to add black or white value to my texture's alpha in a uniform manner. I set the value to 1. The rendered image will look the same but my little torus will be solid in my alpha mask now because my fractal's alpha is all white.



And of course a value of -1 will have my fractal not even show up in the alpha channel of my render, since since its now black.

Commentor JJJenkins was having problems with alpha offset affecting his color channel and these are the results of my tests.  Forgive my texture, it's the result of 10 seconds in Photoshop lol.

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IES Profiles

IES profiles are files that store information on light shape and intensity so you can mimic these lights accurately in a digital design package plus you get 10 cool points every time you use one.

Random googled images to demonstrate.




You can grab photometric data easily from any lighting manufacturer like General Electric Lighting or Lithonia Lighting just to name a couple. And there is even a free IES viewer, called well....IES Viewer. It was created by Andrey Legotin and it allows you to view all the information associated with the light profiles and there's even a really handy render feature so you can see exactly how the light looks without having to setup a scene in your 3D package just for that yay.

   


Scene setup in Maya: Really simple geometry, walls, ceiling, floor and a few light fixtures. And a camera with a photographic exposure lens shader with a Cm 2 factor of 10000 (have to crank up the value or it'll be too dark) Without the exposure lens shader, you'll get horrifically blown out highlights and hotspots so fast it'll make your head spin. Now on to the lights, I created some point lights and positioned them near my fixtures. Why point lights? They have a special little slot for light profiles in the Mental Ray tab, and clicking that all too familiar checker box will automatically create a light profile node, from there you can browse for the IES file of your choice.


 


Hit render....nothing.... Apparently you have to set a decay rate on the light, I chose quadratic and to keep pace with the light now dying off with distance, the intensity must be increased (don't be shy with the numbers :) and BAM! juicy photometric lights in all their glory hell yeah! 

 
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The Mia_Material_X

    Well, I made my own little shader swatch scene thingy, I had to (I was using spheres prior to this, don't ask, just chalk it up to laziness and back away slowly). Since I'm rendering out swatches, thought I'd write about it, might help a new user, who knows :o).

    The mia_mat_x is one of my favorites, if not my favorite shader, yeah that's right I said it, it's out there now so deal with it. It's a very versatile shader, from glass, to plastic, rock, wood, metal , even the crud stuck in that creepy guy's teeth, it can pretty much do it all. Migrating over from shaders like the Maya Blinn where there are independent channels for qualities like reflectivity and specularity, the mia_mat took a little getting used to since it's a physical shader, good thing the attributes are self explanatory . I tried the whole "use a preset and reverse engineer 'em" method to know what makes that particular "look" tick. Well, that didn't work out too well as I wasn't familiar enough with the shader's default attributes to even know most of what was changed so I decided to poke around 'til I knew what attributes did what.