Aladdin's Magic Lamp: Developing Methods for Calibration and Geolocation Accuracy Assessment of the DMSP OLS

Nighttime satellite imagery from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has a unique capability to observe nocturnal light emissions from sources including cities, wild fires, and gas flares. Data from the DMSP OLS is used in a wide range of studies including mapping urban areas, estimating informal economies, and estimating urban populations. Given the extensive and increasing list of applications a repeatable method for assessing geolocation accuracy, performing inter-calibration, and defining the minimum detectable brightness would be beneficial. An array of portable lights was designed and taken to multiple field sites known to have no other light sources. The lights were operated during nighttime overpasses by the DMSP OLS and observed in the imagery. A first estimate of the minimum detectable brightness is presented based on the field experiments conducted. An assessment of the geolocation accuracy was performed by measuring the distance between the GPS measured location of the lights and the observed location in the imagery. A systematic shift was observed and the mean distance was measured at 2.9km. A method for in situ radiance calibration of the DMSP OLS using a ground based light source as an active target is presented. The wattage of light used by the active target strongly correlates with the signal measured by the DMSP OLS. This approach can be used to enhance our ability to make inter-temporal and inter-satellite comparisons of DMSP OLS imagery. Exploring the possibility of establishing a permanent active target for the calibration of nocturnal imaging systems is recommended. The methods used to assess the minimum detectable brightness, assess the geolocation accuracy, and build inter-calibration models lay the ground work for assessing the energy expended on light emitted into the sky at night. An estimate of the total energy consumed to light the night sky globally is presented.

Resolution limits to object tracking with subpixel accuracy

Subpixel methods increase the accuracy and efficiency of image detectors, processing units, and algorithms and provide very cost-effective systems for object tracking. Published methods achieve resolution increases up to three orders of magnitude. In this Letter, we demonstrate that this limit can be theoretically improved by several orders of magnitude, permitting micropixel and submicropixel accuracies. The necessary condition for movement detection is that one single pixel changes its status. We show that an appropriate target design increases the probability of a pixel change for arbitrarily small shifts, thus increasing the detection accuracy of a tracking system. The proposal does not impose severe restriction on the target nor on the sensor, thus allowing easy experimental implementation.

Repeatability, reproducibility, and accuracy of a novel pushbroom hyperspectral system

This study analyzes the repeatability, reproducibility and accuracy of a new hyperspectral system based on a pushbroom sensor as a means of measuring spectral features and color of materials and objects. The hyperspectral system consisted of a CCD camera, a spectrograph and an objective lens. An additional linear moving system allowed the mechanical scanning of the complete scene. A uniform overhead luminaire with daylight configuration was used to irradiate the scene using d:45 geometry. We followed the guidelines of the ASTM E2214-08 Standard Practice for Specifying and Verifying the Performance of Color-Measuring Instruments that define the standards and latest multidimensional procedures. The results obtained are analyzed in-depth and compared to those recently reported by other authors for spectrophotometers and multispectral systems. It can be concluded that hyperspectral systems are reliable and can be used in the industry to perform spectral and color readings with a high spatial resolution.

Three-dimensional planar object tracking with sub-pixel accuracy

Subpixel techniques are commonly used to increase the spatial resolution in tracking tasks. Object tracking with targets of known shape permits obtaining information about object position and orientation in the three-dimensional space. A proper selection of the target shape allows us to determine its position inside a plane and its angular and azimuthal orientation under certain limits. Our proposal is demonstrated both numerical and experimentally and provides an increase the accuracy of more than one order of magnitude compared to the nominal resolution of the sensor. The experiment has been performed with a high-speed camera, which simultaneously provides high spatial and temporal resolution, so it may be interesting for some applications where this kind of targets can be attached, such as vibration monitoring and structural analysis.

Accuracy and sensitivity of CRASH.

Mode of access: Internet.

Precision and accuracy assessments for state and local air monitoring networks, 1981-1986 /

Mode of access: Internet.

Evaluation and research program of the U.S. censuses of population and housing, 1960 : accuracy of data on housing characteristics.

Mode of access: Internet.

Evaluation and research program of the U.S. censuses of population and housing, 1960 : accuracy of data on population characteristics as measured by reinterviews.

Mode of access: Internet.

Evaluation and research program of the U.S. censuses of population and housing, 1960 : accuracy of data on population characteristics for subgroups of the total population.

Bibliography: p. 76.

Analysis of missile trajectory measurement accuracy for data processing

"Contract no. AF 30(602)-2138, Project 5554, Task 55102."

Study of the effects of turnout design on registration accuracy of propeller meters placed in downstream ends of turnout pipes /

Mode of access: Internet.

The accuracy of present wave forecasting methods : with reference to problems in beach erosion on the New Jersey and Long Island coasts /

Mode of access: Internet.

Accuracy of hydrographic surveying in and near the surf zone /

Mode of access: Internet.

English grammar, adapted to the different classes of learners : with an appendix, containing rules and observations for assisting the more advanced students to write with perspicuity and accuracy /

On spine: Murray's grammar.

English grammar, adapted to the different classes of learners : with an appendix, containing rules and observations for assisting the more advanced students to write with perspicuity and accuracy /

At head of title: Stereotype edition.