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CoDA Training - Basics of 3D Graphics

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This is a keynote I used in a workshop about Cultural 3D held in 2011 at the Center for Digital Archaeology @ UC Berkeley (www.codifi.info)

This is a keynote I used in a workshop about Cultural 3D held in 2011 at the Center for Digital Archaeology @ UC Berkeley (www.codifi.info)


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  • 1. 10 mar 20113D Modeling for Cultural Heritage with Blender (2) Basic Concepts of 3D GraphicsCoDA Center for Digital Archaeology -UC Berkeley www.codifi.info E.Toffalori elena@codifi.info
  • 2. 3D Modeling for Cultural Heritage with Blender Basic concepts of 3D Graphics: SUMMARY Working view Rendering 3D data embedded in Materials and Textures 2D formats Lights and Cameras 3D data types Other entities Encoding of data Software Overview
  • 3. - Basic concepts of 3D Graphics - 3D data embedded in 2D formats Tra ditional Cartography and engineering drawings (and their digital form, CAD or GIS)http://commons.wikimedia.org
  • 4. - Basic concepts of 3D Graphics - 3D data embedded in 2D formats Tra ditional Cartography and engineering drawings Normal map (a raster image that assigns a direction value to every pixel of a surface, encoded in RGB values)http://www.blender.org
  • 5. - Basic concepts of 3D Graphics - 3D data embedded in 2D formats Tra ditional Cartography and engineering drawings Normal map Reflectance Transformation Imaging (Dynamic relighting)http://www.c-h-i.org
  • 6. - Basic concepts of 3D Graphics - 3D data embedded in 2D formatsTra ditional Cartographyand engineering drawingsNormal mapReflectance TransformationImagingStereographic images andvideo (offset images presentedseparately to R/L eye)
  • 7. - Basic concepts of 3D Graphics -3D data embedded in 2D formats http://commons.wikimedia.org
  • 8. - Basic concepts of 3D Graphics - 3D data embedded in 2D formatsTraditional Cartography andengineering drawingsNormal mapReflectance TransformationImagingStereographic images andvideoSculpted prims (a particulartype of normal map, standard formatof detailed meshes in Second Life)
  • 9. - Basic concepts of 3D Graphics - 3D data typesPOINT CLOUD Points identified by XYZ values; Main metho d for automatic acquisition of massive 3D data; Output fo r m at for p hoto g ra m m et r y and photomodeling; Controllable resolution; Light data structure - allows storage of huge quantities of data
  • 10. - Basic concepts of 3D Graphics - 3D data types POINT CLOUDFrom laser-scanning we can alternativelyobtain boundary representations (TIN =Triangulated Irregular Networks)Issue with laser scanning, apart fromdim ensio ns, is the n ee d of hu maninterpretation! (Time consuming, more likelyto become unusable)http://archive.cyark.org/
  • 11. - Basic concepts of 3D Graphics - 3D data typesPOINT CLOUD 3D version of pixel, regular grid of cubes;VOXEL controllable, finite resolution; volume/weight computing or division into sub-volumes; visualization of scientific data (often sampled in a regular grid); 3D printing;
  • 12. - Basic concepts of 3D Graphics - 3D data types POINT CLOUD VOXELhttp://nasaimages.org
  • 13. - Basic concepts of 3D Graphics - 3D data typesPOINT CLOUD vector-based drawing system; based on lines and polylines,VOXEL secondarily on surfaces and volumes;C A D = C o m p ute rAided Design in archaeolo gy, u se d fo r manually acquired 3D data from total-station; mainly used for architectural s ca le (g e n e ra l p la n s, digitization of field drawings);
  • 14. - Basic concepts of 3D Graphics - 3D data types E.Toffalori
  • 15. - Basic concepts of 3D Graphics - 3D data typesPOINT CLOUD collection of vertices, edges and faces that can be freely moved;VOXEL most co m mo n fo r mat fo rCAD ‘freehand’ or manual modeling;Polygonal MESH ba s e d o n pr i m it i v e s a n d modified by means of subdivision and addition of vertices and detail; main format for Blender, too!!!
  • 16. - Basic concepts of 3D Graphics - 3D data types POINT CLOUD VOXEL CAD Polygonal MESHhttp://www.blender.org
  • 17. - Basic concepts of 3D Graphics - 3D data typesPOINT CLOUD parametric curves or surfaces; handled more efficiently thanVOXEL meshes, but they allow more limited changes;CAD a NURBS sphere will alwaysPolygonal MESH be rendered as a perfect circle (whereas I will see edges on a mesh)...NURBS ...but I can’t texture it in detail...
  • 18. - Basic concepts of 3D Graphics - 3D data types POINT CLOUD VOXEL CAD Polygonal MESH NURBShttp://en.wikipedia.org
  • 19. - Basic concepts of 3D Graphics - 3D data typesPOINT CLOUD generate d through enco de d r u le s (S h a p e G e n e rato r Language);VOXEL can provide infinite variations ofCAD models within certain rules (representation of randomness, self-similarity, repetitiveness);Polygonal MESH i nte g rate d w it h ot h e rNURBS techniques;Procedural Modeling often aimed to high-quality rendering of urban landscapes;
  • 20. - Basic concepts of 3D Graphics - 3D data types POINT CLOUD VOXEL CAD Polygonal MESH NURBS Procedural Modelinghttp://www.procedural.com
  • 21. - Basic concepts of 3D Graphics - Encoding of data: examplescode of a NURBS sphere code of a MESH sphere (.wrl) (.dae)
  • 22. - Basic concepts of 3D Graphics - Encoding of data: examples City Engine: generative code of...
  • 23. - Basic concepts of 3D Graphics - Encoding of data: examples .... a whole city!
  • 24. - Basic concepts of 3D Graphics - Encoding of dataThe core level of 3D data is the geometricalstructure; this can be encoded either in an ASCII/human-readable format (like Google .KMZ and otherCollada files) or in a binary format (.blend files);Editing to the geometric structure can be donedirectly inside the code (ASCII formats)......or through an interface provided by the 3Dmodeling software; (not always graphic: see AutoCADtext shell, Blender Python Scripting Console...)
  • 25. - Basic concepts of 3D Graphics - Working view: examples Blender
  • 26. - Basic concepts of 3D Graphics - Working view: examples 3DS Max
  • 27. - Basic concepts of 3D Graphics - Working view: examples Maya
  • 28. - Basic concepts of 3D Graphics - Working view: examples Google SketchUp
  • 29. - Basic concepts of 3D Graphics - RenderingA RENDERING is not a working space anymore;While it can still be interactive (video games,virtual environments, 3D PDF), it doesn’t allowchanges to the model;given a certain dataset, a rendering is the resultof the computing process, returning a value forevery pixel of our monitor or display device;It can refer to a still image, a video animation oran interactive scene;
  • 30. - Basic concepts of 3D Graphics - RenderingRENDERING ENGINES some 3D modelers have an internalrenderer, but besides this they rely on third party modulesfor rendering Final Render Brazil V-Ray Mental-Ray Render-Man (Pixar) YafaRay...
  • 31. - Basic concepts of 3D Graphics - RenderingThe same scene rendered with different engines will returndifferent results in terms of material, light and color treatment; http://yorik.uncreated.net/tutorials/blender-renderers.html
  • 32. - Basic concepts of 3D Graphics - Materials and TexturesThe way we make 3D modelslook realistic, conversely to graycubes and shapes, is by meansof materials and textures;
  • 33. - Basic concepts of 3D Graphics - Materials and TexturesThe way we make 3D modelslook realistic, conversely to graycubes and shapes, is by meansof materials and textures;Materials control color andshading of objects, and detailthe way they will react tolight;You can find samples of complexmaterials, such as human skin,on the web in 3D graphics blogsand repositories (see below forBlender resources);
  • 34. - Basic concepts of 3D Graphics - Materials and Textures Material and texture settings in Blender
  • 35. - Basic concepts of 3D Graphics - Materials and Textures A material can feature one or more textures, that is, raster images projected onto the faces of a 3D model; 2D textures need to be mapped on the 3D space of the object, this can be done through the mo deler’s built-in projection fu nctio ns (such as “cube”, “cylinder”, “sphere”...) ... or through UVW mapping in a more detailed wayhttp://www.blender.org
  • 36. - Basic concepts of 3D Graphics - Materials and Textures UVW MAPPING: UVW is an alternative acronym to XYZ for a tridimensional cartesian space, used for describing the mapping process between the texture space and the model space;http://www.blender.org
  • 37. - Basic concepts of 3D Graphics - Materials and Textures UVW MAPPING: UVW is an alternative acronym to XYZ for a tridimensional cartesian space, used for describing the mapping process between the texture space and the model space; Once a mesh is unfolded into a 2D texture space, every vertex will be assigne d a UV (2D)position besides its XYZ (3D)position;http://www.blender.org
  • 38. - Basic concepts of 3D Graphics - Materials and TexturesPHOTOGRAPHIC VS PROCEDURAL TEXTURE;Textures can be external raster images, such asphotographs or drawings... (When modeling something existing in the realworld, you may want to use photographs of the real object or building, whilst when modelinga project, a virtual world or archaeological features, plausible photographs form other contextsor drawings will work well);Or they can be generated algorithmically inside themodeling software (Procedural textures guarantee non-repetitive, uniform coverage,but they hardly represent realistically real materials. However, they can be overlaid onphotographic textures to create irregular pattern, such as dirt or rust);
  • 39. - Basic concepts of 3D Graphics - Realistic Texturing
  • 40. - Basic concepts of 3D Graphics - Realistic Texturing
  • 41. - Basic concepts of 3D Graphics - Materials and TexturesTEXTURES TO MODIFY OTHER VALUES;Textures aren’t used to just modify color, but alsoother values’ intensity (grayscale); BUMP and NORMALS DISPLACEMENT ALPHA SPECULARITY-REFLECTIVITY-MIRROR ...
  • 42. - Basic concepts of 3D Graphics - Materials and TexturesB U M P (g ra y s ca le) a n dN O R M A L ( RG B) tex t u re ssimulate a detailed 3D surfaceon a flat face; they are usedto increase detail of themodel without increasing itsgeometric complexity;
  • 43. - Basic concepts of 3D Graphics - Materials and TexturesB U M P (g ra y s ca le) i m a g e sexpress the relative “height” (Wcoordinate in the UVW texture-space) of every pixelThey don’t actually mo difygeometry: such irregularitieswon’t cast a shadow or occludeother objects, they just modifythe way light interacts withthe surface.A bump texture is often theb&w version of the full-colortexture:;
  • 44. - Basic concepts of 3D Graphics - Materials and Textures NORMAL textures encode into an RGB value the direction of the normal (perpendicular) to the surface in every point; They can be baked from a h i g h - d eta i l m e s h a n d pr oj e cte d o n a lo w e r - resolution model to simulate detailed surface; * Sculpted Prims used in Second Life are a particular kind of normal texture, storing surface position instead of normal direction (XYZ space is mapped to RGB values);http://www.blender.org
  • 45. - Basic concepts of 3D Graphics - Materials and TexturesD I S P L A C E M E N T te x t u r e sactually modify the geometrycreating bumps, creases andridges, thus they need surfacesto be subdivided accordingly tothe desired level of detail;ALPHA affects transparency ofobject areas;SPECULARITY, REFLECTIVITY,M I R RO R c h a n g e t h e w a ydifferent areas react to light;http://www.blender.org
  • 46. - Basic concepts of 3D Graphics - Lights and CamerasIn modeling software based on a3D scene setup, cameras and lightsare treated as virtual objects too;Position, dimension, scale, direction,angle, light intensity and “lens”settings;Lighting for a realistic result mustsimulate real world conditions(t r ic k s a n d pr i n c ip le s f r o mphotography lighting);Similarly, animation requires somedirectio n skills to mo ve theinternal camera around;
  • 47. - Basic concepts of 3D Graphics - Lights and CamerasRAY TRACING calculates castingrays from the light source and thereflected amount per pixel in therendering; ver slow but precise, itallo ws so ph isticate d effe cts,transparency, mirroring...;R. is also u se d to calculaterendering, that is, what is visibleor occluded from camera position;BUFFER is a “cheaper” effect,based on the Z-position of faceswith respect to the source of light,faster to render, thus used mostlyin real-time and video rendering;
  • 48. - Basic concepts of 3D Graphics - Lights and Cameras“Raytracing can be used to make a material reflect its surroundings, like amirror. The principle of raytraced reflections is very simple: a ray is fired fromthe camera and travels through the scene until it encounters an object. If thefirst object hit by the ray is not reflective, then the ray takes the color of theobject. If the object is reflective, then the ray bounces from its currentlocation and travels up to another object, and so on, until a non-reflectiveobject is finally met and gives the whole chain of rays its color. ”http://wiki.blender.org/
  • 49. - Basic concepts of 3D Graphics - Other entities Hierarchic structures; Armatures; Instances, Groups, Parents; Fluids and particular systems; Constraint and interactions between objects; Game interactions (events responding to the user input);http://www.blendswap.com/
  • 50. - Basic concepts of 3D Graphics - Software Overview: GeneralAutodesk AutoCAD Maxon Cinema 4D(architecture, design and (imaging and animation)engineering) Google SketchUp (web-Autodesk 3DS Max contents; architecture and(architecture, animation and interiors)characters) Blender (animation,Autodesk Maya characters, video games)(imaging, animation andcharacters)
  • 51. - Basic concepts of 3D Graphics - Software Overview: Specialized Rhino 3D (organic modeling) V i s u a l Nat u re ( la n d s ca p e s, ecosystems) MeshLab (unstructured point-clouds and meshes; architecture and objects) Procedural CityEngine (imaging; architecture and urban landscapes) Chemical and medical industry...http://commons.wikimedia.org
  • 52. - Basic concepts of 3D Graphics - Software Overview: Game engines/scene managers Blender OGRE Open Scene Graph Unity 3D Virtools ...http://unity3d.com/gallery/
  • 53. - Basic concepts of 3D Graphics - Software Overview: Viewers and web pluginA c r o b at R e a d e r ( P D F -embedded U3D);Google Earth + pluginUnity 3DAdobe FlashHTML5Java / Python-based plugin