8/9/2019 29 CapstonePoster 3DScanning Final

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3D Surface Scanning and Reconstruction Via Structured Light Methods

Click: See the World in 3D

Abstract

Background

ResultsMethods

Max Larner, Nabjot Sandhu, Mark Ortiz, Kathleen Chung, Chai Lor,Changqing LiSchool of Engineering, University of California, Merced

Acknowledgements

References

Conclusion

The code used in the programming was originated at BrownUniversity and can be found at the following address:

http://mesh.brown.edu/dlanman/scan3d.

Guidance was provided by Dr. Changquing Li and Chai Lor.

Additional thanks to Matthew Carfano for the company logo.

1.http://mesh.brown.edu/3DPGP-2009/index.html2. http://code.google.com/p/structured-

light/downloads/detail?name=ThreePhase-1-win.zip&can=2&q=

3. Zhang S, Huang PS; Novel method for structured light system

calibration. Opt. Eng. 0001;45(8):083601-083601-8.

Coding:

An open source C++ code from Brown Universitywas used[1]. Modifications to the code were made

to make it specific and compatible for the specific

equipment used to carry out the experiment.

Visual Studio was used to run and modify the

code, then Meshlab, which is also an open source

program was used for the surface reconstruction

from the point clouds.

1. Implement code for camera and projector

calibrations[1, derived from 3].

2. Implement structured light scanner.

3. Save images and call them into Meshlab.

4. Use Meshlab to reconstruct surfaces from point

clouds and reconstruct the scanned image.

Physical Setup:

The setup is done on an optical board and

encased by a dark box made out of painted acrylic.

The setup allows for the camera to have a

horizontal view of the specimen. The camera and

pico projector(AAXA P4X) is mounted a certain

distance away from the platform on which the

specimen is placed.

Figure 2. Setup on the optical board

Scanning and reconstruction of an image are key

for the creation of a 3D model. 3D models can becreated through the use of structured light

methods. This was done by using a structured light

method coded in C++. The camera-projector pair

must be calibrated and the object is then scanned

with grey codes. It was concluded that an accurate

3D model can be created with high precision if a

proper calibration technique is used.

3D images can be used in research to accurately

create models of specimens. Current widely used

camera systems capture images in 2D, but to get

accurate measurements and models of the

specimens they need to be viewed as 3D images.

A solution to this problem is the use of structured

light to take scans that can be interpreted as 3D

images. These scans use a series horizontal and

vertical grey patterns. Scans of an object can be

taken using programming languages such as C++.The code for the calibrations and scanning was

found as an open source f ile from Brown

University[1]. The code used various C++ libraries

including OpenCV. The complication with the file

was that it was not compatible with current

operating systems, so modifications were

necessary to run the code. These scans produce

horizontal and vertical interpretations of the

specimen or object being scanned. The individual

interpretations are then decoded to create a depth

map. The depth map is then used to construct a

point cloud which can then be saved as .wrl files.

The models can be opened with a program such

as Meshlab which is used to process and edit 3Dpoint clouds. In Meshlab these individual points

are reconstructed into a surface which can be

meshed into a well defined 3D image.

Location

Actual

(mm)

Imaged

(mm) %Error

Top to First Ring 68 68.32 0.470588Top to Second Ring 74 73.54 -0.62162

Across Top 58 55.57 -4.18966

Inner Rectangle 31 30.45 -1.77419

Between Rings 7 7.15 2.142857

Figure 4. Untouched scan image

Figure 5. Cleaned scan image, all

extraneous points removed

Figure 6. Reconstructed surface

image with residual normals

Figure 7. Complete meshed

and surfaced object surface

Figure 1.Calibration board

used for camera and

projector pair

Results from the scans indicate that calibration

plays a large role in obtaining an accurate scan.When calibration is properly preformed, resolution

within 5% (