931 research outputs found

    Engineering data compendium. Human perception and performance. User's guide

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    The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

    Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 156)

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    This bibliography lists 170 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1976

    Using cross-talk simulation to predict the performance of anaglyph 3-D glasses

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    The anaglyph 3-D method is a widely used technique for presenting stereoscopic 3-D images. Its primary advantage is that it will work on any full-color display (LCDs, plasmas, and even prints) and only requires that the user view the anaglyph image using a pair of anaglyph 3-D glasses with usually one lens tinted red and the other lens tinted cyan (blue plus green). A common image-quality problem of anaglyph 3-D images is high levels of cross-talk — the incomplete isolation of the left and right image channels such that each eye sees a “ghost” of the opposite perspective view. An anaglyph cross-talk simulation model has been developed which allows the amount of anaglyph cross-talk to be estimated based on the spectral characteristics of the anaglyph glasses and the display. The model is validated using a visual cross-talk ranking test which indicates good agreement. The model is then used to consider two scenarios for the reduction of cross-talk in anaglyph systems and finds that a considerable reduction is likely to be achieved by using spectrally pure displays. The study also finds that the 3-D performance of commercial anaglyph glasses can be significantly better than handmade anaglyph glasses

    Automatic Bluefin Tuna Sizing with a Combined Acoustic and Optical Sensor

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    [EN] A proposal is described for an underwater sensor combining an acoustic device with an optical one to automatically size juvenile bluefin tuna from a ventral perspective. Acoustic and optical information is acquired when the tuna are swimming freely and the fish cross our combined sensor's field of view. Image processing techniques are used to identify and classify fish traces in acoustic data (echogram), while the video frames are processed by fitting a deformable model of the fishes' ventral silhouette. Finally, the fish are sized combining the processed acoustic and optical data, once the correspondence between the two kinds of data is verified. The proposed system is able to automatically give accurate measurements of the tuna's Snout-Fork Length (SFL) and width. In comparison with our previously validated automatic sizing procedure with stereoscopic vision, this proposal improves the samples per hour of computing time by 7.2 times in a tank with 77 juveniles of Atlantic bluefin tuna (Thunnus thynnus), without compromising the accuracy of the measurements. This work validates the procedure for combining acoustic and optical data for fish sizing and is the first step towards an embedded sensor, whose electronics and processing capabilities should be optimized to be autonomous in terms of the power supply and to enable real-time processing.This work was supported by funding from ACUSTUNA project ref. CTM2015-70446-R (MINECO/ERDF, EU) and PAID-10-19 (UPV).Muñoz-Benavent, P.; Puig Pons, V.; Andreu García, G.; Espinosa Roselló, V.; Atienza-Vanacloig, V.; Pérez Arjona, I. (2020). Automatic Bluefin Tuna Sizing with a Combined Acoustic and Optical Sensor. Sensors. 20(18):1-17. https://doi.org/10.3390/s20185294S117201

    Automatic Bluefin Tuna sizing using a stereoscopic vision system

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    [EN] This article presents a non-invasive fully automatic procedure for Bluefin Tuna sizing, based on a stereoscopic vision system and a deformable model of the fish ventral silhouette. An image processing procedure is performed on each video frame to extract individual fish, followed by a fitting proce- dure to adjust the fish model to the extracted targets, adapting it to the bending movements of the fish. The proposed system is able to give accu- rate measurements of tuna snout fork length (SFL) and widths at five predefined silhouette points without manual intervention. In this work, the system is used to study size evolution in adult Atlantic Bluefin Tuna (Thunnus Thynnus) over time in a growing farm. The dataset is composed of 12 pairs of videos, which were acquired once a month in 2015, between July and October, in three grow-out cages of tuna aquaculture facilities on the west Mediterranean coast. Each grow out cage contains between 300 and 650 fish on an approximate volume of 20 000 m3.Measurements were au- tomatically obtained for the 4 consecutive months after caging and suggest a fattening process: SFL shows an increase of just a few centimetres (2%) while themaximum width (A1)shows arelative increaseofmorethan20%,mostlyinthe first 2months in farm. Moreover, a linear relation (with co- efficient of determination R2> 0.98) between SFL and widths for each month is deduced, and a fattening factor (F) is introduced. The validity of the measurements is proved by comparing 15 780 SFL measurements, obtained with our automatic system in the last month, versus ground truth data of a high percentage of the stock under study (1143 out of 1579), obtaining no statistically significant difference. This procedure could be extended to other species to assess the size distribution of stocks, as discussed in the article.This work was supported by funding from ACUSTUNA project ref. CTM2015-70446-R (MINECO/ERDF, EU). This project has been possible thanks to the collaboration of IEO (Spanish Oceanographic Institute).Muñoz-Benavent, P.; Andreu García, G.; Valiente González, JM.; Atienza-Vanacloig, V.; Puig Pons, V.; Espinosa Roselló, V. (2018). Automatic Bluefin Tuna sizing using a stereoscopic vision system. ICES Journal of Marine Science. 75(1):390-401. https://doi.org/10.1093/icesjms/fsx151S39040175

    3D Visualization using virtual view generation for stereoscopic hardware

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    To summarize, the final purpose is to create a compact tool that generates virtual stereo views at a desired position, being able to move and rotate it, from the information of several cameras spread in the area. These views will allow to visualize the scene in 3D, using a device that reproduces the stereoscopic effect, from the current point of vie

    Enhanced fish bending model for automatic tuna sizing using computer vision

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    [EN] This paper presents a non-invasive fully automatic procedure to obtain highly accurate fish length estimation in adult Bluefin Tuna, based on a stereoscopic vision system and a deformable model of the fish ventral silhouette. The present work takes a geometric tuna model, which was previously developed by the same authors to discriminate fish in 2D images, and proposes new models to enhance the capabilities of the automatic procedure, from fish discrimination to accurate 3D length estimation. Fish length information is an important indicator of the health of wild fish stocks and for predicting biomass using length-weight relations. The proposal pays special attention to parts of the fish silhouette that have special relevance for accurate length estimation. The models have been designed to best fit the rear part of the fish, in particular the caudal peduncle, and a width parameter has been added to better fit the silhouette. Moreover, algorithms have been developed to extract snout tip and caudal peduncle features, allowing better initialization of model parameters. Snout Fork Length (SFL) measurements using the different models are extracted from images recorded with a stereoscopic vision system in a sea cage containing 312 adult Atlantic Bluefin Tuna. The automatic measurements are compared with two ground truths: one configured with semiautomatic measurements of favourable selected samples and one with real SFL measurements of the tuna stock collected at harvesting. Comparison with the semiautomatic measurements demonstrates that the combination of improved geometric models and feature extraction algorithms delivers good results in terms of fish length estimation error (up to 90% of the samples bounded in a 3% error margin) and number of automatic measurements (up to 950 samples out of 1000). When compared with real SFL measurements of the tuna stock, the system provides a high number of automatic detections (up to 6706 in a video of 135¿min duration, i.e., 50 automatic measurements per minute of recording) and highly accurate length measurements, obtaining no statistically significant difference between automatic and real SFL frequency distributions. This procedure could be extended to other species to assess the size distribution of stocks, as discussed in the paper.This work was supported by funding from ACUSTUNA project ref. CTM2015-70446-R (MINECO/ERDF, EU). This project has been possible thanks to the collaboration of IEO (Spanish Oceanographic Institute). We acknowledge the assistance provided by the Spanish company Grup Balfego S.L. in supplying boats and divers to acquire underwater video in the Mediterranean Sea.Muñoz-Benavent, P.; Andreu García, G.; Valiente González, JM.; Atienza-Vanacloig, V.; Puig Pons, V.; Espinosa Roselló, V. (2018). Enhanced fish bending model for automatic tuna sizing using computer vision. Computers and Electronics in Agriculture. 150:52-61. https://doi.org/10.1016/j.compag.2018.04.005S526115

    A Conservation plan for the Juan Mendez photographic collection

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    This thesis is put forth to document not only the outcome of two years worth of intensive investigation and preparation on the Juan Mendez Photographic Collection, but more importantly it offer viable conservation measures. The first two chapters describe the context of the life and work of Juan Mendez, a Mexican photographer who was active in the City of Puebla, Mexico during the years of 1926 to 1962. The third and fourth chapters are a report of the conservation survey that took place through various visits to the collection of his works during the course of one year. With the results obtained through this survey, a plan of action is suggested to formulate an integral conservation strategy for the collection. Finally, the appendix contains charts, drawings and a bibliography. This document functions as a tool that could be an integral model for preservation of the iconographic holdings of the Juan Mendez photographic archives
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