Three-Dimensional Programming (P3D)
The Goal! This course introduces the concepts and theory of a modern photorealistic rendering. Through the ideas and software in this course (Physics laws-based light transport model versus empiric light model) the students will learn to design and develop a rendering system for creating stunning imagery.
What You’ll Learn! • You’ve learned how to develop interactive applications by using OpenGL API • Local (or direct) illumination: only source lights contribution • Global (or indirect) illumination: constant ambient and different “tricks” to simulate photorealistic effects like shadows, reflections or environmental mapping (AVT: done in GPU by using GLSL programming) • Now we are interested in true Global Illumination: • Enhanced Ray Tracer algorithm with Spatial partition, Soft Shadows and Monte Carlo techniques (anti-aliasing and depth-of-field) • UNITY 3D-based application development by using its Assets library and the built-in shaders for photorealistic appearance • Or, in alternative, • Develop a Monte Carlo-based integrator for the rendering equation, like Path-Tracing • Use another Physically-based renderer
You’ll be able to do THIS!
Teachers! Prof. João Madeiras Pereira (INESC-ID) jap@inesc-id.pt
Prerequisites Previous experience on Computer Graphics Good knowledge of C/C++ programming Data structures (lists, arrays, trees…) Geometry Linear Algebra Object programming skills
Warning P3D Course is programming intensive Best way to learn applied topics such this is done by coding If you feel uncomfortable with coding, be aware Consider yourselves warned No excuses accepted afterwards
Bibliography Kevin Suffern, “Ray Tracing from the Ground Up”, AK. Peters, 2007 ; http://www.raytracegroundup.com
Bibliography Matt Pharr, Wenzel Jakob, Greg Humphreys, “Physically Based Rendering : From Theory to Implementation”, Third Edition , Morgan Kaufmann, 2017 http://www.pbrt.org
Bibliography Tomas Möller , Eric Haines, “Real - Time Rendering”, Fourth Edition, AK. Peters, 2018 www.realtimerendering.com/
Tentative Schedule Presentation 1 18-Fev 3D Rendering: Visibility and Visual Apperance Rasterization and Ray-Tracing Enrollment 2 25-Fev Férias Carnaval Férias Carnaval Férias Carnaval Overview de Ray Tracing ; Whitted ray-tracer RT 1 – Diffuse and Shadows Exercise 1 3 3-Mar introduction Whitted Ray-Tracer Implementation 4 10-Mar Geometric Intersections: plane and sphere RT 1 – Diffuse and Shadows (cont.) Exercise 1 (cont.) Checkpoint 1 5 17-Mar Geometric Intersections RT 2 – Reflections and Refractions Distribution Ray-Tracing: Sampling Techniques 6 24-Mar Anti-aliasing, Soft Shadows RT 3 Exercise 2 Distribution Ray-Tracing (cont.) : Depth of 7 31-Mar Field, Motion Blur; Introduction to Grid Acceleration RT 4 Exercise 3 8 7-Abr Férias Pascoa Férias Pascoa Férias Pascoa Mini-teste 1 9 14-Abr Grid Acceleration RT 5 - Soft Shadow e Anti-aliasing, DOF Exercise 3 (cont.) 10 21-Abr Checkpoint 2 Other Acceleration Data structures RT 6 - Grid Acceleration Global Illumination: Theoretical Foundations 11 28-Abr Rendering Equation UNITY 3D/ Other Exercise 4 Mini-teste 2 12 5-Mai UNITY 3D/ Other Exercise 5 Método Monte Carlo ; Materials (BSDF) and 13 12-Mai Lights; Path Tracing UNITY 3D/ Other Exercise 6 14 19-Mai Mini-Teste Repescagem UNITY 3D/ Other Checkpoint 3 15 26-Mai BDPT and Vertex Connection Merging
Grading Policy Theory (20%) – no minimum grade 2 written mini-tests ( 10% each): MT 1: 14 th April MT 2: 5 th May Repetition: 19 th May Labs (80%) – minimum grade: 9.5 Checkpoint 1 (15%): 17 th March; Checkpoint 2 (30%): 21 st April; Checkpoint 3 (35%): 26 th May
3D Rendering A beginners level introduction: https://www.scratchapixel.com/lessons/3d- basic-rendering/rendering-3d-scene- overview
3D Rendering Rendering[ren-der-ing]: The process of generating an image from a model, by means of a computer program.
3D Rendering Rendering[ren-der-ing]: The process of generating an image from a model, by means of a computer program.
3D Rendering Rendering[ren-der-ing]: The process of generating an image from a model, by means of a computer program. Visibility
3D Rendering Rendering[ren-der-ing]: The process of generating an image from a model, by means of a computer program.
3D Rendering Rendering[ren-der-ing]: The process of generating an image from a model, by means of a computer program.
3D Rendering Light Pixel (RGB) Camera Illumination y e z e Objects eye x e y w x w z w
3D Rendering Rendering process could be looked at a two steps process: • Visibility: projecting 3D shapes on the surface of a canvas and determining which part of these surfaces are visible from a given point of view, • Light Simulation: simulating the way light propagates through space, which combined with a description of the way light interacts with the materials objects are made of, will give these objects their final appearance (their color, their brightness, their texture, etc.).
Light Simulation It determines the Visual Appearance • The appearance of objects, only depends on 1) how the way light interacts with matter and 2) how it travels trough space. • All these effects can be broadly divided in two categories: • Shading : techniques related to the way an object interacts with light . • Light Transport : techniques related to how much light an object receives. • Direct illumination • Indirect (global) illumination
Photorealism • Shadows • Reflections (Mirrors) • Transparency • Translucency • Inter-reflections • Detail (Textures…) • Realistic Materials • And many more
Rendering strategies • Rasterization-based • Ray Tracing-based
Ray tracing-based rendering • Uses physics to simulate the interaction between matter and light (shading) as well as the light transport around the scene. • When measurable/predictive photorealism is the primary goal….
Visual Consistency
Physically-based Rendering demo Physics laws-based light transport model
Real-Time Ray-Tracing (RTRT)
Real-Time Ray-Tracing (RTRT)
RTRT in Games
In summary Rendering: Create a 2D picture of a 3D world Two-step process: Visibility and Light Simulation Visibility • To create a photorealistic image, we need to determine which part of the scene is visible from a given viewpoint. • Two methods: Rasterization and Ray-Tracing Light Simulation • The appearance of objects, only depends on the way light interacts with matter and travels trough space. • All these effects can be broadly divided in two categories: • Some effects relate to the way object appear ( Shading ) . • Some effects relate to how much light an object receives ( Light Transport ).
Visibility in Rasterization Conceptual Graphics pipeline with two stages: geometric transformations and rasterization Explicit projection operation (implicit projection lines) : perspective or orthographic matrix transformations
Visibility in Ray-Tracing • Start from the pixel: convert it into a point on the image plane (P’) and then trace a ray from the eye towards the scene passing through P’ • Explicit tracing rays from the eye: implicit projection operation P’
Opaque materials From https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-shading
Mirror objects • Simulate mirror-like material • Physics reflection law - the outgoing or reflected direction of this ray is a reflection of the incoming or incident direction about the normal at the point of incidence
Diifuse color • Color of the material is defined by the diffuse reflection • Diffuse materials modeled by the Lambert law • Incident light is equally spread in every directions above the point of incidence: the outgoing direction has no correlation whatsoever with the incident direction
Specular color • Glossy or shiny materials: not perfectly reflective (like a mirror) nor perfectly diffuse • Referred as specular reflection and is related with the roughness of the surface • Empirical Blinn-Phong reflection model
Phong Reflection Model ˆ r ˆ ˆ v n ˆ L p i Specular Ambient Diffuse ˆ ˆ ˆ ˆ n C C C k C k n L r v amb luz dif luz s
Diffuse vs Specular
Transparent Objects Transparency Snell law – direction of refracted ray Fresnel´s equation: how much light is being reflected vs refracted
Ray-Tracing Ray tracing combines... ...hidden surface removal ...shading due to direct illumination ...shading due to global (indirect) illumination from the environment ...shadow computation
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