Recovering 3D Geometry using a Robot Arm and a Laser Scanner
James Kuffner, Jr.

Spring 1994

Project Overview : The goal of this project is to reconstruct the 3D geometry of a static object.  Scanning devices that use rotating or translating platforms can only scan relatively small movable objects, and typically must make multiple scans and combine the data as a post-process.   Mounting the scanner on a controlled robot provides a means for scanning larger objects in a single pass.  In addition, objects which cannot be moved (such as building facades) can also be scanned.

Concept : Given a robot with a device that emits a plane of laser light, the idea is to sweep the plane of light across the surface of the object and view the profile of the object contour using an off-axis CCD camera mounted near the laser. The resulting camera images can be used to compute the 3D coordinates of points on the object surface via triangulation.

Final Report: Download a gzipped postscript file (15 pages = 139K).

Software: Four original C programs constituted the bulk of the project effort.

	A program to correct for camera image distortion.
	A program to interpret the camera images and output 3D coordinates of the object surface.
	A program to take a set of 3D coordinates and output a triangular mesh corresponding to a surface that fits the data points.
	Finally, a visualization program written for the SGI that allows a user to interactively view the triangular mesh of the original scanned object.

Work Schedule : The project was completed in approximately five weeks. Three main work phases were involved: [Equipment setup, testing, and data collection (1.5 weeks), Data interpretation software (2.5 weeks), Mesh visualization software (1 week)].

Other References: Standard calibration algorithms presented in class and in the textbook were used, as well as notes on triangulation and mesh-generation from 3D data points (specifically: Drushel, R F. Survey of methods for 3-dimensional reconstruction" comp.graphics.visualization: Usenet, 1993)