Overall teaching objectives:
Teach students how to produce acurate images of 3D scenes by shooting a ray from the eye through each pixel adn by estimating the light reflected in the direction of the eye by the visible surface that the ray hits. This exercise includes learning how to set up the view parameters, how to compute the intersection of the visible surface for each ray, how to verify whether the visible point is illuminated by each light source, and how to compute the color reflected by the surface towards the viewer. The students should understand the computational costs and imitations of this ray-casting approach and know how to improve the quality of the produced image through ray-tracing and/or through radiosity. The students need to understand the concept of the BRDF and its use for rendering. Finally, they need to understand the property of lambertian surfaces and why it appears to have the same color from all directions eventough the intensity of the reflected light varies with the the cosine of the angle between the surface normal and the viewing direction.
Motivation and relation to other modules:
What students should know:
How to compute the pixels on the virtual model of the screen from the view parameters
How to compute the visible surface for each ray, for a scene with spheres and triangles
How to compute the direction of the reflected ray
Meaning of BRDF and its use for computing the reflected color.
BRDF for perfect Lambertian and Specular surfaces.
How to test whether the point is lit by a point light source
How to approxiamte area light sources
Why raycsating is not satisfactory
The benefits, costs, and limitations of raytracing
The benefits, costs, and limitations of radiosity
Lecture slides: jarek
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Examples of exam questions:
What is BRDF and how is it used in ray-tracing.
What is the difference between ray-tracing and ray-casting.
What is wrong with a ray-traced picture: what effects are not correctly depicted?
Explain how to improve ray-casting to add shadows for point light-sources. State why the resulting images will still be wrong.
Provide the overall algorithm for ray-tracing and estimate its computational complexity.
What problem is solved by casting secondary rays? What kind of reflections are missed?
What problem is solved through radiosity? What kind of reflections are missed?
What is a Lambertian surface? Give examples.
The amount of light emitted in direction V by a point on a smooth Lambertian surface with normal N is proportional to the dot-product of N with L. Explain why the intensity of light reflected by a Lambertian surface appears to be independent of orientation.