CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Applications Computer Graphics. of • Why ? – what can we use it for ? 3D Computer Graphics.

– does it work ? Gordon Watson, • How ?

Edinburgh Virtual Environment Centre. • Where ? –is it going ?

Gordon Watson http://www.edvec.ed.ac.uk 1 Gordon Watson http://www.edvec.ed.ac.uk 2

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Why ? - Applications.

• Aesthetic. – Entertainment: games, cinema, art.

• Visuals can be either ‘realistic’ or abstract. • Can draw inspiration from existing forms of art, e.g cartoon, or can be totally different. • Allows new forms of artistic expression.

Gordon Watson http://www.edvec.ed.ac.uk 3 Gordon Watson http://www.edvec.ed.ac.uk 4

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Applications. Applications.

• Human-Computer interaction. • Visualisation. – Interfaces, Computer-aided-design. – Converting numbers into images. – Hypertext, browsing the web. • Human visual system has greatest bandwidth – Understanding large amounts of data. – 2D interfaces covered in future lecture. – Understand abstract concepts and ideas. – Increasing need for visualisation. – Allow user to interact in 3D with 3D input device. – 3D displays becoming more commonplace. – The real, and unique, power of computer graphics lies in the ability to interact with, and view data in 3D.

Gordon Watson http://www.edvec.ed.ac.uk 5 Gordon Watson http://www.edvec.ed.ac.uk 6

1 CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Problems that require Visualisation. Visualisation of flow.

• Medical – Need to understand nature of 3D structures inside patient. – Data are from 3D X-ray or radiation scanners. • Scientific • Streamlines show flow – Simulations produce huge amounts of data. direction. – Mathematical models are frequently multi-dimensional. • Environment. • Color shows speed. – Need to compare observations about the Earth. – NASA Earth observation system collects over 3Tb per day. • Gives insight into complex interaction between vortices.

Gordon Watson http://www.edvec.ed.ac.uk 7 Gordon Watson http://www.edvec.ed.ac.uk 8

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

‘Virtual Wind Tunnel’ at NASA Ames. Rate of information ‘uptake’

Dataset name and year # points # timesteps size (Mb) Action Units of Information transfer. Tapered Cylinder ’90 131,000 400 1,050 (Source : Silicon Graphics Inc.)

Typing at 10 bytes per second 1 McDonnell Douglas 1,200,000 400 12,800 F-18 ’92 Mouse Operations. 2 Descending delta wing 900,000 1,800 64,800 ’93 Reading 3-40 Bell-Boeing V-22 1,300,000 1,450 140,000 Hearing 60 tiltrotor ’93 Visualisation and Pattern 12,500 Bell-Boeing V-22 5,000,000 1,450 300,000 Recognition tiltrotor ’96

Gordon Watson http://www.edvec.ed.ac.uk 9 Gordon Watson http://www.edvec.ed.ac.uk 10

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Video excerpts. How does computer graphics work?

Artistic Expression. • Computer graphics are a mathematical simulation. • Faux Plafond. – Cosmic Promenade • What needs to be simulated ? – A piece inspired by geometry of world maps. – Shape of 3D objects – 3D geometry. • More later if we have time… – Appearance of surfaces. Visualisation. • How does the surface interact with light? • Volume Visualisation of the Orion Nebula –SDSC. • Shininess, colour, roughness. – Visualising the 3D structure of an object seen from Earth. – Light sources. – Camera with perspective.

Gordon Watson http://www.edvec.ed.ac.uk 11 Gordon Watson http://www.edvec.ed.ac.uk 12

2 CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

The shape of some 3D objects. The appearance of some 3D objects.

Paul Debevec’s Façade (1996). Paul Debevec’s Façade (1996).

Gordon Watson http://www.edvec.ed.ac.uk 13 Gordon Watson http://www.edvec.ed.ac.uk 14

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

The polygon: building block of graphics. A trip down the Graphics Pipeline...

Polygon ( frequently need to be triangles. ) The Scene we’re trying to draw:

So how do we do curves ?? Images courtesy of Picture inc. Vertex Gordon Watson http://www.edvec.ed.ac.uk 15 Gordon Watson http://www.edvec.ed.ac.uk 16

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Wireframe – Technical drawing style view Perspective View from virtual camera

‘Hidden’ lines not removed

Gordon Watson http://www.edvec.ed.ac.uk 17 Gordon Watson http://www.edvec.ed.ac.uk 18

3 CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Hidden lines removed – colours added. Polygons filled with a constant colour.

Gordon Watson http://www.edvec.ed.ac.uk 19 Gordon Watson http://www.edvec.ed.ac.uk 20

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Simple diffuse shading model applied. Smoothly curved surfaces.

Objects have a diffuse ‘matt’ surface.

Objects that should be smooth appear Needs A LOT of faceted. polygons

Gordon Watson http://www.edvec.ed.ac.uk 21 Gordon Watson http://www.edvec.ed.ac.uk 22

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics. Texture mapping – wrapping pictures Add appearance properties - shininess. round objects.

Note, lights are assumed to be ‘distant’.

Gordon Watson http://www.edvec.ed.ac.uk 23 Gordon Watson http://www.edvec.ed.ac.uk 24

4 CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Reflections, shadows and bumpy surfaces. For interaction, graphics have to be fast !

• Requirement for real-time. – Interaction with user requires real-time response. • Also need to model and simulate dynamics of moving objects. • Challenging task to do 25 times a second. – Huge number of sums going on every second ! Difficult to do properly in real- – Much of graphics technology is concerned with time. simplifying and approximations !

Gordon Watson http://www.edvec.ed.ac.uk 25 Gordon Watson http://www.edvec.ed.ac.uk 26

CL1h 2002. Applications of Computer Graphics. CL1h 2002. Applications of Computer Graphics.

Where is it going ? – some trends. Image-based lighting.

The lighting has been ‘captured’ from a real • A trend is convergence of photography and scene graphics. – Millions of flat polygons required to model complex shapes. – Can we get away with fewer if we use images to represent detail ? – Rather than try to model lighting, can we capture it from a real scene ? • Ultimate challenge: synthetic humans. Image from Paul Debevec Gordon Watson http://www.edvec.ed.ac.uk 27 Gordon Watson http://www.edvec.ed.ac.uk 28

CL1h 2002. Applications of Computer Graphics.

Summary of computer graphics.

• Graphics have many applications. – Many aesthetic, but also useful for understanding data. – Very powerful for understanding large, complex 3D datasets. • Graphics are a simulation. – Need to model surface geometry and interaction with light (appearance). – Need to model dynamics and interaction. • Graphics need to be fast. – Need to be able to draw things in ‘real time’. – Very powerful if user can interact with the ‘simulation’.

Gordon Watson http://www.edvec.ed.ac.uk 29

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