A proposed optoelectronic system, to be mounted aboard an exploratory robotic vehicle, would be used to generate a three-dimensional (3D) map of nearby terrain and obstacles for purposes of navigating the vehicle across the terrain and avoiding the obstacles. Like some other systems that have been, variously, developed and proposed to perform similar functions, this system would include (1) a light source that would project a known pattern of bright spots onto the terrain, (2) an electronic camera that would be laterally offset from the light source by a known baseline distance, (3) circuitry to digitize the output of the camera during imaging of the light spots, and (4) a computer that would calculate the 3D coordinates of the illuminated spots from their positions in the images by triangulation.
The difference between this system and the other systems would lie in the details of implementation. In this system, the illumination would be provided by a laser. The beam from the laser would pass through a two-dimensional diffraction grating, which would divide the beam into multiple beams propagating in different, fixed, known directions (see figure). These beams would form a grid of bright spots on the nearby terrain and obstacles. The centroid of each bright spot in the image would be computed. For each such spot, the combination of (1) the centroid, (2) the known direction of the light beam that produced the spot, and (3) the known baseline would constitute sufficient information for calculating the 3D position of the spot.
Concentrating the illumination into spots, instead of into lines as in some other systems, would afford signal-tonoise ratios greater than those of such other systems and would thereby also enable this system to image terrain and obstacles out to greater distances. The laser could be pulsed to obtain momentary illumination much brighter than ambient illumination, and the camera could be synchronized with the laser to discriminate against ambient light between laser pulses.
This work was done by Curtis Padgett, Carl Liebe, Johnny Chang, and Kenneth Brown of Caltech for NASA's Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Electronics/Computers category. NPO-40611
This Brief includes a Technical Support Package (TSP).
Mapping Nearby Terrain in 3D By Use of a Grid of Laser Spots
(reference NPO-40611) is currently available for download from the TSP library.
Don't have an account?
Overview
The document is a Technical Support Package from NASA’s Jet Propulsion Laboratory (JPL) detailing advancements in 3D terrain mapping using a grid of laser spots, referenced as NPO-40611 in NASA Tech Briefs. This technology aims to enhance the capabilities of spacecraft in hazard avoidance and terrain analysis, which are critical for safe navigation and exploration.
The primary focus of the document is on the innovative use of structured light for three-dimensional imaging. Structured light involves projecting a known pattern of light onto a surface and analyzing the deformation of that pattern to extract depth information. This technique is particularly useful in environments where traditional imaging methods may be limited or ineffective.
The document references several key publications and presentations related to this technology, including works by authors such as Liebe, Padgett, and others, presented at the IEEE Aerospace Conference in 2004 and 2006. These references provide further insights into the methodologies and applications of structured light in aerospace contexts, emphasizing its potential for improving spacecraft navigation and environmental interaction.
Additionally, the Technical Support Package outlines the broader implications of this technology beyond aerospace, suggesting its applicability in various scientific and commercial fields. The document encourages collaboration and innovation through NASA's Commercial Technology Program, which aims to disseminate aerospace-related developments for wider technological and scientific use.
For those seeking further information or assistance, the document provides contact details for the Innovative Technology Assets Management at JPL, inviting inquiries related to research and technology in this area.
Overall, the document serves as a resource for understanding the advancements in 3D imaging technologies, particularly through the use of structured light, and highlights NASA's commitment to fostering innovation that can benefit multiple sectors. It underscores the importance of these technologies in enhancing the safety and efficiency of space exploration while also paving the way for their application in other domains.
