Problems that require Visualisation. Visualisation of flow. - PDF document

Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. Computer Graphics. Applications Applications of of • Why ? – what can we use it for ? 3D Computer Graphics. 3D Computer Graphics. • How ? – does it work ? Gordon Watson, • Where ? – i s it going ? Edinburgh Virtual Environment Centre. Gordon Watson http://www.edvec.ed.ac.uk 1 Gordon Watson http://www.edvec.ed.ac.uk 2 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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. – Understand abstract concepts and ideas. – 2D interfaces covered in future lecture. – Increasing need for visualisation. – Allow user to interact in 3D with 3D input device. – The real, and unique, power of computer graphics lies – 3D displays becoming more commonplace. 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

Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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. • Gives insight into complex – NASA Earth observation system collects over 3Tb per day. interaction between vortices. Gordon Watson http://www.edvec.ed.ac.uk 7 Gordon Watson http://www.edvec.ed.ac.uk 8 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. ‘Virtual Wind Tunnel’ at NASA Ames. Rate of information ‘uptake’ Action Units of Information Dataset name and year # points # timesteps size (Mb) transfer. (Source : Silicon Graphics Inc.) Tapered Cylinder ’90 131,000 400 1,050 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 Reading 3-40 ’93 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 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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? • Shininess, colour, roughness. • Volume Visualisation of the Orion Nebula – SDSC. – Light sources. – Visualising the 3D structure of an object seen from Earth . – Camera with perspective. Gordon Watson http://www.edvec.ed.ac.uk 11 Gordon Watson http://www.edvec.ed.ac.uk 12

Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. The polygon: building block of graphics. A trip down the Graphics Pipeline... 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 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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

Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. Simple diffuse shading model applied. Smoothly curved surfaces. Objects have a diffuse ‘matt’ surface. Objects that should be Needs A LOT of smooth appear faceted. polygons Gordon Watson http://www.edvec.ed.ac.uk 21 Gordon Watson http://www.edvec.ed.ac.uk 22 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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

Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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 – Much of graphics technology is concerned with properly in real- simplifying and approximations ! time. Gordon Watson http://www.edvec.ed.ac.uk 25 Gordon Watson http://www.edvec.ed.ac.uk 26 Applications of Computer Graphics. Applications of Computer Graphics. CL1h 2002. CL1h 2002. 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 Applications of Computer Graphics. CL1h 2002. 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