Exam questions for 3D Computer Graphics, SP2/2005

Below are listed a number of exam questions. At the exam the student will draw one of this questions and then present in his own way what he feels is relevant to the particular subject matter. For each exam question is listed a few bullet points which are only intended to serve as a guide to what can be presented for each topic. During the presentation it is always an advantage to draw on issues from other questions, for example to present the Phong local illumination model when explaining about e.g. Image-Based Lighting.

(1) Ray tracing

Describe the basic principles in the ray tracing approach to producing computer generated images
Compare the kind of objects that can be handled using ray tracing with the kind of objects that can be handled in polygon based rendering
Compare advantages and disadvantages between ray tracing and polygon based rendering

(2): Local lighting models

Describe the specular and diffuse types of reflection in computer graphics
Discuss the Lambertian diffuse reflection model, and explain how it can be used for simple lighting effects in polygonal and/or ray tracing
Extend the basic ambient and Lambertian diffuse lighting model with an element modelling specular reflection

(3): Polygon based rendering, 2D projections of 3D polygonal objects

Describe the pin hole camera model, and especially the role of the focal length and its influence on perspective projection
Outline the use of matrix formulations in polygon based rendering, including the use of rotations and translations

(4): Visual realism and hidden surface removal

What is the problem behind "hidden surface removal"?
Explain the concepts of backface culling and z-buffering, and compare the two regarding their abilities in solving the hidden surface problem
Outline some techniques for improving the visual realism of images generated using polygon based rendering (e.g., shading, texturing, shadowing)

(5): Mapping techniques

Describe the basic approach in texture mapping and how it complements/supplements shading
Describe the idea behind reflection/environment mapping and relate it to how ray-tracing approaches handle the same effect
Describe the concept of alpha blending for handling semi-transparent objects and give examples of how alpha blending can be used

(6): Shadowing in real-time graphics

Describe the difference between shading and shadowing, and explain the concepts of umbra and penumbra
Describe one or more approaches/algorithms for computing shadows
Relate the real-time approaches to how shadows are computed in ray-tracing

(7): Image-Based Lighting (IBL)

Explain the idea behind IBL
Describe an approach to non-real-time IBL
Describe one or more approaches to real-time IBL

(8): Non-photorealistic rendering (NPR)

Motivate why NPR can be interesting
Describe some NPR shading techniques
Describe some NPR silhouette techniques

(9): Curved surfaces

Explain the idea behind Bezier curves and surfaces (focus on surfaces)
Describe N-patches and explain their advantages