Object Identification Using Bar Codes Based of LADAR Intensity

Abstract

Tests of a novel concept for tracking construction components were carried out at the National Institute of Standards and Technology. The approach makes use of laser radar and retro-reflective barcodes attached to manufactured building materials. Tests were conducted for various barcode sizes and spacings through a variety of ranges to a maximum of 40 m. At 40 m, it was possible to infer one byte of information content in a 1D barcode measuring 575 mm (22.6 in.) in length with no special optical processing for a LADAR instrument with an aperture beam diameter of 25 mm and a beam divergence of 2.7 mrad. Simple thresholding post-processing techniques were employed to study the resulting intensity data and to deduce minimum detectable bar gap spacing. These analyses have suggested paths to significant resolution enhancements based on image processing and optical physics simulation techniques.

Reconstructing Images of Bar Codes for Construction Site Object Recognition

“…From measured images, it was determined that the intensity of the return signal of the board on which the bars were mounted was approximately 150 and the intensity levels of the bars were approximately 250. Simulated ground truth data files were created for three sets of barcodes (see ISARC 2001 [1]) with an example of 25.4 mm (1 in) bars shown in Figure 5. Based upon the measurements of the beam spread function three beam matrices were created to represent the spread function at 10 m, 20 m, and 40 m. Since it was difficult to obtain a precise measurement of the beam spread function, matrices representing the three spatial beam spread configurations were created.…”

“…The same 1 Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States method could also be used to identify objects within a construction scene. This would involve using the LADAR to "read" a bar code.…”

“…At ISARC 2001 [1] methods of determining the appropriate material for the bar codes and determining if the use of bar codes was viable were reported. The results from these efforts showed that at distances beyond 20 m, the intensity images were too blurred to be readable and that image processing techniques were necessary to reconstruct the image.…”

Integration of Automated Data Collection Technologies for Real-Time Field Materials Management

“…NIST conducts a research for establishing standards to support identification and tracking of construction components by means of different sensing technologies, such as barcodes, radio frequency identification devices, and global positioning systems (GPS) [15]. Finally, Stone et al merged laser detection and ranging (LADAR's) with barcode technology in order to read the materials' identification labels at maximum distances between 30 and 40 meters [16].…”