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GA2211: Hard Surface and Organic Modeling This course covers advanced modeling techniques used for building organic and hard surface objects and environments.

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Week 4: Creating a Studio Rendering Setup

 

-----Click here to download a PDF for the exact process used-----

For a good looking rendering, I used the setup shown below to generate my lighting.

---Spotlight 1 is my key light, the most intense light source and casting both Shadows and Photons into the scene
---Pointlight 1 is my back/rim light. Specifically, it is behind the behind the head from the view of the camera. Without a light behind the skin, there will be no rays to beam through from the back, and the effects of backscatter will be imperceptible.
--- Pointlight 2 is a fill light from underneath.
--- Arealight 1 is a fill light from the stage left (character right) which is being used to soften up the dark side of image.
---- nurbsSphere1 was cut in half and used as a backdrop for the shot. Curved walls mean that you don't get harsh shadow creases where the floor meets the wall meets the ceiling.
--- pSphere1 is a full sphere set to render as single sided. A surface shader has been applied with a panoramic photo. This sphere is set to be visible only in reflections and provides detail for reflections from a photographic enviornment
--- Final Gather, Global Illumination, and Caustics have all be enabled for this demo.

I use this enviornment to render out all sorts of elements in my own work. It gives me a soft fill and shadows, a floor with a smooth transition to the backwall, and a bright primary source light.

 

 

This video covers an advanced setup for this 3pt lighting techinique:

Advanced lighting 03 - studio lighting from CG Bootcamp on Vimeo.

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Rendering clean wireframes with the Mental Ray Contour Shader
Click on image below for tutorial:

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Rendering Ambient Occlusion (AO):

When two objects are close to each other, less light reaches the areas between the two of them.
We can render this physically in Maya as so:

Using the mib_amb_occlusion texture under the mental ray nodes in the hypershade, we can connect the texture to the color and ambient color channels. By adjusting some settings, we get a render where light is occluded out of these areas.

BAKING AO TUTORIAL... CLICK HERE:

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Types of Lights:

spot lights- A spot light has a cone of influence in a specific direction. This is controlled by the Cone Angle attribute which is measured in degrees from edge to edge. The Spot Light also has Decay, Dropoff, and Penumbra. Great for lamps, grazing accent lights, and dramatic effects, as well as for producing light fog.

directional lights-The Purpose of a directional light is to simulate a distant light source, such as the sun, where light rays are coherent and parallel. This type of light will produce a harsher, more intense quality of light with harder edges and no subtle changes in surface shading becasue of its parallel rays with no decay. Directional Lights are not very expensive to render because the angle is consitent for all rays and decay is not computed. It also cannot simulate light fog.

point lights-The Point Light emits rays from a single point outwards in all directions. It can accurately simulate a lightbulb or candle as a result. Point lights DO have decay and will typically produce more subtle, yet richer shading on surfaces. THIS IS LIGHT EMITING FROM 1 DIMENSION IN 3D SPACE.

area lights-Unlike point, directional, and spot lights, area lights are far more naturalistic in that all light sources must exisit in multiple planes of 3d space. Thusly it is a less abstract shading model, but also more expensive to render. An are light reflects the size and orientation of the light. They are great for straight, long, specular, highlights. For soft lighting across a scene. And for Realistic shadows that vary from hard to soft. All area lights have built-in quadratic decay (see below). THEY DO NOT WORK WELL WITH DMAP SHADOWS. THIS IS LIGHT EMITING FROM 2 DIMENSIONS IN 3D SPACE.

volume lights-This is the most physically accurate definition for a light, but it usually far to costly for us to render with. The Volume light will illuminate objects within given volume. THIS IS LIGHT EXSITING IN 3 DIMENSIONS OF 3D SPACE.

ambient lights-An ambient light is a non-directional light that can be used in low intensities to simulate the diffused, scattered or reflected light you see in real life. When doing more advanced rendering, global illumination simulatios are used instead. The ambient light has an ambient shade characteristic as well.

the default light-If there is no light in a scen, maya will create a directional light when the scene is rendered. This light is parented to the rendered camera and illumates the scene regarless f where the camera is facing. After the render is complete, Maya removes the default light from the scene

 

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Light Properties:

Intensity-Intensitycan be defined as the actual or compartive brightness of the light. It can be modified with the slider, or texture mapped. We will look at texturing intensity with ripple patterns to fake caustic lighting effects in underwater simulations in the upcomng weeks.
Color ->View the Color Temperature chart below, indicating relative color values for certain light sources:


The color the light can also be mapped.

Dropoff (spot light specific)- is similar to decay except for that its function is to cause the light to diminish in intensity perpendicular to the light axis instead of along the light axis.

Penumbra (spot light specific)- The Penumbra is the area at the edge of a spot light where the light diminishes in intensity. The larger the radius of the penumbra, the softer the circle of light projected by a spot light will be.

Ambient shade (ambient light specific)- This attribute allows you to specify how much light comes frm the source. I set to 0, it applies evenly across the whole scene, where as a value of 1 a the other extreme causes there to be direction associated with that ambient light, based on it's position.

Decay rate (for point,spot and area)- Decay refers to how light diminishes with distance. In maya, it is possible to alter the rate of decay in four sepeate ways: No Decay, Linear, Quadratic, and Cubic

No Decay	Light will contine forever; will reach all objects in the scene.
Linear	Liht intensity decreases in direct proportion to distance. Longer to render, but diminishes less than in nature.
Quadratic	This is how light decays in real life. (I=1/d*d). Longer to render still.
Cubic	Light decays faster than real life. (I=1/d*d*d). Longest to render.

 

Raytrace Shadows are the natural simulation of shadowing effects in 3d. Raytrace Shadows are produced on a ground surface when light in the form of a ray, being casted from a light source such as a point light or spot light or directional light (etc...), is occluded out by an intercepting object. As the rays are blocked, no light can reach the ground plane, and thusly a shadow is produced. See Image 1:


By Default, Raytrace Shadows produce very hard edges. This is unnatural to what we see in real life (View the floor in Gothic Cathedral Image above). Since physically, Light can exhibit both Photonic (particle) and Wave like properties, we have to take this into consideration when simulating raytrace effects. By their very nature, anything exhibitng the properties of a wave, (and all quanta materials will), can have those waves reflected, refracted, and interferred with. These principles are exactly behind the theories of Global Illumination, Radiosity, and Refractivity in Media Denser than air, which we will look at throughout the course.

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Creating Cameras:
I will create 3 cameras for 3 render angles:

1- I will create an out of the room camera from 3/4 above
2- I wll create 2 in-room cameras, with wide angles

To create a Camera, go to Create-Cameras-Camera



You can look through the camera by going to Panels-Perspective-Camera1 (or whatever the camera's name is)
You can then frame the render angle by going to View-Camera Settings-Resolution gate.
Now, whatever resolution you have enabled in the render settings (in this case 1024x768) will be what gets projected in the camera view.


Once inside the room with camera, you may find it hard to see anything. I suggest changing the camera's Angle of View by selecting the camera (View-Select Camera) and entering the attribute editor. I upped my angle of view here to 100, widing out the angle and letting me see more of the room. I then named my camera and duplicated it to place 2 more version in other spots (which we will see later).

While in the attribute editor, I also like to change the Background color of the camera. Scroll down to the Enviornment section and open up that rollout. Set your Background color to white for now. It will look odd if you have light coming though a window, but the outside is as black as night.

For each camera, I like to lock down the camera itself once I have it in the correct spot so that I don't accidently move it. To do this, I open the channel box, then drag a selection over all of the channels and choose lock selected from the RMB marking menu.

 

 

Lighting a Room:
I like to create my lights in 5 steps. For this render setup I am using Mental Ray on Production quality with a render size of 1024x768

Before Rendering, if you had previously set the walls of your room as Single sided, now is a good time to turn back on double sided, or your shadows will not cast correctly.


-First I add in the direct light of the Sun using a direction light and enabling raytrace shadows on this light. I set a yellow color and an intensity at 1 or above. I also enalbed raytrace shadows.


Here are my Raytrace Shadow Settings:


Here is a render, as is, from my first camera angle:







-Then I add in a fill light using an ambient light with amibent shade. I place this near the window-ish, and set a low intensity. I NEVER cast shadows with and ambient light, they exist just for fill.

Now when I render, I can start to see things in the room a bit better, but we're not there yet.

 

-Next, I add point lights in the places where I have light fixtures. In this case, I add 4 lights, 1 for each of the 2 lamps, and 1 for each light bulb in the ceiling fixture, as you can see in this diagram from a top-down view. I set a Decay Rate of Linear to allow some diminishing of intensity over distance, and to compensate for that I up my intensity by a huge margin.

Now I am starting to get some life into the room. Notice though how low the contrast is since I am missing my contact shadows (which AO will provide later)

-Next, I add spot lights for theatrical empahsis on areas where I feel need a little more "oomph". Her I add a yellow-ish spot light facing the couch. I also add a blue-ish spot light grazing down the far hallway.

This starts to bring even more life into the space.

-Finally, I tack on my ambient occlusion pass.
----------- I select all of my geo (but not the lights) and create a new render layer.
----------- I name this layer AO.
----------- I then RMB-click and choose attributes.
----------- At the top, there is a presets button, click-hold and choose occlusion from the marking menu
----------- This creates a surface shader with an occlusion texture in the color slot. Click on the "go to output connections" button at the right end of the color slider
----------- This takes you to the occlusion texture. Edit the parameters similar to what you see below. Change the Max Distance to grow or shrink the size of the contact shadow.
----------- Under the Render Layers section, set the new layer as Multiply
----------- Make sure the red X is turned off on the Master Layer
----------- Set your Render Options to Render All Layers (composite only)


Now when I render I get nice, deep contact shadows! You will notice in the final render shown here, that your plant won't render AO with transparency correctly. This can be fixed, but it is beyond the scope of this course. If you'd like to go for fixing it, you'll have to learn a little more on your own about linking up materials in the hypershade, or just take Advanced Texturing and Lighting with me, and I'll be happy to guide you then!