CS 551/645 Introduction to Computer Graphics Fall 2000

Reminders Evaluate this class by following link from main SEAS web site Participate with UVa student chapter of ACM (Association for Computing Machinery) by attending tonight’s elections after class (6:00) in Olsson’s Basement CS Department is seeking undergraduate TA’s: Check News ox on the CS page or: –

Reminders Colloquium speaker, Jessica Hodgins Carnegie Mellon University Animating with Simulation Olsson 009 at 3:30 on Wednesday

Final Exam Open Book (your choice of text) One page notes (both sides) Material will come from entire semester –Assignments are fair game –No OpenGL or RenderMan questions 3 hours MEC 339 at 7:00 on Monday –Check your s on Monday just in case there is a problem with scheduling the room

Topics Since Midterm Antialiasing Texture Maps Visibility Culling Cells and Portals Quaternions and Curves Parametric Surfaces Hollywood Movies Animation

What’s Different About an Open Book Test? The questions require more thought –I’ll not to write simple questions that demonstrate mastery of index usage For example, the kind of thought that you put into developing your programs Combining techniques in novel ways You want to be comfortable with the vocabulary and the quantitative techniques

Coordinate Systems Right- versus left-handed coordinate systems, two techniques to visualize –Use your thumb and index and middle fingers to for the x-, y-, and z- axes respectively. Arrange them at right angles and they form the coordinate system. –Align your thumb along one axis (say x). As you curl your hand around the x-axis in the direction of your fingertips, you are rotating from the y-axis to the z-axis. Note, the difference between the two: –Position of z-axis –Positive rotation about axis is CCW in RHS –Positive rotation about axis is CW in LFS

Coordinate Systems Cross product definition: –X x Y = Z in RHS –Remember, you are doing it correctly if: You point your thumb along orthogonal vector and you can curl your hand from first vector towards second vector (with along the shortest path between them) –See: le/index2.htmlhttp:// le/index2.html

Confused about OpenGL vs. RenderMan? OpenGL is right-handed RenderMan is left-handed But… –OpenGL default camera points along negative z-axis –RenderMan default camera points along positive z-axis Think some more about how to convert between the two coordinate systems

Intersections Between Geometry How do you compute line-plane intersection? How do you compute the shortest distance between a point and a plane? How do you compute the intersection of a line with a sphere?

Aliasing How are supersampling and mip-mapping related? What are the tradeoffs of the different convolution filters (box, gauss, triangle)? How can you reduce aliasing artifacts during ray tracing?

Texture Maps How do you lay a texture along a bicubic patch? What do you pick for the texture coordinates? How do you arrange six images into a cubic environment map?

Lighting Ray tracing vs. radiosity. –How can we take the best of both? –Render with radiosity first and then a second time with raytracing? Compute intersections, reflections, and color interpolations for ray tracing

Visibility Culling Generate a quad tree for an image Provide examples for z-compression and the errors the finite resolution causes

Quaternions and Curves Formulating an axis-angle Convert from Axis-angle to Quaternion Interpolation of angles using different representations Approximating vs. Interpolating splines Ease of use regarding continuity Rendering curve segments

Surfaces Explain why lighting surfaces more accurate than polygons How does phong shading compare to a more accurate surface representation?

Movies What are challenges to when mixing CG with live action? –Matchmoving –Compositing –Lighting

Animation Compare and contrast –Keyframing –MoCap –Simulation/Procedural How can we combine these to get the best of all worlds?