mesh colors

MESH COLORS

Author: Cem Yuksel, John Keyser & Donald House

Texas A&M University

SIGGRAPH 2010

Speaker: Chung-Yuan Lee

Yuan-Ze University

OUTLINE

Introduction Previous method

Proposed method Mesh color

Filtering Two-dimensional filtering Mip-map filtering Anisotropic filtering

Analysis Summary Reference

INTRODUCTION

Previous method – texture mapping

Intrinsic problems Mapping discontinuities Limitations to model editing after coloring Incorrect filtering …etc

PROPOSED METHOD – MESH COLOR

There are no mapping discontinuities No mapping function is necessary MIP-mapping for level-of-detail filtering is

supported Models can be edited, after coloring, without

resampling The procedure is compatible with the current

real-time graphics pipeline

MESH COLOR STRUCTURE

Mesh color on triangle faces R means different resolution

MESH COLOR STRUCTURE[1,0,0]

[0,1,0] [0,0,1]

MESH COLOR STRUCTURE

Non-uniform Face Resolutions It is straightforward to up-sample or down-

sample along an edge, if two faces sharing a common edge have different resolutions

MESH COLOR STRUCTURE

Editing Mesh Colored Geometry

MESH COLOR STRUCTURE

Non-triangular Meshes Quadrilaterals

Triangle pair Quadrilateral positioning

NURBS Subdivision surfaces

Dividing faces only

FILTERING

For evaluating the color value at any point on the surface or an area, we need a reconstruction filter

Two-dimensional filtering Nearest Linear

MIP-map filtering Anisotropic filtering

TWO-DIMENSIONAL FILTERING

To compute the color value at target point,we need to find out the weights of nearest 3 point to target point

TWO-DIMENSIONAL FILTERING[1,0,0]

[0,1,0] [0,0,1]

If w = 0, we are at the sample point B

weight

TWO-DIMENSIONAL FILTERING

The weights for those color values are w

TWO-DIMENSIONAL FILTERING

The weights are w’ = [1, 1, 1] − w

TWO-DIMENSIONAL FILTERING

Nearest Use the color of the sample with the highest

weight Linear

By blending the colors using the weights

MIP-MAP FILTERING

This face will have n+1 MIP-map levels

MIP-MAP FILTERING

MIP-MAP FILTERING

Face & Edge Vertex

Where Cei is the nearest edge color at the higher level for adjacent edge i

ANISOTROPIC FILTERING

Original

MIP-map filtering

Trilinear filtering

Circularity Distortion

Mapping Chasm

Too fuzzy

ANISOTROPIC FILTERING

original

2x Anisotropic filtering

16xMIP-map filtering

FILTERING

ANALYSIS

Unified content creation

‧Modeling & Painting together

ANALYSIS

Memory efficient

Reduce 20% memory requirement !

Fast

ANALYSIS

hardware

Hardware

Texture mapping on hardware is ~20x faster

ANALYSIS

Correct filtering

SUMMARY

No mapping No Discontinuities Guaranteed 1-1 Correspondence Correct MIP-map Filtering Local Resolution Adjustment Modeling with Painting Compatible with Current Pipeline

SUMMARY Easy to use (for end user) Easy to implement High quality High performance

Mesh Colors will do better than texture mapping , if it has support from Hardware !

REFERENCE

Pictures for Mesh color Cem Yuksel, John Keyser & Donald H. House Texas A&M University “Mesh Colors,“ ACM Transactions on Graphics

(TOG), 29(2) 2010 Pictures for Anisotropic filtering

http://www.csie.ntu.edu.tw/~r89004/hive/mipmap/page_4.html

Copyright© 2000, 2001, 2002 Ping-Che Chen