3D Scanning Technology And 3D Modeling Computer Science

1.0 Introduction

This seminar title is discussed about 3D Scanning Technology and 3D Modeling. At the end, I will also choose the most suitable technique to use in my Final Year Project.

Nowadays, 3D technology was approaching us step by step. However, most of the people still do not know that, what is 3D and how they do it? Well, as a good example what kind of 3D that appear in our real life and is so famous recently is 3D movie. I think that most of the youngster or movie chaser watch 3D movie before for sure. For example Avatar 3D, Ice Age 2 3D, Resident Evil: After Life 3D and many others.

However, most of the people do not understand that how does 3D works, and how they create 3D model. In my seminar I would like to introduce different types of 3D modeling, can comparison between them. But for sure, different type of 3D modeling technique are uses in different area. So, I will introduce most of them in this seminar.

Almost all 3D models can be divided into two categories.

Solid - These models define the volume of the object they represent (like a rock). These are more realistic, but more difficult to build. Solid models are mostly used for nonvisual simulations such as medical and engineering simulations, for CAD and specialized visual applications such as ray tracing and constructive solid geometry

Shell/boundary - These models represent the surface. These are easier to work with than solid models. Almost all visual models used in games and film are shell models.

Technology was improved and changes rapidly day by day. A new technology call 3D Digitizing which will use special equipment such as Terrestrial Laser Scanner, 3D Scanner and others was invented. These machines can provides highly accurate, three-dimensional images enabling designers to experience and work directly with real-world conditions by viewing and manipulating rich point-clouds in computer-aided design software. In the chapter below we will go deeper about this technology which was widely used in those fields that involved 3D.

Even many new and advanced type of modeling technique was found, many designer, construction, and others will still use the basic modeling technique, such as Polygonal modeling, NURBS, Splines & Patches modeling, Primitives modeling and Sculpt modeling. In the chapter below, we will explore more about these techniques that are still widely used for those designers and the reason.

Main Body

3D Digitizing

3D Digitizing can be defining as transform the real object (such as a building) to a digitized format. It also can be define as a graphics input system that records x, y and z coordinates of a real object. Contact is made with various points on the object's surface by a light sensor, sound sensor, robotic instrument or pen.

The main device for 3D Digitizing is 3D Scanner which was so popular and most common device that use for 3D Digitizing. 3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly its appearance. The collected data can then be used to construct digital, three dimensional models useful for a wide variety of applications

There were 3 types of 3D Scanner:

- Contact

- Non-contact Active

- Non-contact Passive.

Contact 3D Scanner

As the definition of "contact" which means the 3D Scanner that have physical contact with the object that need to be scan. A CMM (coordinate measuring machine) is a most common example for contact 3D scanner. It is used mostly in manufacturing and can be very precise.

CMM is composed of three axes, an X, Y and Z. These axes are orthogonal to each other in a typical three dimensional coordinate system. Each axis has a scale system that indicates the location of that axis. The machine will read the input from the touch probe, as directed by the operator or programmer. The machine then uses the X, Y, Z coordinates of each of these points to determine size and position. Typical precision of a coordinate measuring machine is measured in Microns.

The disadvantage of CMMs though, is that it requires contact with the object being scanned. Thus, the act of scanning the object might modify or damage it. It was a very serious problem when need to scan with those valuable antique or those artifacts. The other disadvantage of CMMs was time consuming. It may take a long time to finish scan a large or refinement object.

Figure 1 - CMM to scan small object

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