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1. Pedro Davalos MonoSLAM 1 MonoSLAM: Real-Time Single Camera SLAM Davison, Reid, Molton, Stasse – IEEE, 2007
Presented By:
Pedro Davalos
February 25, 2008
2. Pedro Davalos MonoSLAM 2 Localization: Where am I?
3. Pedro Davalos MonoSLAM 3 Mapping: Symbolic Representation of the World
4. Pedro Davalos MonoSLAM 4 Problem Position Estimation
Localization/Mapping Dilemma:
How to determine my Location?
Use a Map!
How do I build a Map?
Knowing my Location!
5. Pedro Davalos MonoSLAM 5 Mapping Examples
6. Pedro Davalos MonoSLAM 6 Where Am I?
7. Pedro Davalos MonoSLAM 7 Background: SLAM Simultaneous Localization And Mapping
“SLAM is concerned with the problem of:
-building a map of an unknown environment by a mobile robot while at the same time
-navigating the environment using the map.”
Early SLAM:
A Stochastic Map for Uncertain Spatial Relationships [Smith, Self, Cheeseman 1987]
Directed Sonar Sensing for Mobile Robot Navigation [Leonard 1990] (PhD)
An Information-Theoretic Approach to Data Fusion and Sensor Management [Manyika 1993]
SLAM [Csorba 1997] (PhD)
Mobile Robot Navigation Using Active Vision [Davison 1998] (PhD)
8. Pedro Davalos MonoSLAM 8 Background: SLAM Landmark Extraction
Data Association
State Estimation
State Update & Landmark Update
9. Pedro Davalos MonoSLAM 9 SLAM Demo
10. Pedro Davalos MonoSLAM 10 Approach Implement Solution for Localization
Use SLAM Technique
With a single Camera (320x240) – calibrated, 100° FOV
Real-Time (30Hz)
Repeatable (drift free)
11. Pedro Davalos MonoSLAM 11 MonoSLAM: Probabilistic 3D Map
12. Pedro Davalos MonoSLAM 12 MonoSLAM: Natural Visual Landmarks Find/add new landmarks (Image Processing)
Scan full image to find salient features [Shi, Tomasi, 1994]
Save Landmarks
Save 11x11 template AND position & orientation*
13. Pedro Davalos MonoSLAM 13 MonoSLAM: System Initialization 3D from single frame?
Startup with know prior reference target in the scene
Provides scale and depth
Allows for immediate normal operation mode
14. Pedro Davalos MonoSLAM 14 MonoSLAM: Motion Model and Prediction Agile Camera with unknown dynamics
Assume: constant velocity and constant angular velocity
Impose smoothness in motion (assume unlikely large accelerations)
15. Pedro Davalos MonoSLAM 15 Active Feature Measurement and Map Update Search and find features by cross-correlation
Minimize search by predicting location on image
Uncertainty in prediction of feature location
16. Pedro Davalos MonoSLAM 16 MonoSLAM: Feature Initialization Identify a distinctive feature
Save camera position, ray from camera to feature, and template
As the camera moves, triangulate position if feature is reobserved
17. Pedro Davalos MonoSLAM 17 MonoSLAM: Map Management Decide when to search for new features?
If less than 12 features in the FOV
Add one feature by searching 80x60 region without features, centric
Decide when to delete bad features
If 50% failure of recognizing features that should be visible
Due to occlusion, moved, specularity,
18. Pedro Davalos MonoSLAM 18 MonoSLAM: Feature Orientation Estimation Goal:
Optimize template matching
invariant to scale, rotation, translation
Approach:
Assume template is plane
Based on Cam position
Predict template normal
Update surface n estimate
Warp template with Homography
19. Pedro Davalos MonoSLAM 19 Test Results Augmented Reality
RealTime tracking 3d position allows 3d overlay
20. Pedro Davalos MonoSLAM 20 Results Humanoid Used remote controlled Humanoid robot
Tracked Position in realtime, 30Hz using:
Single Camera
Also used gyro!
21. Pedro Davalos MonoSLAM 21 Limitations Blank Walls
Lost Robot
100 Features
Small area: room
Heuristics: Thresholds
Estimate Uncertainty
22. Pedro Davalos MonoSLAM 22 Discussion?