Point Clouds

What is a point cloud?

A point cloud is just a bunch of points. Although it is sometimes useful to talk about point clouds in any dimensional space, we usually care only about 3D.

Why should I care about point clouds?

So you can impress your friends.

Huh?

Suppose you wanted to make a cool-looking 3D computer model of your new convertible, to put on your web site. This will definitely impress your friends, unless you live in Palo Alto or Northwest Austin, where all of your friends own more expensive cars than you. You can do this by first making a 3D point cloud model of your car, and then turning this point cloud into a cool-looking 3D computer model of your car.

So how would I make a 3D point cloud model of my car?

The best way is probably to take a laser range scanner which shoots laser rays at various points on the car and records the distance from the scanner to each point. This gives you a bunch of data points, each point representing a specific position on the car in 3D space.

Where on earth would I get a laser range scanner?

I recommend entering a Ph.D. program in computer graphics at a university that owns a laser range scanner.

OK. Now how do I turn this ugly point cloud into a cool-looking 3D computer model?

Actually, even top-level researchers don't know how to do this well. Researchers are trying to come up with computer programs that can take any point cloud and turn it into a picture with nice smooth surfaces. They also want these programs to run quickly. This problem of making smooth surfaces from a point cloud is known as surface reconstruction.

But researchers can't afford fancy cars! Why would they ever care about point clouds?

Those researchers who aren't interested in fancy cars, have many other reasons to care about point clouds. Here is a list of some areas where point clouds can be useful.

  1. Geometric/solid modeling
    1. Laser range scanner data
    2. Hand-held digitizer data
    3. Geoscience: terrain modeling
  2. Industrial applications
    1. Reverse engineering
    2. Product design
    3. Construction of personal medical appliances
  3. Computer graphics
  4. CAGD
  5. Medical imaging
    1. CT scan data
    2. MRI scan data
    3. Protein modeling
  6. Digital film-making
  7. Shape analysis
  8. Virtual worlds authoring
  9. 3D faxing
  10. Tailor-fit modeling
  11. Cosmetics

So what have researchers done with point clouds so far?

This page contains my summaries of some papers researchers have written about point clouds: