A Four-Head Color Laser Range Scanner

A. Ardeshir Goshtasby

(funded by NSF and OBR)


Programmer Assistants:
Aaron Knapp & Jon Knapp

This project develops a four-head scanner system that will obtain a surround image of an object and reconstruct the object in 3-D. Each camera head is equipped with a camera and a laser line generator. The four camera heads move together during scanning. The laser images from the four cameras are processed to obtain the 3-D structure of the object. Since the images contain color information, they are used as textures to paint the reconstructed object. The reconstructed and painted object are then used in an animation project.

 

The Hardware of the scanner.


Images captures by the four cameras at a given time frame:

 

Results

 

These images were obtained using the laser scanner on a representation of the head of Alexander the Great. The 3D range data was generated using Open Inventor for SGI O2 machines. Images from three of the cameras were color corrected. Image from one of the cameras was not changed.

Additional Images will be posted as they become available.

 

 

This is an example of a generated model.

 


 

Methods

 

 

The software for this scanner was developed in Unix on SGI O2 hardware. There are several components which make up the completed software package. Following are the components along with the primary task and a brief explaination of their operation.

 

  1. AJKCapture

This program captures syncronous video from the four cameras. It is important that the captured movie files have frames captured at the same time. Otherwise, the finished model will not be properly lined up.

  • AJKScan
  • This program takes the raw movie files and gathers range data for the model. Since the coordinates inside the scanner are fixed, we can use the position of the laser's line in each frame to find the corresponding position in the scanner's Real World Coordinates. The result of running this program is a range data file and a texture image.

  • AJKFit
  • The data obtained from AJKScan is an unordered list of range data. To be able to display this data as a model, it must be transforned into a regular grid. AJKFit takes the unordered data and uses it to construct a model that 3D applications will be able to interpret. Currently, AJKFit can create models for Open Inventor and DFX, a widely used Autocad 3D model format. With this feature to export to DFX files, the models obtained from this scanner can be displayed on virtually any computer system.

  • AJKDraw AJKDraw is simply responsible for displaying the model generated from AJKFit along with the texture from AJKScan. It uses Open Inventor for this task.
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     Here is a sample data set from this scanner.

    An algorithm developed by Jim Albamont as a part of his M.S. thesis uses a virtual laser instead of a real one under the same setup to capture surround range data from an object.


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    For more information please contact A. Goshtasby (agoshtas@cs.wright.edu).