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11.
2-D delineation of individual citrus trees from UAV-based dense photogrammetric surface models 总被引:1,自引:0,他引:1
One of the challenges of remote sensing and computer vision lies in the three-dimensional (3-D) reconstruction of individual trees by using automated methods through very high-resolution (VHR) data sets. However, a successful and complete 3-D reconstruction relies on precise delineation of the trees in two dimensions. In this paper, we present an original approach to detect and delineate citrus trees using unmanned aerial vehicles based on photogrammetric digital surface models (DSMs). The symmetry of the citrus trees in a DSM is handled by an orientation-based radial symmetry transform which is computed in a unique way. Next, we propose an efficient strategy to accurately build influence regions of each tree, and then we delineate individual citrus trees through active contours by taking into account the influence region of each canopy. We also present two efficient strategies to filter out erroneously detected canopy regions without having any height thresholds. Experiments are carried out on eight test DSMs composed of different types of citrus orchards with varying densities and canopy sizes. Extensive comparisons to the state-of-the-art approaches reveal that our proposed approach provides superior detection and delineation performances through supporting a nice balance between precision and recall measures. 相似文献
12.
Aghdam Ali Taheri Salmasi Farzin Abraham John Arvanaghi Hadi 《Geotechnical and Geological Engineering》2021,39(5):3383-3399
Geotechnical and Geological Engineering - The effects of diameter and location of drain pipes on the uplift force and exit hydraulic gradient for a gravity dam are investigated. A numerical model... 相似文献
13.
Acta Geotechnica - In this study, an analytical model is developed to establish a framework for predicting the coefficient of lateral soil pressure in unsaturated soils. To this end, the disturbed... 相似文献
14.
Ali Moamen Abdelhady A. Abdelmaksoud Ahmed Darwish M. Essa M. A. 《Natural Resources Research》2020,29(2):1259-1281
Natural Resources Research - The Albian/Cenomanian reservoir is one of the two main reservoirs composing the petroleum system in the Komombo Basin. However, these reservoirs have not previously... 相似文献
15.
Ali Almagbile 《地球空间信息科学学报》2019,22(1):23-34
With rapid developments in platforms and sensors technology in terms of digital cameras and video recordings, crowd monitoring has taken a considerable attentions in many disciplines such as psychology, sociology, engineering, and computer vision. This is due to the fact that, monitoring of the crowd is necessary to enhance safety and controllable movements to minimize the risk particularly in highly crowded incidents (e.g. sports). One of the platforms that have been extensively employed in crowd monitoring is unmanned aerial vehicles (UAVs), because UAVs have the capability to acquiring fast, low costs, high-resolution and real-time images over crowd areas. In addition, geo-referenced images can also be provided through integration of on-board positioning sensors (e.g. GPS/IMU) with vision sensors (digital cameras and laser scanner). In this paper, a new testing procedure based on feature from accelerated segment test (FAST) algorithms is introduced to detect the crowd features from UAV images taken from different camera orientations and positions. The proposed test started with converting a circle of 16 pixels surrounding the center pixel into a vector and sorting it in ascending/descending order. A single pixel which takes the ranking number 9 (for FAST-9) or 12 (for FAST-12) was then compared with the center pixel. Accuracy assessment in terms of completeness and correctness was used to assess the performance of the new testing procedure before and after filtering the crowd features. The results show that the proposed algorithms are able to extract crowd features from different UAV images. Overall, the values of Completeness range from 55 to 70 % whereas the range of correctness values was 91 to 94 %. 相似文献
16.
Anjan Kumar Sarkar Somnath Bharadwaj Sk. Saiyad Ali 《Journal of Astrophysics and Astronomy》2017,38(1):14
We use the Fisher matrix formalism to predict the prospects of measuring the redshifted 21-cm power spectrum in different k-bins using observations with the upcoming Ooty Wide Field Array (OWFA) which will operate at 326.5 MHz. This corresponds to neutral hydrogen (HI) at z = 3.35, and a measurement of the 21-cm power spectrum provides a unique method to probe the large-scale structures at this redshift. Our analysis indicates that a 5σ detection of the binned power spectrum is possible in the k range 0.05 ≤ k ≤ 0.3 Mpc?1 with 1000 hours of observation. We find that the signal- to-noise ratio (SNR) peaks in the k range 0.1?0.2 Mpc?1 where a 10σ detection is possible with 2000 hours of observations. Our analysis also indicates that it is not very advantageous to observe beyond 1000 h in a single field-of-view as the SNR increases rather slowly beyond this in many of the small k-bins. The entire analysis reported here assumes that the foregrounds have been completely removed. 相似文献
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18.
Dr. Ali A. Al-Shamlan M. I. Ali El-Sayed Muayyad H. Khaiwka 《International Journal of Earth Sciences》1981,70(3):941-955
Six microfacies are defined on quantitative petrographic data in a carbonate/clastic sequence from the subsurface, oil producing Mauddud Formation of early Middle Cretaceous age. These are, in descending order of importance and abundance: (1) biomicritic wackestone-packstone, (2) argillaceous mudstone, (3) micritic mudstone, (4) glauconitic sandstone, (5)Orhitolina pelsparitic grainstone, and (6) argillaceous dolomite.Sedimentation took place during a marine transgression onto a very shallow, intertidal, restricted marine shelf lagoons. Facies variations appear to be related to depth and energy changes and proximity to areas of clastic deposition. These changes may have been controlled by slight tectonic events in the hinterland and changes in the rate of basin subsidence.
Zusammenfassung Auf der Grundlage quantitativer petrographischer Daten werden sechs Mikrofazies in einer karbonat/klastischen Folge aus der unter der ErdoberflÄche liegenden, ölliefernden Mauddud-Formation der frühen Mittelkreide definiert. In absteigender Reihenfolge der Bedeutung und HÄufigkeit sind dieses: (1) biomikritischer wackestone-packstone, (2) toniger Schlickstein, (3) unkritischer Schlickstein, (4) glaukonitischer Sandstein, (5) Orbitolina-führender pelsparitischer Grainstone und (6) toniger Dolomit.Die Sedimentation erfolgte wÄhrend einer marinen Transgression auf sehr flache, intertidale Lagunen eines begrenzten marinen Schelfs. Die Fazies-Variationen scheinen mit den Wechseln in Wassertiefe und Energie sowie der mit NÄhe von Gebieten mit klastischer Sedimentation zusammenzuhÄngen.Diese Wechsel könnten durch kleinere tektonische Ereignisse im Hinterland und durch VerÄnderungen der Absenkungsrate des Beckens ausgelöst worden sein.
Résumé Des données pétrographiques quantitatives permettent de définir six microfacies dans une série clasto-carbonatée d'âge crétacé inférieur du sous-sol de la région pé trolifère de Mauddud. Ce sont par ordre décroissant d'importance et d'abondance: (1) des wacstones-pacstone biomicritiques; (2) des argilites; (3) des argilites micritiques; (4) des grès glauconitiques; (5) des grainstone pelsparitiques à orbitolines; (6) des dolomies argileuses.La sédimentation se produisit au cours d'une transgression marine dans des lagunes très plates, intercotidales, d'une plate-forme continentale de faible étendue. Les variations de facies semblent Être dues à des changements de profondeur et d'énergie, ainsi qu'à la proximité de régions à sédimentation clastique.Ces changements pourraient résulter de légers mouvements tectoniques dans l'arrière-pays et de variations dans le degré de subsidence du bassin de sédimentation.
- Mauddud, ( ). : 1) ; 2) ; 3) ; 4) ; 5) , 6) . , . , , , . , .相似文献
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20.
Jabbar Moradi Hussein Besharati Hussein Ali Bahrami Mojtaba Karimi 《Environmental Earth Sciences》2013,70(2):799-805
The absence of environmentally sensitive soil management systems can be considered as one of the major risks to sustainability of agricultural soils in Iran. Tillage is the most critical operation in soil management designed to achieve high crop yield, but it can adversely affect the soil fauna in several ways. In the present study, assessment of soil fauna was carried out in Western Iran in 2008 and 2009 in soil subjected to conventional (CT), minimum (MT) and no (NT)-tillage systems and amended with three levels of cattle manure (CM). Earthworm, mite, springtail and nematode populations were measured as indicators of macro, meso and micro fauna groups, respectively. Soil moisture and bulk density were also determined. Generally, low populations of soil fauna were observed consistent with expectations under similar conditions for this region. Earthworm populations were low and had a patchy distribution. Tillage and CM were found to have no effects on soil mites in both years. Soil springtails were reduced by soil tillage, indicating their sensivity to soil disturbance induced by tillage. In 2008, the nematode population was greater with application of 40 ton ha?1 CM applications (113 N.100 g soil?1). Soil tillage-induced disturbance reduced nematode population in 2009 (214 N.100 g soil?1 at CT). Minimum seedbed preparation besides less soil disturbance makes MT a proper tillage system for Zea mays cultivation. Cattle manure application increased Z. mays’ biomass, but according to our results its annual application is not recommended. There were no changes in BD in both years. We conclude that in short-term studies, soil nematode populations are suitable biological indices (under similar soil and climatic conditions) for the ecological comparison of agricultural management systems in Iran. 相似文献