Texture Mapping Objectives Introduce Mapping Methods Texture Mapping

Texture Mapping Objectives  Introduce Mapping Methods Texture Mapping

Texture Mapping Objectives Introduce Mapping Methods Texture Mapping Environment Mapping Bump Mapping Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 2 The Limits of Geometric

Modeling Although graphics cards can render over 10 million polygons per second, that number is insufficient for many phenomena Clouds Grass Terrain Skin Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 3

Modeling an Orange Consider the problem of modeling an orange (the fruit) Start with an orange-colored sphere Too simple Replace sphere with a more complex shape Does not capture surface characteristics (small dimples) Takes too many polygons to model all the dimples Angel: Interactive Computer Graphics 5E Addison-Wesley 2009

4 Modeling an Orange (2) Take a picture of a real orange, scan it, and paste onto simple geometric model This process is known as texture mapping Still might not be sufficient because resulting surface will be smooth Need to change local shape Bump mapping Angel: Interactive Computer Graphics 5E Addison-Wesley 2009

5 Three Types of Mapping Texture Mapping Uses images to fill inside of polygons Environment (reflection mapping) Uses a picture of the environment for texture maps Allows simulation of highly specular surfaces Bump mapping

Emulates altering normal vectors during the rendering process Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 6 Texture Mapping geometric model texture mapped Angel: Interactive Computer Graphics 5E Addison-Wesley 2009

7 Environment Mapping Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 8 Bump Mapping Angel: Interactive Computer Graphics 5E Addison-Wesley 2009

9 Where does mapping take place? Mapping techniques are implemented at the end of the rendering pipeline Very efficient because few polygons make it past the clipper Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 10

Is it simple? Although the idea is simple---map an image to a surface---there are 3 or 4 coordinate systems involved 2D image 3D surface Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 11 Coordinate Systems Parametric coordinates

May be used to model curves and surfaces Texture coordinates Used to identify points in the image to be mapped Object or World Coordinates Conceptually, where the mapping takes place Window Coordinates Where the final image is really produced Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 12

Texture Mapping parametric coordinates texture coordinates world coordinates Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 window coordinates 13 Mapping Functions Basic problem is how to find the maps

Consider mapping from texture coordinates to a point a surface Appear to need three functions x = x(s,t) y = y(s,t) z = z(s,t) (x,y,z) t But we really want to go the other way

s Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 14 Backward Mapping We really want to go backwards

Given a pixel, we want to know to which point on an object it corresponds Given a point on an object, we want to know to which point in the texture it corresponds Need a map of the form s = s(x,y,z) t = t(x,y,z) Such functions are difficult to find in general Angel: Interactive Computer Graphics 5E Addison-Wesley 2009

15 Two-part mapping One solution to the mapping problem is to first map the texture to a simple intermediate surface Example: map to cylinder Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 16

Cylindrical Mapping parametric cylinder x = r cos 2 u y = r sin 2u z = v/h maps rectangle in u,v space to cylinder of radius r and height h in world coordinates s=u t=v maps from texture space Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 17

Spherical Map We can use a parametric sphere x = r cos 2u y = r sin 2u cos 2v z = r sin 2u sin 2v in a similar manner to the cylinder but have to decide where to put the distortion Spheres are used in environmental maps Angel: Interactive Computer Graphics 5E Addison-Wesley 2009

18 Box Mapping Easy to use with simple orthographic projection Also used in environment maps Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 19 Second Mapping Map from intermediate object to actual object

Normals from intermediate to actual Normals from actual to intermediate Vectors from center of intermediate actual intermediate Angel: Interactive Computer Graphics 5E Addison-Wesley 2009 20

Recently Viewed Presentations

  • Analyze Assure Accelerate Benchmarking Terminology for Protection Performance

    Analyze Assure Accelerate Benchmarking Terminology for Protection Performance

    Several Advantages Not limited to SONET/SDH APS Adopt to MPLS by using a different trigger Measures the effect of failover on IP Other drafts concentrate on control plane only Observes more than packet loss Motivation Different Protection technologies Automatic Protection...
  • Paradigm Shift - Ctebvi

    Paradigm Shift - Ctebvi

    Support for these students include strategies such as scaffolding, or breaking the task into smaller steps. Another support is using a digital tablet where words can be highlighted and defined, or given a synonym. Masking a page so that only...
  • Polygamy Polygamy is illegal in the United States

    Polygamy Polygamy is illegal in the United States

    Polygamy is not limited to the human species. It is widespread among animal populations. Moreover, both forms of polygamy --polygyny and polyandry-- are practiced by other animals. Why do these different mating systems occur in other species? Are the reasons...
  • Drag&Drop Macro: Easter Eggs

    Drag&Drop Macro: Easter Eggs

    Title: Drag&Drop Macro: Easter Eggs Author: Jo Rhys-Jones / Joe Dale Keywords: Search Easter Eggs with Drag&Drop-Makro Description: Macro created by [email protected] Hans Werner Hofmann / Ute Simon
  • The cool bibliography

    The cool bibliography

    The Raven Master's Secret The 12-year-old son of the Raven Master and the tower of London befriends a Jacobite rebel being held prisioner there. AND—There are many more! Watch for the following awesome historical fiction authors: Ann Rinaldi Karen Cushman...
  • Hantavirus Loraine Wu Howard Zeng Yuka Yamaguchi What

    Hantavirus Loraine Wu Howard Zeng Yuka Yamaguchi What

    G1 and G2 proteins are translated on membrane-bound ribosomes. Replication An uncharacterized signal switches transcription to replication. Maybe cytoplasmic accumulation of nucleocapsid proteins. Prime and Realign Model Question 1: How does hantavirus cap the 5' end of its mRNA transcripts?...
  • Molecular evolution: how do we explain the patterns

    Molecular evolution: how do we explain the patterns

    Neutralist vs. selectionist view Are most substitutions due to drift or natural selection? ... aaat aaat aaat aaat acat aaat aaat Time 20: aaat aaat acat aaat acat acat acat Time 30: acat acat acat acat acat acat acat Time...
  • Informationsintegration SchemaSQL 29.11.2005 Felix Naumann berblick Wiederholung Strukturelle

    Informationsintegration SchemaSQL 29.11.2005 Felix Naumann berblick Wiederholung Strukturelle

    Informationsintegration SchemaSQL 29.11.2005 Felix Naumann Überblick Wiederholung Strukturelle Heterogenität Multidatenbanken SchemaSQL Basis-Syntax Aggregation Umstrukturierung Architektur und Implementierung Strukturelle Heterogenität Datenmodell-Heterogenität Relationales Modell XML Modell OO Modell Hierarchisches Modell Schematische Heterogenität Integritätsbedingungen, Schlüssel ...