Business and Computing Deanery 3D Modelling Tools Week 16 – Lighting

3D Modelling Tools 2 This week Lecture Lighting Rendering Computer graphics Standard lights Shadows 3DS Max 7 Bible Chapter 27

3D Modelling Tools 3 Rendering Rendering "fills in" geometry with color, shadow, lighting effects, etc. Converts three dimensional scenes to two dimensional screens by following rays of light from the eye of the observer to a light source

3D Modelling Tools 4 Photorealistic rendering “In computer graphics, photorealistic rendering attempts to make artificial images of simulated 3d environments that look just like the real world.” Reynolds (2003) Where is it used? What are the implications? Hardware Time Interactivity

3D Modelling Tools 5 Realtime rendering Relies on graphics cards with 3D hardware accelerators Where is it used? What are the implications? Hardware? Time Interactivity

3D Modelling Tools 6 Rendering techniques 1 Ray casting Renders the scene as observed from a specific point-of-view based only on geometry using very basic optical laws of reflection intensity Does not render accurately reflections, refractions, or the natural fall off of shadows

3D Modelling Tools 7 Rendering techniques 2 Ray tracing Similar to ray casting, but employs more advanced optical simulation Can use multiple rays Traced through a number of sequential 'bounces‘ Realistic reflections and shadows Too slow to consider for realtime 3ds max v7

3D Modelling Tools 8 Rendering techniques 3 Radiosity Uses finite element mathematics to simulate diffuse spreading of light from surfaces Rendering technology that realistically simulates the way in which light interacts in an environment 3ds max v7

3D Modelling Tools 9 Comparison Lighting Algorithm AdvantagesDisadvantages Ray-Tracing Accurately renders direct illumination, shadows, specular reflections, and transparency effects. Memory Efficient Computationally expensive. The time required to produce an image is greatly affected by the number of light sources. Process must be repeated for each view (view dependent). Doesn’t account for diffuse interreflections. Radiosity Calculates diffuse interreflections between surfaces. Provides view independent solutions for fast display of arbitrary views. Offers immediate visual results. 3D mesh requires more memory than the original surfaces. Surface sampling algorithm is more susceptible to imaging artifacts than ray-tracing. Doesn’t account for specular reflections or transparency effects. 3ds max v7

3D Modelling Tools 10 Render farms Rendering networks are sometimes called “render farms.” In the software, one computer is set up as the network Manager. The Manager "farms out" or distributes the work to rendering Servers. Pixar have created Renderman 10 years ago it took 6 hours to render one frame How many today? Use render farms

3D Modelling Tools 11 Lighting - realtime v. photorealistic Compare lighting OpenGL - max 8 lights Photorealistic – 10 lights per character Convergence of realtime and photorealistic Realtime is now used to plan real movies Used extensively in games

3D Modelling Tools 12 Internal or 3 rd party Traditional The CG production pipeline Story Art Set design Layout Animation Shading Modelling Rendering Lighting Simulation Effects Film Commercial Editorial

3D Modelling Tools 13 Concepts Light has warmth (yellowish) or coolness (bluish) Intensity Angle if incidence Radiosity Light reflecting from an object Attenuation Light becomes weaker with distance 3ds max v7

3D Modelling Tools 14 Lighting basics Three main sources of lighting in classic photography Key Fill Backlight Concepts apply to 3D programs, plus Ambient light

3D Modelling Tools 15 Getting it right 3ds max v7

3D Modelling Tools 16 Key light Outdoors The sun Indoors Major window Main electric light Flash on a camera Spot light on a stage

3D Modelling Tools 17 Fill and key lights Fills in the dark shadows cast by the key light Outdoors may be created artificially Indoors from secondary lights Distant window Light fitting Softens shadows 3ds max v7

3D Modelling Tools 18 Backlight Situated behind the subject Separates the foreground from the background Can make the scene more three- dimensional

3D Modelling Tools 19 Lighting strategies 3ds max v7

3D Modelling Tools 20 Planning lighting Default lighting Use this until you are happy with the scene, then add lights Use as few as possible Start with the key light Maybe a spot Add fill Use omni or several spots Finally add accent lighting 3ds max v7

3D Modelling Tools 21 Ambient light Not a light source Light from other sources bouncing of walls, the ceiling and other objects in the scene 3ds max v7

3D Modelling Tools 22 Types of lighting Standard Spotlights Omnidirectional light Directional light Advanced Photometric lights

3D Modelling Tools 23 Spotlights Casts a focused beam of light like a flashlight, a follow spot in a theatre, or a car headlight 3ds max v7

3D Modelling Tools 24 Omnidirectional light Known as omni light Like a bare light bulb Casts rays in all directions from a single source 3ds max v7

3D Modelling Tools 25 Directional light Also known as Distant lights Cast parallel light rays Primarily used to simulate sunlight

3D Modelling Tools 26 Target lights Concept like cameras Target Easier to aim Simply position the target object at the centre of interest Free 3ds max v7

3D Modelling Tools 27 Lighting direction Single light from side Single light straight on Both sides Reduced full fill 3ds max v7

3D Modelling Tools 28 Activity Create a flat surface with a sphere and a cone sitting on top Add one or more spotlights to provide lighting and render the scene Experiment with moving them around and rendering the effect Add an omni light behind the scene Alter the values to achieve a balanced rendering

3D Modelling Tools 29 Standard light settings Intensity Angle of incidence Attenuation Reflected light and ambient light Colour

3D Modelling Tools 30 Attenuation Natural reduction of light intensity 3ds max v7

3D Modelling Tools 31 Brightness and colour Intensity sets the brightness of the scene Range from 0 to 255 (white) Colour – use the RGB sliders 3ds max v7

3D Modelling Tools 32 Activity With your scene experiment with your light settings Vary the light settings for: Intensity Angle of incidence Attenuation Reflected light and ambient light Colour

3D Modelling Tools 33 Use of shadows Default lighting Spot plus low level back lighting Spot 3ds max v7

3D Modelling Tools 34 Shadows Photometric and standard lights both have the same options for generating shadows Two types Shadow mapped Ray-traced

3D Modelling Tools 35 Shadow mapped Grayscaled texture map based on the lighting and mesh Soft-edged More natural May be blocky May be inaccurate May be incorrectly positioned Do not take transparency into account Do not take on the colour cast of the object May use a lot of RAM 3ds max v7

3D Modelling Tools 36 Ray traced shadows Ray tracing techniques Have a hard edge Software can be used to soften Very accurate and precise Does not use a lot of RAM 3ds max v7

3D Modelling Tools 37 Hotspot and falloff Hotspot Angle of the inner portion of the beam Falloff Angle of the outer beam Differences in angles make the effect softer 3ds max v7

3D Modelling Tools 38 Include and exclude Some software allows you to set up lights that affect only certain objects Use a pick list to select objects

3D Modelling Tools 39 Colour and mood Cool colours – blues and violets Still and calm Warm colours – yellows, red and orange Fiery and energetic Intense and active Be careful, keep it subtle

3D Modelling Tools 40 Activity Create a flat surface with a sphere and a cone sitting on top Add a spot light Add a fill light Alter the hotspot/fallout Alter the type of shadow

3D Modelling Tools 41 Photometric lights Photometric lights enable you to more accurately define lights as they would be in the real world using ray tracing Distribution, intensity, colour temperature can be set 3ds max v7

3D Modelling Tools 42 Global Illumination with Radiosity Standard lights are simpler than natural lighting Using photometric lights with a radiosity solution with your lights provides a better model of the real world Radiosity is rendering technology that realistically simulates the way in which light interacts in an environment

3D Modelling Tools 43 Preset photometric lights Generic 60W Bulb Generic 75W Bulb Generic 100W Bulb Generic Halogen Spotlight Generic Recessed 75W Lamp (web) Generic Recessed 75W Wallwash (web) Generic Recessed 250W Wallwash (web) Generic 4ft Pendant Fluorescent (web) Generic 4ft Cove Fluorescent (web) Generic Street 400W Lamp (web) Generic Stadium 100W Lamp (web)

3D Modelling Tools 44 Photometric lights Target Point Similar to a standard omni light, emits light from a geometric point Spotlight Focused beam Web distribution Distribution of light Many lighting manufacturers provide web files that model their products 3ds max v7

3D Modelling Tools 45 Sunlight and Daylight A system that follows the geographically correct angle and movement of the sun over the earth at a given location You can choose Location Date and time Compass orientation. 3ds max v7

3D Modelling Tools 46 Daylight Daylight combines sunlight and skylight The sunlight component can be either IES Sun light Illuminating Engineering Society Values set automatically based on geographic location, time, and date Or a standard light (a target direct light). The sky component can be either an IES Sky light Or a Skylight.

3D Modelling Tools 47 Portfolio 9 Create a model with a cone, sphere and tube sitting on a flat surface with lighting to show: Strong directional lighting, similar to on a stage A general well lit scene Produce 2 A4 sheets, one for each scene containing a small rendering of the scene and an annotated plan showing and describing the lights used

3D Modelling Tools 48 Questions List and describe three different light types used in 3D modelling giving their parameters and examples of their use Describe, giving light types, parameters and positions how you would light a scene: A stage A well lit indoor room A darkened room light by a candle Consider how this might be done as a storyboard Discuss the difficulties in including shadows within games

3D Modelling Tools 49 Impendent study Directed reading 3DS Max 7 Bible Read Chapters 27 Portfolio 9 Tutorials Introduction to Lighting

3D Modelling Tools 50 References 3ds max v7, (2005) User Reference and Tutorials Murdock K.L., (2005) 3DS Max 7 Bible, John Wiley & Sons Inc, ISBN: Reynolds C., (2003) Stylized Depiction: Non-Photorealistic, Painterly and 'Toon Rendering, accessed 09/01/2007