4,014 research outputs found
Infrared face recognition: a comprehensive review of methodologies and databases
Automatic face recognition is an area with immense practical potential which
includes a wide range of commercial and law enforcement applications. Hence it
is unsurprising that it continues to be one of the most active research areas
of computer vision. Even after over three decades of intense research, the
state-of-the-art in face recognition continues to improve, benefitting from
advances in a range of different research fields such as image processing,
pattern recognition, computer graphics, and physiology. Systems based on
visible spectrum images, the most researched face recognition modality, have
reached a significant level of maturity with some practical success. However,
they continue to face challenges in the presence of illumination, pose and
expression changes, as well as facial disguises, all of which can significantly
decrease recognition accuracy. Amongst various approaches which have been
proposed in an attempt to overcome these limitations, the use of infrared (IR)
imaging has emerged as a particularly promising research direction. This paper
presents a comprehensive and timely review of the literature on this subject.
Our key contributions are: (i) a summary of the inherent properties of infrared
imaging which makes this modality promising in the context of face recognition,
(ii) a systematic review of the most influential approaches, with a focus on
emerging common trends as well as key differences between alternative
methodologies, (iii) a description of the main databases of infrared facial
images available to the researcher, and lastly (iv) a discussion of the most
promising avenues for future research.Comment: Pattern Recognition, 2014. arXiv admin note: substantial text overlap
with arXiv:1306.160
Face recognition technologies for evidential evaluation of video traces
Human recognition from video traces is an important task in forensic investigations and evidence evaluations. Compared with other biometric traits, face is one of the most popularly used modalities for human recognition due to the fact that its collection is non-intrusive and requires less cooperation from the subjects. Moreover, face images taken at a long distance can still provide reasonable resolution, while most biometric modalities, such as iris and fingerprint, do not have this merit. In this chapter, we discuss automatic face recognition technologies for evidential evaluations of video traces. We first introduce the general concepts in both forensic and automatic face recognition , then analyse the difficulties in face recognition from videos . We summarise and categorise the approaches for handling different uncontrollable factors in difficult recognition conditions. Finally we discuss some challenges and trends in face recognition research in both forensics and biometrics . Given its merits tested in many deployed systems and great potential in other emerging applications, considerable research and development efforts are expected to be devoted in face recognition in the near future
Crop Disease Detection Using Remote Sensing Image Analysis
Pest and crop disease threats are often estimated by complex changes in crops and the applied agricultural practices that result mainly from the increasing food demand and climate change at global level. In an attempt to explore high-end and sustainable solutions for both pest and crop disease management, remote sensing technologies have been employed, taking advantages of possible changes deriving from relative alterations in the metabolic activity of infected crops which in turn are highly associated to crop spectral reflectance properties. Recent developments applied to high resolution data acquired with remote sensing tools, offer an additional tool which is the opportunity of mapping the infected field areas in the form of patchy land areas or those areas that are susceptible to diseases. This makes easier the discrimination between healthy and diseased crops, providing an additional tool to crop monitoring. The current book brings together recent research work comprising of innovative applications that involve novel remote sensing approaches and their applications oriented to crop disease detection. The book provides an in-depth view of the developments in remote sensing and explores its potential to assess health status in crops
Earth observations from space: Outlook for the geological sciences
Remote sensing from space platforms is discussed as another tool available to geologists. The results of Nimbus observations, the ERTS program, and Skylab EREP are reviewed, and a multidisciplinary approach is recommended for meeting the challenges of remote sensing
Development of a Multimode Instrument for Remote Measurements of Unsaturated Soil Properties
The hydromechanical behavior of soil is governed by parameters that include the moisture content, soil matric potential, texture, and the mineralogical composition of the soil. Remote characterization of these and other key properties of the soil offers advantages over conventional in situ or laboratory-based measurements: information may be acquired rapidly over large, or inaccessible areas; samples do not need to be collected; and the measurements are non-destructive. A field-deployable, ground-based remote sensor, designated the Soil Observation Laser Absorption Spectrometer (SOLAS), was developed to infer parameters of bare soils and other natural surfaces over intermediate (100 m) and long (1,000 m) ranges.
The SOLAS methodology combines hyperspectral remote sensing with differential absorption and laser ranging measurements. A transmitter propagates coherent, near-infrared light at on-line (823.20 nm) and off-line (847.00 nm) wavelengths. Backscattered light is received through a 203-mm diameter telescope aperture and is divided into two channels to enable simultaneous measurements of spectral reflectance, differential absorption, and range to the target. The spectral reflectance is measured on 2151 continuous bands that range from visible (380 nm) to shortwave infrared (2500 nm) wavelengths. A pair of photodetectors receive the laser backscatter in the 820–850 nm range. Atmospheric water vapor is inferred using a differential absorption technique in conjunction with an avalanche photodetector, while range to the target is based on a frequency-modulated, self-chirped, homodyne detection scheme.
The design, fabrication, and testing of the SOLAS is described herein. The receiver was optimized for the desired backscatter measurements and assessed through a series of trials that were conducted in both indoor and outdoor settings. Spectral reflectance measurements collected at proximal range compared well with measurements collected at intermediate ranges, demonstrating the utility of the receiver. Additionally, the noise characteristics of the spectral measurements were determined across the full range of the detected wavelengths. Continued development of the SOLAS instrument will enable range-resolved and water vapor-corrected reflectance measurements over longer ranges. Anticipated applications for the SOLAS technology include rapid monitoring of earth construction projects, geohazard assessment, or ground-thruthing for current and future satellite-based multi- and hyperspectral data
Application of remote sensing to selected problems within the state of California
There are no author-identified significant results in this report
Multispectral Imaging For Face Recognition Over Varying Illumination
This dissertation addresses the advantage of using multispectral narrow-band images over conventional broad-band images for improved face recognition under varying illumination. To verify the effectiveness of multispectral images for improving face recognition performance, three sequential procedures are taken into action: multispectral face image acquisition, image fusion for multispectral and spectral band selection to remove information redundancy.
Several efficient image fusion algorithms are proposed and conducted on spectral narrow-band face images in comparison to conventional images. Physics-based weighted fusion and illumination adjustment fusion make good use of spectral information in multispectral imaging process. The results demonstrate that fused narrow-band images outperform the conventional broad-band images under varying illuminations. In the case where multispectral images are acquired over severe changes in daylight, the fused images outperform conventional broad-band images by up to 78%. The success of fusing multispectral images lies in the fact that multispectral images can separate the illumination information from the reflectance of objects which is impossible for conventional broad-band images.
To reduce the information redundancy among multispectral images and simplify the imaging system, distance-based band selection is proposed where a quantitative evaluation metric is defined to evaluate and differentiate the performance of multispectral narrow-band images. This method is proved to be exceptionally robust to parameter changes.
Furthermore, complexity-guided distance-based band selection is proposed using model selection criterion for an automatic selection. The performance of selected bands outperforms the conventional images by up to 15%. From the significant performance improvement via distance-based band selection and complexity-guided distance-based band selection, we prove that specific facial information carried in certain narrow-band spectral images can enhance face recognition performance compared to broad-band images. In addition, both algorithms are proved to be independent to recognition engines.
Significant performance improvement is achieved by proposed image fusion and band selection algorithms under varying illumination including outdoor daylight conditions. Our proposed imaging system and image processing algorithms lead to a new avenue of automatic face recognition system towards a better recognition performance than the conventional peer system over varying illuminations
Biometric Spoofing: A JRC Case Study in 3D Face Recognition
Based on newly available and affordable off-the-shelf 3D sensing, processing and printing technologies, the JRC has conducted a comprehensive study on the feasibility of spoofing 3D and 2.5D face recognition systems with low-cost self-manufactured models and presents in this report a systematic and rigorous evaluation of the real risk posed by such attacking approach which has been complemented by a test campaign. The work accomplished and presented in this report, covers theories, methodologies, state of the art techniques, evaluation databases and also aims at providing an outlook into the future of this extremely active field of research.JRC.G.6-Digital Citizen Securit
Applications of remote sensing in sugarcane agriculture at Umfolozi, South Africa.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.The aim of this study was to evaluate potential applications of remote sensing technology in sugarcane agriculture, using the Umfolozi Mill Supply Area as a case study. Several objectives included the
evaluation of remotely sensed satellite information for the following applications: mapping of
sugarcane areas, identifying sugarcane characteristics including phenology, cultivar and yield,
monitoring the sugarcane inventory throughout the milling season and yield prediction.
Four Landsat 7 ETM+ (Enhanced Thematic Mapper Plus) images were obtained for the 2001-2002
season. Mapping of sugarcane areas was conducted by .means of unsupervised hierarchical
classifications, on three relatively cloud free, Tasseled Cap transformed images. The Brightness,
Greenness and Wetness bands for each Tasseled Cap transformed image were combined into a
single image for this classification.
The investigation into relationships between satellite spectral reflectances and phenology, cultivar
and yield involved the cosine of the solar zenith angle (COST) method for atmospheric correction
of all four Landsat 7 ETM+ images. Detailed agronomic records and field boundary information,
for a selection of sugarcane fields, were used to extract the at-satellite reflectances on a pixel basis .
These values were stored in a relational database for analysis.
Monitoring of the sugarcane inventory throughout the milling season was conducted by means of
unsupervised classifications on the Brightness, Greenness and Wetness bands for each of the four
time-step Tasseled Cap transformed images. Accurate field boundary information for all sugarcane
fields was used to mask out non-sugarcane areas. The remaining sugarcane areas in each time-step
image were then classified by means of unsupervised classification techniques to ascertain the relative
proportions of the different land covers, namely: harvested immature and mature sugarcane by visual
interpretation of the classification results.
The yield forecasting approach utilized a time-step approach in which Vegetation Indices (VIs) were
accumulated over different periods or time frames and compared with annual production. VIs were
derived from both the National Oceanic and Atmospheric Administration (NOAA) and Landsat 7
ETM+ sensors. Different periods or times were used for each sensor.
The results for the mapping of sugarcane areas showed that the mapping accuracies for the large scale
grower fields was higher than for the small-scale growers. In both instances, the level of
accuracy was below that of the recommended sugar industry mapping standard, namely 1% of the
true area. Despite the low mapping accuracies, much benefit could be realized from the map product
in terms of identifying new areas of sugarcane expansion. These would require detailed accurate
mapping. The results for monitoring of the sugarcane inventory throughout showed that remote sensing, in
conjunction with detailed field information, was able to accurately measure the areas harvested in
each time-step image. These results may have highly beneficial applications in sugarcane supply
management and monitoring.
The results for time-step approach to yield forecasting yielded poor results in general. The Landsat
derived VIs showed limited potential; however, the data were only available for one season, making
it difficult to quantify the impact of climatic conditions on these results. All results for the time-step
approach using NOAA data yielded negative results.
The results for the investigation into relationships between satellite spectral reflectances and
phenology, cultivar and yield showed that that different phenological stages of sugarcane growth
were identifiable from Landsat 7 ETM+ at-satellite reflectances. The sugarcane yields and cultivar
types were not correlated with the at-satellite reflectances. These results combined with the sugarcane
area monitoring may provide valuable information in the management and monitoring of sugarcane
supply
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