pro3D: A 3D Scanning System.

Home Page • Sep 1998 •

Pro3D: A 3D Scanning System

Suchit Tiwari
University of Pune
Bachelor of Engineering Computer Science & Engineering
1998-99

Thesis work submitted in partial fulfillment of
Engineering Bachelor degree in Computer Science & Engineering

Author's Contact:
Email: srt@suchit-tiwari.org

©Suchit This is a brief excerpt from a detailed PDF/DOC report. Complete report is available for download upon request. Just drop me a line.

ABSTRACT

Modern computer applications demand high degree of sophistication. Applications like Soft Object Animation, Virtual Reality Applications, Internet Softwares, Commercial Applications, and Scientific Visualizations require realistic representation of day-to-day-life entities. In many of such applications there is a frequent need to represent real-life objects and that to in 3D. There are two different aspects of such representations – one deals with ‘physical representation’ and the other one deals with ‘anatomical representation’. We are interested in ‘physical representation’. Very modern and very futuristic applications like 3D Faxing and Fast Prototyping also require databases of 3D objects. These needs put a problem statement in front of us – to design a profiling system. With the aim of designing a system to acquire 3D surface profile of objects, I started out experimenting with various options. The CTQs (critical to quality) defined were:

Operable without probing

Economical

Accurate

Faster in operation and

Simple in design.

Keywords:3D Scanning, Profiling, Rendering, Mesh Generation, Visualization, 3D Fax, Data Acquisition

1. Introduction

</skipped (review of alternate techniques>

The system architecture consists of a hardware setup and software tools to support production of 3D profiling. refer to figure 1. It shows the hardware schematic of the system.


Figure 1. Hardware Setup for Pro3D.

I used an old overhead projector we had in garage for generating slit light. Slit light caused a slice highlighted from an object. Placing an object on the turn table and rotating it 360 degrees allowed system to capture multiple profiles from all angles. I would generally make a human sit on the rotating chair and then capture the profile. Figure 2 shows that.


Figure 2. Human sits on chair for digitization.

2. Video & Image Processing

I final interesting shooting of myself shows me in 3D.


Figure 3. Myself shooting in slit light source.

Once video was recorded, it was processed using a set of tools I developed for extracting the profile information. The thinning algorithm applied to one of the video frames would extract a source slice like follows:


Figure 4. Image processing using thinning algorithm.

One interesting problem here was that video frame extracted would contain the noise (we had old non-digital camera). And it would break the profile slice. The solution was to detect such "holes" and try to bridge them with respect to the slice profile.


Figure 5. Bridging the holes.

3. Mesh Generation

Once profiles were extracted from entire video, a set of mathematical algorithms would execute to build a wireframe out of that data. Various approaches could be tried out before deciding the final connectivity. DXF, RAW and BO object file formats are summarized below.


Figure 6. 3D Object file formats summary.

Figure 6 below explains the concept on a different object. You can see that various combinations of polygons are selected for connectivity.


Figure 7. Alternatives for wireframe generation.

Once an appropriate format for mesh generation is selected, it can be exported to rendering module to produce visually appealing image.


Figure 8. Rendered mesh alternative.

4. My Face

Let's see how my face looked like upon extraction of vector information.


Figure 9. My face as Wireframe extracted from video.

I exported my face wireframe to various applications for rendering. Bryce3D, for example, is shown below.


Figure 10. Bryce 3D renders my face Wireframe.

AutoCAD, 3D Studio MAX also produce high quality rendering output.

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•Ðuchit