Laser Scanning, Rangefinding and Flash Profiling

Acuity Technologies has 2 types of active (projected light) shape capture technology. One is based on scanning laser rangefinding (LADAR), the other on projective geometry and structured light photogrammetry. Our scanners work at ranges up to 600 meters. The stuctured light projection systems have ranges up to 10 meters and can capture several million 3D points in a single laser flash.

SRI-500 Scanning Rangefinding Imager

        Acuity's SRI-500 imaging laser rangefinder uses a unique single-mirror scanning system to obtain scans up to 360 degrees by 130 degrees in less than a second. Sample rates are up to 800,000 points per second with range to 150 meters, or 200,000 samples per second to 600 meters. Short range systems have an accuracy of 50 mm, while the longer range systems are accurate to 100 mm.

Additional product information.

 

        Above, a 360 degree scan of a simulated crime scene was scanned with an Acuity AR4000 and scanner. Below, the points obtained are reduced to a triangular mesh. The data is then overlaid with a color photo taken from the same viewpoint as the depth map scan. Below right, a new virtual viewpoint has been generated and rendered from the combined depth map and image data. Photos courtesy of 3rdTech.

Polygon Mesh from Scan
Mesh with Color Image Data
A Synthetic Perspective

Laser Flash 3D Imaging - Structured Light Photogrammetry

        By projecting a pattern of light on an object and imaging it from multiple directions, many points on the object can be identified and resolved in 3-space. This approach can be used to resolve over 1 million 3D points on objects ranging in size from a few millimeters to 10 meters across from a single photograph with exposure times down to 1 microsecond. This enables real-time 3D capture of complex transient and vibratory deflections and motion. The high accuracy of conventional photogrammetry can be attained without targets, at unprecedented point densities. A white paper describing an aircraft suface mapping application can be found here.

Snapshot Surface Mapping

        Acuity has developed a capture system for field and industrial capture of surface contours and discontinuous shapes. The system has accuracy of 0.01 inch or better at over 1 million points distributed over a region 100 inches across from two or more images obtained with a high resolution handheld digital camera. A tripod or permanently mounted projector projects a pattern onto the surface from which the point positions can be derived. This can be moved to allow capture of different overlapping areas which can be combined into a single surface representation. The working envelope of the system is from less than 10 inches to beyond 500 inches, with accuracy proportional to the distance from the camera to the surface.

Gasifier Furnace Profilometry

        Acuity Technologoes is prototyping a profiler for gasification furnaces under a Dept. of Energy contract won by Process Metrix, a developer of equipment for the steel and chemical industries. Process Metrix has contracted with Acuity to develop components of a system capable of obtaining fast profiles of furnaces at operating temperatures. These profiles are necessary to monitor ablation of the furnace wall during use without cooling the furnace, which can take several days. This application requires fast capture in an extreme environment though a small aperture.

Other Applications

        Acuity’s equipment is used by Sierra Pacific Industries to create 3D maps of logs for cut optimization. Large mills process up to 30 logs per minute, and accurate scanning is required to maximize the use of raw material without slowing throughput. A sample log map created with the AR4000 and 4000 Scanner is shown at right.
1998: Acuity develops a rangefinder for JPL for their work in the DARPA Tactical Mobile Robotics Program, shown at right with the JPL scanning mirror system.

In 1994 CMU’s Field Robotics Lab selected Acuity’s AR3000 for the primary ranging imaging vision system for path planning on Dante II, a hexapod walking robot. The AR3000 is visible at the top of Dante, pictured at left in a crater on Mt. Spurr, Alaska.