TECH316 CG Lighting and Rendering

Project Website
4 projects have to be completed within the 10 weeks of the course. These projects are listed in details on this website below. If you are new to this site, please take not more than 5 mins reading the instruction below. It will help you navigate through the content easier.



(A) The index of the content is listed on the right of the page. Click on any to navigate to the page directly. Otherwise scroll down to read more.
(B) The index is not listed totally until you click on the black arrows. Once clicked you will see the full list of the contents under each month when the contents were posted.
(C) Continue to scroll down to read more.

Please enjoy going through the materials in this site, and leave any comments if any by clicking on the "Comments" below each entry.

Thank you.

Project Four - Final Portfolio Piece

The student will work on a project of his/her choice, one that utilizes the lighting techniques from the previous projects. My proposal is to build an entirely CG environment of an abandoned factory floor with a "dead" robot. Every CG model will be built from scratch based on a design that I have done previously on my own time.

See concept drawing of robot, click here. Modeling of the robot was done in 2 weeks while texturing was finished within a week of the project. I used the next 2 weeks before the project due to light, render, and composite the layers in Shake. The rendered layers are: Beauty Pass, Shadow, Occlusion, Specular, and a Matte layer.

Here's the final render after color correction in Shake.

(Click image for larger image)

Matte Layer
One thing I did different for this project was I rendered a Matte layer that acts as a mask layer used in Shake to change specific areas on the final beauty pass without affecting the other portions of the render. This is specifically useful when the scene gets complicated.



Final render on video:

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Project Three - CG Environment and Lighting

The objective of this project is to render a completely 3D environment. A reference image has to be used in this project. Besides, the student will continue to use the technique of rendering in layers and combining these in Shake to achieve the desired result. Through this, the student will acquire a better understanding of lighting and materials, and to see the significance and impact of compositing as part of the lighting and integration process.

Reference Image
I have chosen this as my reference image because I like atmospheric lighting. Light coming in from a direction into a room with no light create a strong key light in the composition that enhances the emotional aspect of the object that is lit.

The visual cues important to this image are strong lighting, composition, and color. The somewhat over saturated color caused by the key light suggests that the mood conveyed is not moody or melancholic, though the shadows do. The light is focused on the wheelchair (object centric lighting) while details are obscured by the light. You might ask, "Why is there an empty wheelchair?" Has the person stood up and walked away and towards the light. The compelling light from the left might mean more.


Lighting Process
The process for this project is similar to Project 2. The scene was rendered in layers and finally composited in Shake. Color correction was done on the final composite to achieve the final look as close to the reference as possible. See process and render below.



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Project Two: Match To Live

This project will give an introduction to setting up a camera, light rig, shadows and reflection of the environment on a simple object to "match" it to that in a photo taken with that object. The process involved choosing a real world object that could be modeled in a short amount of time. Afterwhich, the student would create a series of photos (at least 20) of this object in a variety of settings inclusing outdoor, indoor, daytime and nighttime. The composition would require the object to occupy not more than 25% within the frame, thus leaving room for a CG twin to be included.

Photo references:

(Click on image to view larger pix)

Process
The first step is to make the model of the object chosen, which in this case is a Nivea bottle. Then it will involve UV layout and texturing, and finally a test light to see how the shaders are working with the lights.


Camera Setup will be next. This is done by using "Maya Live". Elements like grid lines, repetitive tiles, and any lines within the reference photo itself, are used as much as possible to correctly setup the camera with the right perspective that matched the reference. The grid view from Maya is an effective tool to make a good approximation. Sometimes fill in geometries have to be created to have better accuracy.



Rendering
Taking into account the positions, color, intensity, transparency and attenuation of the shadows on the original photo, student should attempt to light the scene as close to the reference as possible. Other factors would be reflection from the environment, and other material attributes that affect the lighting.

Rendering is done in passes using rendering layers in Maya. The layers are diffuse, specular, occlusion, shadow and reflection. These layers can be seen as follows:



Compositing
Compositing is done in Shake. See Shake node below. (Click image for larger view).


Final Render and Composite


Comments:
I would lift the bottle cap a little higher just to make the occlusion beneath for obvious. I would also change the environment reflection a little just to match the reference.
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CG Lighting Projects - Project One

The class consists of 4 projects that we have to complete within the 10 weeks of your studies. Project 1 requires students to use 4 different rendering techniques for an "object lighting" of their choices. We would use (1) Raycasting with Dmap shadows, (2) Raytracing with raytraced shadows, (3) Photon mapping or Global illumination, and (4) Final gather for our rendering purposes. With proper use of lighting and composition, we will attempt to create a focus on the objects within a simple scene setup.

There are several factors that determine a good render. The first is the proper use of light to achieve a certain amount of visibility, clarity, and creation of shadows. Composition is as important as lighting. Both add to the aesthetic quality of the final render. Therefore lighting can be object centric or environment centric. Good composition is also about balance and placing the object applying the rule of thirds. Shadow also plays a part in balancing the composition as well.
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Rendering Layers in Maya

Read all about rendering layers in Maya.

a. Rendering layers in Maya I
b. Rendering layers in Maya II

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The Power of Diffuse

Texturing and lighting works together to create more believable CG renders. Here's something that I read about using diffuse. I am getting better understanding of using diffuse channel now... oh yes.. diffuse is the absorption of light.

Read about diffuse.

And there are many other tutorials available too. Here is the link: http://www.noir.org/3dTutorials.html

Purpose of lighting

Just to recap a little:
Light can be used to direct the eyes of the viewer to see the focal point of a frame, create depth, to convey the time of the day, to enhance the mood of the picture, and the reveal a character's personalities.

Ratio of Key to Fill Light Ratio

High Key situation: Lots of soft fill light. Overall scene is quite illuminated. Contrast is low, and scene is usually well lit, and few dark areas. Mood conveyed: light hearted story, comedy, happy, minimize suspense, really nothing left to the imagination, straight forward presentation.
Low Key Situation: Scenes are darkly lit, no fill light, dark overall impression (not milky), light is usually used to direct viewers attention, darkness is to stimulate viewers imagination, good contrast, and evokes a feeling of unrest, and moody. Eg. a film noir is a low key lighting situation.

It really depend on the lighting requirement, and the story that the image/ or moving frame is telling, different lighting conditions will result a complete change in mood and drama.

Technically speaking, creating a believable lighting situation is about getting the shadows to look like those in real life. In 3D lighting, shadows are usually created looking too dark, sharp, flat, without interaction with the environment, lacking contact between the object and the floor, or insufficient variations. The lighting situation in real life is very dynamic and it would take more than a light to make a scene to look "real" or convincing.

According to Jeremy Birn, there are several qualities of light he listed in his book: Softness, intensity, color, throw, direction, animation, and shadow. These play together to convey the mood of a scene, and they can all be controlled quite successfully in Maya.

Maya Light Types

In Maya, there are several light types: ambient, directional, point, spot, and area light. Before going further, the following renders will show their differences and how they function.

Ambient Light
Ambient light is like a light that strikes an object from every direction. The ambient shade attribute controls how the light strike the surface of an object, in this case, the ambient shade is 0.8. Raytraced shadows are supported only. Ambient light flatten the look of the final image, thus it is not ideal while producing photo-realistic results.

Directional Light
Directional light is a light that is emanating from an infinitely great distance, resulting in parallel rays, like the sun, and does not decay. It is useful for lighting vast areas in a scene, and is really suitable to recreate sunlight and moonlight.

Spot Light
The most useful of all light as it illuminates a cone-shaped volume with the source at the tip, and having 2 attributes that control how the edge of the light tapers off.

Point Light
Point light emits omnidirectional light from a single point in space. It is useful for simulating their sources such as candles and incandescent light bulbs.

Area Light
When use effectively, area light can simulate light from fluorescent tubes and panels, or bounce cards.

Volume Light
Volume light is one that is useful to light a specific area. (see maya help for better rendered pix).

Properties of Light

Looking at the photos of the real world is the best way to study the properties and behavior of light. Such understanding will give us a better control over how we light our scene and making it look more natural, and as realistic as possible. There are other properties that govern how "real" a scene can be. Apart from having good textures and modeling, lighting is something that could push a scene from good to great.

These are just some of the examples as good references. Plenty are out there. Start collecting now.

Lighting Design Essentials

Lighting design is the process of creating the look of a shot that you use as a guideline for other shots in a scene to achieve consistency. As a starting point, it is useful to utilize reference materials such as photographs to generate ideas. These show how light bounces, diffuses, and reacts in different situations. Movies are very good source of lighting ideas. Studying still images from films to see where light is coming from or what colors are being used can help you create a more interesting lighting environment for your scene.

Properties of Light
In the real world, light bounces, looks, reacts, and reflects differently and in many ways. The ability to distinguish between different qualities of light is a fundamental requirement of lighting artists in this industry.

In Maya. all light types share 2 common attributes: Color and Intensity.

The intensity attribute control the brightness of a light source. Negative value results in light subtraction, and can diminish light on specific surfaces or create shadow efx without the added render expense of calculating actual shadows.

Color Theory

Color theory can be applied to many aspects, one of them is lighting. Here's a good link to understand color theory:

http://www.colormatters.com/colortheory.html

In the arts of painting, graphic design, and photography, color theory is a body of practical guidance to color mixing and the visual impact of specific color combinations. Although color theory principles first appear in the writings of Alberti (c.1435) and the notebooks of Leonardo da Vinci (c.1490), a tradition of "colory theory" begins in the 18th century, initially within a partisan controversy around Isaac Newton's theory of color (Opticks, 1704) and the nature of so-called primary colors. From there it developed as an independent artistic tradition with only sporadic or superficial reference to colorimetry and vision science.^{[citation needed] - Wikipedia}

Basics of Lighting

As lighting designers, we need to understand the physical and psychological properties of light, and how these will cause an emotional response. Lighting is about creating a picture or frame that describes the mood of the story.

Properties of light: The Physiology of Light
Light is a wave. We response to only a small spectrum of wavelengths between the UV and Infra red. Within these wavelengths will give rise to visible light. Different wavelengths of the light will create different colors to our eyes. For example, red has a longer wavelength, whilst blue has a shorter wavelength.

The visible spectrum of light is show in the diagram below:

According to research, our eyes are more responsive to change of color for green, and the least response to blue. In Maya, the software render attribute window has also taken this response into account. When we look at the contrast threshold setting, a higher value is given to blue, so more variation is given to blue in order to create a pixel of color.

In light, color mixing is additive. As you can see, white light is produced by mixing the colors red, green and blue. In this diagram, RGB are considered primary colors, whilst, yellow, cyan and magenta, are considered secondary colors. Henceforth, white has the value of, 255, 255, 255 in Maya. In real world setting, the colors we see from objects are really the different wavelengths that are absorbed and reflected into our eyes. The objects do not have colors but their colors, in other words, are dependent on their surface properties reflecting and absorbing the light properties.

More information of light can be referenced from:
http://en.wikipedia.org/wiki/Light

A very good resource can be found here. It is an article titled "Pixel Cinematography"that describes the lighting approach to telling a story. Here's the link:

http://www.ics.uci.edu/~ses/teaching/inf290/calahan.pdf

In essence, it decribes how light can be used to direct the eyes of the viewer to see the focal point of a frame, create depth, to convey the time of the day, to enhance the mood of the picture, and the reveal a character's personalities.

The uses of light are more than 1001. A good way to learn to use lighting is to analyze movies with a keen sense of observation. Look out for subtle color changes and how these affect the mood, pace, intensity, and emotional aspect of the story. See how light can change the way you feel about the scene, and the characters. Collect photographs taken professionally and see how light is utilized to create sense of depth and focus.

As a start, watch an animation, eg. "Bugs Life" or "Mr Incredible" and see how lighting is used as a film device.

(Ref: Alias Maya Lighting Video)