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# A Flexible Camera Calibration Tool for 3D Capture PowerPoint PPT Presentation

A Flexible Camera Calibration Tool for 3D Capture. Lei Wang Media and Machine Lab Advisor: Cindy Grimm. 3D Capture. Data Acquisition Camera Calibration Shape Integration Texture Synthesis Shape Texture Integration. Camera Calibration. Camera Model Global Approach Requirement

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A Flexible Camera Calibration Tool for 3D Capture

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## A Flexible Camera Calibration Tool for 3D Capture

Lei Wang

Media and Machine Lab

### 3D Capture

• Data Acquisition

• Camera Calibration

• Shape Integration

• Texture Synthesis

• Shape Texture Integration

### Camera Calibration

• Camera Model

• Global Approach

• Requirement

• Previous Work

• Our Approach

• Conclusion

### Denotation

• 2D Point: m = [u, v, 1]T

• 3D Point: M = [X, Y, Z]T

• 2D – 3D: s m =A [R T] M

• A: Intrinsic Parameters

• [R T]: Extrinsic Parameters

### Global Approach

• Take pictures

• Detect the pattern

• Extract the feature

• Solve for intrinsic parameters (one for all)

• Solve for extrinsic parameters (one for each)

### Requirement

• Automated

• Hemisphere Visibility

• Not occlude the object

• Robust on lighting conditions

• Easy to build

• Easy to detect

### Planar Pattern

• Checkerboard

Tsai’s Algorithm

Zhang’s Algorithm

• Geometry Pattern

• Concentric Circle

Jun-Sik Kim, Ho-Won Kim and In-So Kweon’s Algorithm

### Improved Planar Pattern

• Move the pattern by hand

• Place two or more patterns on different plane

• Place mirrors and use the additional reflected pattern

### Our Approach – Outline

• Design Calibrating Pattern

• Build Calibrating Pattern

• Feature Extraction

• Feature Mapping – Gradient Search

• Test

### Cone with basic 3D shapes

• Automated

• Hemisphere visibility

• Not occlude the object: part of the shape is enough for relying on a group of points

• Robust for lighting conditions: color ratio

• Easy to detect: color boundary

• Easy to build: build from a planar pattern

• Circles

• Ellipses

• Lines

• Points

• Line

• Circle

• Ellipse

### The Printable Planar Pattern

• 3D equation, 2D print translation

• Physical tips

• Color ratio

• Grouping

### Ellipses

• Ellipse detection

• Ellipse fitting

### Lines

• Line detection

• Line fitting

### Points

• Direct Point detection

• Intersection of two shapes

- Line-line intersection

- Line-circle intersection

- Line-ellipse intersection

- Ellipse-ellipse intersection(not recommend)

### Solve for Intrinsic Parameters

• Checkerboard

• OpenCV

• Flagged Checkerboard

### Extrinsic by Points

• Use Points

• Linear

• Limitation

- Hard to label

- Inaccurate

- Six points rules not guaranteed

### Extrinsic by Shapes

• Other Shape

• Non-Linear

- Cost Function

- Initial Guess

- Step Choose

- Stop Condition

### Extrinsic by Lines

• Cost Function

• Initial Guess

• Step Choose

• Stop Condition

### Extrinsic by Conics

• Cost Function

• Initial Guess

• Step Choose

• Stop Condition

### General Extrinsic

• General Case

• Use Combination Pattern

• Easiness

• Efficiency

• Accuracy