Department of Computer Engineering 3D Graphics in Games and Movies

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1 Department of Computer Engineering 3D Graphics in Games and Movies Ulf Assarsson

2 Department of Computer Engineering The screen consists of pixels

3 Department of Computer Engineering 3D-Rendering Objects are often made of triangles x,y,z- coordinate for each vertex Y Why only triangles? X Z

4 Department of Computer Engineering 4D Matrix Multiplication w z y x t s t s t s z z y y x x

5 Y State-of-the-Art Department of Computer Engineering Real-Time Rendering X 2001 Z

6 Department of Computer Engineering Textures One application of texturing is to glue images onto geometrical object + =

7 Department of Computer Engineering Texturing: Glue images onto geometrical objects Purpose: more realism, and this is a cheap way to do it + =

8 Department of Computer Engineering Light computation per triangle light

9 Environment mapping Department of Computer Engineering

10 Department of Computer Engineering Bump mapping by Blinn in 1978 Inexpensive way of simulating wrinkles and bumps on geometry Too expensive to model these geometrically geometry + = Bump map Stores heights: can derive normals Bump mapped geometry

11 Particle System Department of Computer Engineering Particles

12 Image courtesy of BioWare Department of Computer Engineering Shadows More realism and atmosphere Neverwinter Nights

13 Department of Computer Engineering Shadows play an important role for realism

14 Shadow Maps Point not represented in shadow map (point is behind box) Camera s view Light s view (Shadow Map) Tutorial Shadow Algorithms for Real-time Rendering 14

15 Beyond Programmable Shading 15

16 Real time hair rendering Two main challenges Self shadowing Standard shadowing techniques fail Shadow Maps => aliasing at sillhouette edges Shadow Volumes => overdraw proportional to the number of sillhouette edges Hair is ALL sillhouette edges Neither technique handles transparency Transparency Each strand should contribute very little to a pixel (~1%) Hair strands are actually refractive and at least some transparency effect is required Alpha blending works very well to handle this Beyond Programmable Shading 16

17 Draw transparent objects back-to-front Painter s algorithm: sort transparent primitives and render back-to-front. E.g. 30% transparency means objects behind show through by 30%. Beyond Programmable Shading 17

18 Importance of Shadows Images from: Tom Lokovic and Erich Veach, Deep Shadow Maps, pp , Siggraph Beyond Programmable Shading 18

19 Importance of Transparency Hair is sub-pixel sized and transparent, alpha blending is absolutely necessary Without alpha blending With alpha blending Beyond Programmable Shading 19

20 Real time hair rendering The two problems are quite similar For shadows, we want to know how much the hair fragments, in front, blocks the light - Can be solved by sorting For transparency, we need the hair strands sorted in back-tofront order Beyond Programmable Shading 20

21 Results About half a million line segments rendered with 256 Opacity Map slices and approximate alpha sorting at 70 fps (GTX480) Beyond Programmable Shading 21

22 Beyond Programmable Shading 22 Ulf Assarsson 2004

23 Results 46 fps using 400k hair strands (1.8M line segments) Beyond Programmable Shading 23

24 Volumetric Shadows Single Scattering in Participating Media Beyond Programmable Shading 24

25 With courtesy of Illuminate Labs Department of Computer Engineering Photorealism

26 Department of Computer Engineering How making objects appear as belonging to a certain environment? Lamps illuminating our object Photograph of full environment

27 Department of Computer Engineering

28 Department of Computer Engineering

29 Department of Computer Engineering

30 Department of Computer Engineering With courtesy of Dorna Sports: Moto GP2

31 Half Life 2 Department of Computer Engineering

32 Department of Computer Engineering Spherical Harmonics The general solution to Laplace's equation is a linear combination of the spherical harmonic functions multiplied by the coefficients.

33 Department of Computer Engineering Subsurface Scattering Photons go into the surface, and bounce around Standard way Subsurface scattering

34 NVIDIA Skin Department of Computer Engineering

35 Vill du veta mer? Department of Computer Engineering Välkommen till TDA361 Computer Graphics Lp2, 2012