Rendering/Shading Project 2

Initial File:

http://www.3drender.com/challenges/ Challenge #19: King’s Treasure

Lighting:

For this file I decided to use a Physical Sun and Sky, which one can turn on through the general render options in MentalRay:

However, one can see that just this lighting is extremely dark so we will take advantage of the mia_portal_light light shader, which essentially re-emits the environment in a direction you specify. First, you create area lights (I made one for each window, totaling 4) and size them so that they cover the entire window. Next, in their mental ray attributes, you must turn on the light shape (be sure to check “visible” as well):

After that you can go into the Hypershade window and switch to “Create mental ray node” and go down to the light shaders where you can click to create a mia_portal_light shader. Once you have one in the Work Area, select an area light and find its light shader attribute and middle mouse button drag your portal light shader into the “light shader” label:

Now you do this for each area land and your portal lights are set up. To increase the brightness of the scene, go into the utilities tab of Hypershade and from there you can select your Physical Sky and increase the multiplier value. You can also change the multiplier on your Portal Light shaders (I used 2 different ones for the windows in front of and behind the camera to independently adjust light intensity from each side of the room.

Also you can select the new sun light automatically created and have it emit photons for caustics, etc.

Texturing and Materials:

Since most of the things in this room are metal/glass, there is not much texturing to do. Most of the shading in this one I handled with the mia_material_x mental ray shader, which has many presets available to give you a start. I used this for everything in the scene except for the gemstones, chair wood, and bricks in the background. The best way to learn how to use them is really to look through the presets oneself and play with the settings (which each attribute if you hover over their label gives a surprisingly detailed description in the Maya status bar at the bottom). For a few examples I started with chrome for the sword metal and lamp bronze and copper for gold and worked from there.

For the gemstones I simply refined the Phong_E shader that was assigned to them from the start. From there the main things to change were color and transparency tweaks but most importantly, to turn on refraction in the materials:

Another, more physically accurate approach is to use dielectric_material, found in the mental ray nodes to model the gems. I found it unnecessary for this scene but a good tutorial to look at is:

http://www.3dtotal.com/team/Tutorials/diamond_caustics/diamond_01.php

For the bricks, bag, and tablecloth I used a procedural bump map to create a texture for them. Sample brick network:

Very basic network which works. You might notice no matter how fine you tell your noise/fractal/etc shader to be, it is still too big. That is when you select that place2dTexture node and in its attributes adjust its RepeatUVs (near bottom of the picture):

Finally for the coin, I created a custom bump map. The inital UV layout that comes with the file is fine for this purpose so you can simply take a UV snapshot from the UV Texture Editor window and import it into photoshop and draw or paste a picture with the lines as a reference. My coin:

General Tips and Issues:

I want depth of field!

Look in your camera’s attribute editor and find these attributes:

Now do not turn it on until you are done with everything else. It massively inflates render times.

Everything looks grainy!

Turn up your sampling in your general render options:

This is another thing that will majorly affect render times however. Max samples 2-3 is generally plenty.

Render times are still too long!

You can turn off final gathering and try decreasing reflection refraction trace depth. You’ll generally want higher refractions than reflection depth unless your image has very obvious places where people can see multiple reflections very clearly.

Sample final product: