View
213
Download
0
Tags:
Embed Size (px)
Citation preview
RANSAC-Assisted Display Model Reconstruction for Projective
DisplayPatrick Quirk, Tyler Johnson, Rick Skarbez, Herman Towles, Florian Gyarfas, Henry Fuchs
Department of Computer Science
University of North Carolina at Chapel Hill
Emerging Display Technologies 2006 – March 26, 2006
2 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Multi-Projector Display
3 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Perspectively CorrectP
4 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Perspectively-correct Rendering
P matricesIntrinsics and extrinsics of each projector
Viewer’s locationDisplay Surface Model
New Method for Display Surface Estimation!
5 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Rendering Methods
Rendering Algorithm
1-pass (homography)
2-pass (projective tex.)
Display Shape
Planar surface Complex shaped surface
References
Raskar99,Yang01,Sukthankar01,Chen02, Steele02,Wallace04
Raskar98,Yang-Welch01,Brown02,Cotting04
6 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Display Surface
A Primer: 2-Pass Rendering
1st PassGeometry: application definedViewpoint: user’s positionResult: “ideal image”
2nd PassGeometry: screen surface•Use “ideal image” as projected
texture
Viewpoint: projector’s positionResult: projector’s image
Viewer
Projector
7 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Display Surface Estimation
3D Stereo
Reconstruction
Display Surface Model
Generation3D Point Cloud
Tessellated Mesh
8 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Artifacts with Tessellated Meshes
Inaccurate corner representations
Sampling issue
Texture mapping distortion on planar surfaces
Reconstruction errors
Holes in surface model
Meshing errors
9 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Visual ArtifactsP
10 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Rooms Are Piecewise Planar
New display model estimation method
Fit planes to point cloudConvert planes to polygons for rendering
AdvantageCorners can be accurately estimated (intersection of planes)Noiseless models eliminate texture distortion
11 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
RANSAC Plane Fitting
Random Sample ConsensusDesigned to work with many outliersFinds largest set of inliersCode from Peter Kovesi, Univ. Western Australia
Hypothesis plane from 3 random pointsFinds plane with most inliers
User specified fit tolerance
Fits least-squares plane to these inliers
12 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Method
FitPlane( C )• Fit one plane P to point cloud C using
RANSAC• Remove P inlier points from cloud C’ = C –
Pinliers
• Recursively loop using outliers from this pass as input for next plane
13 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
RANSAC Plane Fitting
14 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Plane To Polygons
Task: What planes intersect?
Reduce complexity to a 2D problemEstablish a “floor” plane orthogonal to the “wall” planesProject wall points onto this planeCasts problem as a line intersection problem
15 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Cast into a 2D Task
Intersecting Line (Plane)
Pairs
Red – Orange
Orange – Green
Green – Cyan
Cyan – Magenta
Magenta – Black
Black – Blue
16 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Results
Less than 2-3% dimensional errorRe-projection: Std. Dev. < 0.5 pixels
17 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Results
Improved corner matching (< 2 pixels)Lack of texture distortion in application scenery
PV
18 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
FlightGear DemoP P
19 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Installations
UNC Lab3 walls with columns in each corner
UNC lobby and I/ITSEC 2005
2-wall corner
Naval Research Lab
3 walls with a column in one corner
20 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
SUMMARY: New Surface Model Generation MethodRecursively extract planes from 3D point cloud with RANSAC-assisted algorithm
Removes outliers easilyFits noisy data well
Convert Planes to Polygons for 2-pass renderingResults in simple, accurate model
Much less distortion than with tessellated mesh
21 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Future Work
Use optimal triangulation algorithmRather than DLT; less noise in data
Generalized Planes to Polygon solutionExtract other surface functions
Applicability of cylinders, quadrics, etc.
Apply techniques to create larger virtual environmentsContinuous calibration/refinement during operation
22 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Thank You
FundingFundingOffice of Naval Research Award N00014-03-1-0589Office of Naval Research Award N00014-03-1-0589• DARWARS Training Superiority program DARWARS Training Superiority program • VIRTE – Virtual Technologies and Environments programVIRTE – Virtual Technologies and Environments program
23 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
24 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Planes to Polygons
1. Compute intersection line between two planes
Align this with Y axis
2. Project down all points to get floorplanLine segments, based on range of inliers
3. Find closest 2D line intersectionsDetermines which planes to intersect
4. Intersect the planes, make height uniform5. Truncate non-intersecting planes (edges)
25 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Room Coordinate System
Motivation Can easily estimate position of viewer
Auto-alignment performedIncorporated into Planes to Polygons algorithm
Chosen to be intersection of planesAlso have tool to change coordinate system
Extends to a tracked user
26 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
3D Stereo Reconstruction
1. Display feature set with projector(s)Checkerboard, Gray-coded stripes, Gaussian blobs, etc.
2. Image with stereo camera pair3. Extract, identify, match feature
points4. Triangulate corresponding points
Model represented by 3D point cloud!
27 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Plane 1
28 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Plane 2
29 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Plane 3
30 RANSAC-Assisted Display (Surface) Model Reconstruction for Projective Display
Plane 4