Level of Detail Management for Games David Luebke University of Virginia Introduction, Overview

Course Introduction l Level of detail (LOD) methods are a crucial tool for game developers –Manage complexity of 3D scenes –Trade off fidelity for performance –Tune game for different platforms l This course will cover advanced issues in LOD for games

Course Prerequisites l We assume –Knowledge of the basic LOD concept –Experience with interactive graphics l Target audience: game developers wishing to –become sophisticated LOD users –write or modify code to create LODs –gain a broader perspective on the LOD field

Course Topics l Generation LOD frameworks & creation l Application Applying LOD in the game setting l Theory Measuring & controlling fidelity

Speakers In Order of Appearance l David Luebke, University of Virginia l Amitabh Varshney, University of Maryland l Jon Cohen, Johns Hopkins University l Martin Reddy, Pixar Animation Studios l Ben Watson, Northwestern University l Rob Huebner, Nihilistic Software

Course History l Courses at IEEE VR and SIGGRAPH l Book – Level of Detail for 3D Graphics –Coupon l Tried to distill a –Practical overview for game developers –Useful introduction to relevant theory –Introduction to potentially useful academic research

Course Schedule 10 LuebkeWelcome, Introductions 10:15 VarshneyGenerating LODs: Algorithms Operators and algorithms for simplification 11 Break 11:15 CohenGenerating LODs: Error Measuring error to guide simplification & LOD 12 ReddyRuntime LOD Management Balancing cost, benefit, and rendering budget 12:30 Lunch

Course Schedule 2 WatsonGenerating LODs: Topics Artist-assisted and out-of-core simplification 3 Luebke,View-Dependent LOD Varshney Higher fidelity per polygon…at a cost Varshney Higher fidelity per polygon…at a cost 4 Break 4:15 Reddy Terrain Simplification Algorithms for an important special case 5 Huebner Game LOD: Geometric LOD Platform challenges, LOD in game production 5:30 Huebner Game LOD: Beyond Geometry Textured imposters, shader LOD, and more

LOD Course notes l Some slides are available on GDC CD l All slides will be available at lodbook.com –Web site for our book n “Level of Detail for 3D Graphics” n 20% coupon available from speakers –Lots of other info available at the web site! n Publicly available LOD source code n Links to commercial tools, sample models n Full bibliography

Level of Detail: The Basic Idea l In its most common form: –Simplify the amount of detail used to render small or distant objects –Known as Level of Detail or LOD n A.k.a. polygonal simplification, geometric simplification, mesh reduction, decimation, multiresolution modeling, …

Courtesy Stanford 3D Scanning Repository 69,451 polys2,502 polys251 polys76 polys Level of Detail: Traditional Approach l Create l Create levels of detail (LODs) of objects:

l Distant objects use coarser LODs: Level of Detail: Traditional Approach

Discrete Level of Detail l Traditional LOD in a nutshell: –Create LODs for each object separately, using artists or a software preprocess –At run-time, pick each object’s LOD according to object distance or similar criterion l Other approaches are possible –Continuous LOD, view-dependent LOD, terrain LOD, imposters, shader LOD, etc. –We will discuss these throughout the tutorial

Next: Generating LODs l Next topics: – Amitabh will discuss algorithms and operators for creating simple LODs from complex models –Jon will discuss error metrics to guide and evaluate LOD creation