# Advanced Computer Graphics - SS 2015

This course will introduce students to advanced and more complex methods and techniques of computer graphics. Some of the topics that were touched upon in the Bachelor course "Computer graphics" will be covered in more depth. In addition, more topics will be covered that were not touched upon in the Bachelor's course. This apporach will both broaden and deepen students knowledge about the field of computer graphics.

This course is for you, if you want to acquire ...

- Knowledge of advanced and more complex methods and techniques of computer graphics.
- Mastering of some of the topics that were already touched upon in the basic computer graphics course, by expanding them in greater depth.
- Ability to follow the current research literature on those topics.
- Skills to implement complex techniques in those areas.
- Knowledge of the principles of photorealistic image generation.
- Larger overview over the amazing wealth of topics and research questions in computer graphics,

There are no formal prerequisites, but some degree of the following skills are desirable:

- A little bit of experience with C/C++ ; note that we will need just "C with classes" during this course.
- Knowledge of the material of the Bachelor course "Computer graphics" (if you didn't manage to attend that course, you can easily recap that material for yourself).
- Algorithmic thinking (and, hopefully, some pleasure when thinking about algorithms)

Some of the envisioned topics (these can change during the semester):

- Data structures and the theory of boundary representations (meshes);
- Advanced methods for texturing (more realistic ;
- Generalized barycentric coordinates and parameterization of meshes;
- Advanced shader programming (special effects);
- Culling techniques (real-time rendering);
- Ray-tracing (photo-realistic images);
- Alternative object representations (modeling);
- Anti-aliasing (improvement of quality)

### News

### Folien

The following table contains the topics and the accompanying slides (it will be filled step-by-step).Week | Topics |
---|---|

1. |
Organization; Ray-tracing 1: principle, camera models, lighting model, secondary rays, refraction, Fresnel terms, attenuation, dispersion, intersection ray-polygon, intersection ray-triangle, ray-box, ray-sphere |

2. |
Ray-tracing 2: ray-tracing height fields, numerical robustness, distribution ray-tracing,
anti-aliasing, soft shadows, glossy-matte reflection, depth-of-field,
motion blur. Exercise meeting (discussion of solutions of last week's exercise, presentation of the new assignments) |

3. |
Object representations: implicit surfaces, root finding with Laguerre's method,
quadrics, metaballs, generalizations,
polygonization of implicit surfaces using Marching cubes,
instancing, constructive solid geometry, fractals. Acceleration data structures 1: taxonomy, light buffer, beam and cone tracing, 3D grids, mailbox technique. |

4. |
Lab meeting (discussion of solutions of last week's exercise,
presentation of the new assignments). Acceleration data structures 2: traversal and storage, recursive grid, hierarchical uniform grid, proximity clouds, octree, 5D ray octree, kd-trees, kd-tree traversal, construction, surface area heuristic (SAH), efficient storage of kd-trees. |

5. | Acceleration data structures 3: bounding volumes, bounding volume hierarchies, BVH traversal, construction of BVHs, median cut heuristic, plane sweep along principal axis with SAH |

6. | Advanced Shader Techniques 1: procedural textures in the shader, value noise for procedural textures, gradient noise |

7. |
Advanced Shader Techniques 2:
refractive objects,
the geometry shader, examples, rendering furry/fluffy objects with shells and fins,
rendering silhouettes. Tone Mapping: HDR imaging, image histograms, histogram stretching, histogram equalization, tone reproduction by Ward, the Weber-Fechner law, perceptually-based tone mapping, generating histograms on the GPU |

8. | Advanced texturing methods: seams, texture atlas, cube maps, polycube maps, concept of environment mapping, spherical environment mapping, cube env mapping, parallax mapping, view-dependent displacement mapping, VDM with self-shadowing |

9. | Culling: Bottlenecks in the rendering pipeline, kinds of culling, backface culling, normal masks, clustered backface culling, hierarchical clustered backface culling, view frustum culling, hierarchical view frustum culling, occlusion culling, batched queries, naive wait-and-draw algorithm, multiqueries, coherent hierarchical culling (CHC++), portal culling, detail culling |

10. |
Orienting meshes consistently; Boundary Representations 1: definitions, orientability, 2-manifold, homeomorphism, OBJ file format, indexed face set, doubly-connected edge list (half-edge data structure), mesh traversals using a a DCEL, limitations of DCEL |

11. | Boundary Representations 2: Euler equation, Platonic solids, Euler characteristic. Striping/Stripification: concepts, NP-completeness, SGI algorithm, FTSG algorithm |

12. | Generalized Barycentric Coordinates 1: definition, interpolation property, general construction scheme and properties, mean value coordinates |

13. |
Generalized Barycentric Coordinates 2:
extension to non-convex polygons, applications, image warping,
mesh morphing. Parameterization: general approach, condition and proof of unique solution, concrete parameterizations. Mesh smoothing: Laplacian smoothing, extension, global Laplacian smoothing. |

14. |
Procedural modeling: seashells, fractal terrain modeling,
terrain modelling using fault lines, L-systems
(D0L, parametric, stochastic), L-system for modeling rocks. Anti-Aliasing: artefacts from aliasing, sampling theorem, supersampling, subpixel masks by LUT, different sampling patterns (RGSS, Quinkunx, Flipquad). |

You can download some of the shaders that were discussed in class, plus some some very simple ones (discussed in the Bachelor course).

### Textbooks

The following textbooks can help review the material covered in class:- Andrew Glassner (ed.):
*An Introduction to Ray Tracing*; Morgan Kaufman - Peter Shirley:
*Realistic Ray Tracing*; AK Peters. - Foley, van Dam, Feiner, Hughes:
*Computer Graphics -- Principles and Practice*; Addison Wesley. - Tomas Akenine-Möller, Eric Haines:
*Real-Time Rendering*; AK Peters. - Matt Pharr, Greg Humpfreys:
*Physically-Based Rendering*; Elsevier. - Alan Watt, Mark Watt:
*Advanced Animation and Rendering Techniques*. Addison-Wesley - Online Literature, see below

Please note that the course is *not* based on one single textbook!
Some topics might even not be covered in any current textbook!
So, I'd suggest you first look at the books in the library before purchasing a copy.

If you plan on buying one of these books, you might want to consider buying a used copy -- they can often be purchased for a fraction of the price of a new one. Two good internet used book shops are Abebooks and BookButler.

### Grades and Points achieved by the Assignments

For taking part in a so-called "Fachgespräch" (mini oral exam), you need a grade from the assignments >= 4.0 . You can get this by doing the exercises (assignments). You need at least 30% in total of all points of all asignments to achieve a grade of 4.0 .

### Some Additional Literature You Might Want to Read for Deeper Insights

- On Raytracing:
- An animated video explaining the rendering equation by Matthias Parchettka; it's only in German (ist ein wenig albern, aber vielleicht trotzdem hilfreich; source).
- Siggraph course notes on implicit surfaces, 1996.
- Siggraph course notes on interactive ray-tracing, 2006.
- Alex Ryer: Light Measurement Book (source); explains a lot of the principles of light sources, light perception, and light transportation.

- Literature on advanced texturing techniques:
- The tutorial OpenGL cube map texturing by NVIDIA, 1999.
- Siggraph course notes lighting and shading techniques for interactive applications , 1999 (chapters 6, 10, and 11).

- On GLSL, shader programming, and GPGPU programming:
- Einen Link zu unserem Shader Maker (und viele Shader-Beispiele) finden Sie hier.
- A tutorial on shader programming in GLSL (Source: Lighthouse 3D).
- Ein GLSL Quick Reference Guide (Quelle).
- Die offizielle GLSL Spezifikation (falls man etwas nochmal ganz genau nachschlagen muß).
- Die OpenGL 4.1 Reference Pages (sehr praktisch zum schnellen Nachschlagen).
- Dominik Goeddeke's GPGPU::Basic Math Tutorial, in dem die einfachen Prinzipien anhand der "saxpy"-Operation erklärt werden (Quelle).
- Eine leicht verständliche Einführung in Framebuffer Objects von gamedev.net (Rob Jones) (Quelle).

- An easy introduction to simplex noise by Stefan Gustavson (source).
- A fairly comprehensive explanation of Spherical, Cubic, and Parabolic Environment Mappings by Paul Zimmons.
- On Culling:
- Hansong Zhang, Kenneth E. Hoff III: Fast Backface Culling Using Normal Masks
- Andreas Johannsen, Michael B. Carter: Clustered Backface Culling
- Ulf Assarsson and Tomas Möller: Optimized View Frustum Culling Algorithms for Bounding Boxes
- Lighthouse 3D: View Frustum Culling Tutorial

- Literature complementing the chapter on boundary representations:
- A paper on array-based mesh data structures (for our course, only the first part is relevant)
- A nice tutorial on the DCEL data structure by Ryan Holmes (source)
- A tutorial on
specification, representation, and construction of non-manifold geometric structures
(this is only partially relevant for our course, but it can serve as an outlook on
how to extend the concepts into
*n*-dimensional geometry) - Two essays on the Euler characteristic: one by Edward Early (source), and one by Sudesh Kalyanswamy (source), the latter being more geared towards graphs, but still relevant in computer graphics, too.
- A simple proof of the Jordan Curve Theorem for the important class of polygons (source)
- Similar to regular polyhedra, one can even define Infinite Regular Polyhedra, and, here too, the genus plays a very important characterizing role (source)

- Literature on generalized barycentric coordinates:
- Hormann & Floater: Mean Value Coordinates for Arbitrary Planar Polygons
- Surazhsky & Gotsman: Intrinsic Morphing of Compatible Triangulations
- Floater: Mean Value Coordinates

- The SIGGRAPH 2007 course notes on Mesh Parameterization by Kai Hormann, Bruno Levy, and Alla Sheffer. (Source)
- Literature and links on L-systems:
- The wonderful book The Algorithmic Beauty of Plants by Przemyslaw Prusinkiewicz and Aristid Lindenmayer, 2004. (Source)
- Arbaro is a free software to generate tree models for povray.

- A tutorial on the PCA by Prof. Laurenz Wiskott, 2004. (Source)

Last modified: Thu Jul 16 10:34:06 CEST 2015