Gradient Map Research Articles

A Robust Descriptor Based on Modality-Independent Neighborhood Information for Optical-SAR Image Matching

Due to the intensity differences and speckle noise, automatic optical-synthetic aperture radar (SAR) image matching is still a challenging task. This letter addresses this problem by proposing a novel descriptor (MaskMIND) with three different modes using modality independent neighborhood information. This descriptor aims to sample and active relative structural information to improve accuracy and precision. In addition, the gradient maps are calculated respectively in pretreatment to eliminate noise. Then the corresponding metric, which takes into account the increasing positional uncertainty with distance, is defined using the sum of squared differences (SSD) accelerated by fast Fourier transform (FFT). Our methods are effective because of its relativeness and abstractness. The experimental results in five optical-SAR image pairs show that our methods have great performance and potentialities. Compared with CFOG, which is the state-of-the-art method, the accuracy of our sMaskMIND-grids is improved by 12% on average.

Atomistic simulation of martensite microstructural evolution during temperature driven [formula omitted] transition in pure titanium

Titanium and its alloys undergo temperature-driven martensitic phase transformation leading to the development of complex microstructures at mesoscale. Optimizing the mechanical properties of these materials requires an understanding of the correlations between the processing parameters and the mechanisms involved in the microstructure formation and evolution. In this work, we study the temperature-induced phase transition from BCC to HCP in pure titanium by atomistic modeling and investigate the influence of local stress conditions on the final martensite morphology. We simulate the transition under different stress conditions and carry a detailed analysis of the microstructural evolution during transition using a deformation gradient map that characterizes the local lattice distortion. The analysis of final martensite morphologies shows how mechanical constraints influence the number of selected variants and the number/type of defects in the final microstructure. We give insight on the origin and structure of different interfaces experimentally observed, such as inter-variant boundaries and antiphase defects. In particular, we show how antiphase defects originate from the two-fold degeneracy shuffling displacement arriving during the transition and how the triple junction formation drives the texture evolution when local stresses prevent a free shape change of the matrix surrounding the growing martensite nuclei.

Geological Terrain Mapping using Geographic Information System (GIS) and Drone Photogrammetry

The research area was conducted within the Bukit Persekutuan, Kuala Lumpur, and it was located at the latitude 3° 8'32.93"N and longitude 101°40'32.80"E. The researcher carried out geological terrain mapping to evaluate the research area in accordance with the geological terrain classification attributes of each thematic map produced, namely, Terrain map, slope gradient map, erosion, and instability map, as well as construction suitability map. The occurrence of landslide events within the research area becomes a major contributing factor to thoroughly conducting an investigation by field mapping and analysing using the Geographic Information System (GIS) technology. The application of Geographic Information System (GIS) and drone photogrammetry images play an essential role to analyze and process the data, thus, generate the thematic maps. The research area indicates that about 79.11% of the overall area was not appreciable with erosion, 8.58% contribute to the erosion, 11.00% of recent general instability, and 2.97% represent a landslide event. The suitability for development mapping illustrated Class I (23.40), Class II (36.37%), Class III (26.39%), and Class IV (15.50%) where it can be referred to the construction suitability classification system, the suitability for development was high in class I, moderate in class II, low in class III and not suitable in class IV.

COMPACT ORBITS OF PARABOLIC SUBGROUPS

AbstractWe study the action of a real reductive group G on a real submanifold X of a Kähler manifold Z. We suppose that the action of a compact connected Lie group U with Lie algebra $\mathfrak {u}$ extends holomorphically to an action of the complexified group $U^{\mathbb {C}}$ and that the U-action on Z is Hamiltonian. If $G\subset U^{\mathbb {C}}$ is compatible, there exists a gradient map $\mu _{\mathfrak p}:X \longrightarrow \mathfrak p$ where $\mathfrak g=\mathfrak k \oplus \mathfrak p$ is a Cartan decomposition of $\mathfrak g$ . In this paper, we describe compact orbits of parabolic subgroups of G in terms of the gradient map $\mu _{\mathfrak p}$ .

BPS black hole entropy and attractors in very special geometry. Cubic forms, gradient maps and their inversion

We consider Bekenstein-Hawking entropy and attractors in extremal BPS black holes of mathcal{N} = 2, D = 4 ungauged supergravity obtained as reduction of minimal, matter-coupled D = 5 supergravity. They are generally expressed in terms of solutions to an inhomogeneous system of coupled quadratic equations, named BPS system, depending on the cubic prepotential as well as on the electric-magnetic fluxes in the extremal black hole background. Focussing on homogeneous non-symmetric scalar manifolds (whose classification is known in terms of L(q, P, Ṗ) models), under certain assumptions on the Clifford matrices pertaining to the related cubic prepotential, we formulate and prove an invertibility condition for the gradient map of the corresponding cubic form (to have a birational inverse map which is given by homogeneous polynomials of degree four), and therefore for the solutions to the BPS system to be explicitly determined, in turn providing novel, explicit expressions for the BPS black hole entropy and the related attractors as solution of the BPS attractor equations. After a general treatment, we present a number of explicit examples with Ṗ = 0, such as L(q, P), 1 ⩽ q ⩽ 3 and P ⩾ 1, or L(q, 1), 4 ⩽ q ⩽ 9, and one model with Ṗ = 1, namely L(4, 1, 1). We also briefly comment on Kleinian signatures and split algebras. In particular, we provide, for the first time, the explicit form of the BPS black hole entropy and of the related BPS attractors for the infinite class of L(1, P) P ⩾ 2 non-symmetric models of mathcal{N} = 2, D = 4 supergravity.

DSPI Filtering Evaluation Method Based on Sobel Operator and Image Entropy

Evaluating the filtering process of the digital speckle pattern interferometry (DSPI) of a single image by the traditional methods can result in under- or over-filtering. To solve this problem, this paper proposes an image-filtering evaluation method based on the Sobel operator and image entropy. First, the Sobel operator is introduced to convolute a filtered image to obtain a gradient image of a DSPI. Then, by analyzing the gradient image, image entropy is calculated according to the characteristics of the gradient map. Finally, the proposed method is verified by experiments. The experimental results show that the proposed method can quantitatively evaluate the filtering process of the DSPI.

Connected components of the space of proper gradient vector fields

We show that there exist two proper gradient vector fields on mathbb {R}^n which are homotopic in the category of proper maps but not homotopic in the category of proper gradient maps.

A hybrid approach for water body identification from satellite images using NDWI mapping and histogram of gradients

A hybrid approach for water body identification from satellite images using NDWI mapping and histogram of gradients

Retraction Note: Analysis on the legal regulation of mountainous plant protection and agricultural waste resources based on the concept of circular economy

The sustainable development of modern agriculture must not only support the sustainable development of the industry itself, but also must realize the recycling of industrial accessories (such as agricultural waste) and the exploitation of potential. As an important part of the development of the concept of circular economy, an important part of circular agricultural technology is the conversion and utilization of waste sources. This is a new type of agricultural technology aimed at pursuing higher efficiency, reducing pollution, and increasing more employment goals. It can be seen that the initiation and implementation of agricultural waste recycling technology is the meaning of sustainable agricultural development. However, with the development of current technology, problems such as the lack of the concept of circular economy and the understanding of the main body of agricultural waste recycling, the incomplete service system, and the lagging of supporting policies and measures have emerged. Consistent with this, this paper uses GrcGIS and other methods to draw a gradient map to ensure that the protection of mountain plants in the mountainous area of City A is implemented at the district/county and city level. This confirms that the diversity of mountain plant protection is consistent at the district/county and city levels, that is, areas with the most species diversity contain more endangered species. Finally, the article expounds the status quo of China’s legal regulation of recycling and the consequences of model analysis, and puts forward the countermeasures and suggestions on China’s legal regulation of recycling, such as legislation, management system, statistical information collection and release system resources, law enforcement procedures, and initial allocation of rights.

New Results on Small and Dim Infrared Target Detection

Real-time small infrared (IR) target detection is critical to the performance of the situational awareness system in high-altitude aircraft. However, current IR target detection systems are generally hardware-unfriendly and have difficulty in achieving a robust performance in datasets with clouds occupying a large proportion of the image background. In this paper, we present new results by using an efficient method that extracts the candidate targets in the pre-processing stage and fuses the local scale, blob-based contrast map and gradient map in the detection stage. We also developed mid-wave infrared (MWIR) and long-wave infrared (LWIR) cameras for data collection experiments and algorithm evaluations. Experimental results using both publicly available datasets and image sequences acquired by our cameras clearly demonstrated that the proposed method achieves high detection accuracy with the mean AUC being at least 22.3% higher than comparable methods, and the computational cost beating the other methods by a large margin.

Histograms of oriented mosaic gradients for snapshot spectral image description

This paper presents a feature descriptor using Histogram of Oriented Mosaic Gradient (HOMG) that extracts spatial-spectral features directly from mosaic spectral images. Spectral imaging utilizes unique spectral signatures to distinguish objects of interest in the scene more discriminatively. Snapshot spectral cameras equipped with spectral filter arrays (SFAs) capture spectral videos in real time, making it possible to detect/track fast moving targets based on spectral imaging. How to effectively extract the spatial-spectral feature directly from the mosaic spectral images acquired by snapshot spectral cameras is a core issue for detection/tracking. So far, there is a lack of comprehensive and in-depth research on this issue. To this end, this paper proposed a new spatial-spectral feature extractor for mosaic spectral images. The proposed scheme finds two forms of SFA neighborhood (SFAN) to construct a feature extractor suitable for any SFA structure. Exploiting the spatial-spectral correlation in two SFANs, we design six mosaic spatial-spectral gradient operators to compute spatial-spectral gradient maps (SGMs). HOMG descriptors are constructed using the magnitude and orientation of SGMs. The effectiveness and generalizability of the proposed method have been verified with object tracking experiments. Compared to the state-of-the-art feature descriptors, HOMG ranked first on two datasets captured with snapshot spectral camera with different SFAs, achieving a gain of 3.9% and 5.9% in average success rate over the second-ranked feature.

Geothermal Reservoir Identification in Way Ratai Area Based on Gravity Data Analysis

Gravity research in the Way Ratai geothermal prospect area was conducted to determine geothermal reservoirs, heat sources, and the structure of the geothermal reservoir. The research carried out includes 3D inversion modeling of gravity data. The Bouguer anomaly in the study area has 50 mGal to 120 mGal with low anomalies located in the southeast (Ketang and Kelagian), Northeast (Gedong Air, Sungai Langka, Gunung Betung) areas, and in the Pesawaran mountain area. The high anomaly is in Merawan – Hanuberak – Padang Cermin, Sumbersari and Kaliawi. The horizontal gravity gradient map analysis shows a pattern of fault structure trending northwest-southeast and southwest-northeast, according to the main fault structure in the area. 3D inversion modeling obtains a density distribution between 1.8 g/cc to 3g/cc with a low-density distribution in the south, Mount Pesawaran/Ratai, Gunung Betung, and Sidoharum. The location of the manifestation is 9 km southeast of the Mount Ratai/Pesawaran summit. The existence of geothermal reservoirs is estimated to be in the Lubuk Badak and Miwung Hills areas which are located between the peaks of Mount Ratai/Pesawaran and geothermal manifestations. This is supported by the low-density distribution in the area and the resistivity map from audio-magnetotelluric data.

Resolving Chemical Gradients Around Seagrass Roots—A Review of Available Methods

Steep geochemical gradients surround roots and rhizomes of seagrass and protect the plants against the harsh conditions in anoxic sediment, while enabling nutrient uptake. Imbalance of these gradients, due to e.g., low plant performance and/or changing sediment biogeochemical conditions, can lead to plant stress and large-scale seagrass meadow die-off. Therefore, measuring and mapping the dynamic gradients around seagrass roots and rhizomes is needed to better understand plant responses to human impact and environmental changes. Historically, electrochemical microsensors enabled the first measurements of important chemical species like O2, pH or H2S with high sensitivity and spatial resolution giving important insights to the seagrass rhizosphere microenvironment; however, such measurements only provide information in one dimension at a time. In recent years, the use of reversible optical sensors (in the form of planar optodes or nanoparticles) and accumulative gel sampling methods like Diffusive Gradients in Thin films (DGT) have extended the array of analytes and allowed 2-D mapping of chemical gradients in the seagrass rhizosphere. Here, we review and discuss such microscale methods from a practical angle, discuss their application in seagrass research, and point toward novel experimental approaches to study the (bio)geochemistry around seagrass roots and rhizomes using a combination of available techniques, both in the lab andin situ.

A Splitting Result for Real Submanifolds of a Kähler Manifold

Let (Z,omega ) be a connected Kähler manifold with an holomorphic action of the complex reductive Lie group U^mathbb {C}, where U is a compact connected Lie group acting in a hamiltonian fashion. Let G be a closed compatible Lie group of U^mathbb {C} and let M be a G-invariant connected submanifold of Z. Let xin M. If G is a real form of U^mathbb {C}, we investigate conditions such that Gcdot x compact implies U^mathbb {C}cdot x is compact as well. The vice-versa is also investigated. We also characterize G-invariant real submanifolds such that the norm-square of the gradient map is constant. As an application, we prove a splitting result for real connected submanifolds of (Z,omega ) generalizing a result proved in Gori and Podestà (Ann Global Anal Geom 26: 315–318, 2004), see also Bedulli and Gori (Results Math 47: 194–198, 2005), Biliotti (Bull Belg Math Soc Simon Stevin 16: 107–116 2009).

Road Detection Based on Edge Feature with GAC Model in Aerial Image

Road detection from aerial images still is a challenging task since it is heavily influenced by spectral reflectance, shadows and occlusions. In order to increase the road detection accuracy, a proposed method for road detection by GAC model with edge feature extraction and segmentation is studied in this paper. First, edge feature can be extracted using the proposed gradient magnitude with Canny operator. Then, a reconstructed gradient map is applied in watershed transformation method, which is segmented for the next initial contour. Last, with the combination of edge feature and initial contour, the boundary stopping function is applied in the GAC model. The road boundary result can be accomplished finally. Experimental results show, by comparing with other methods in [Formula: see text]-measure system, that the proposed method can achieve satisfying results.

Reconciling the Infrared and Microwave Observations of the Lunar South Pole: A Study on Subsurface Temperature and Regolith Density

AbstractThe Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter and the Microwave Radiometer (MRM) onboard Chang'e‐2 (CE‐2) orbiter performed nearly coincident measurements of the lunar south polar region in 2010–2011. In this study, we reconcile infrared data from Diviner and microwave data from MRM to reveal thermal behavior of lunar regolith at very low temperatures. Assuming a uniform density structure and dielectric properties across the polar region, we retrieve a relative apparent thermal‐gradient map based on radiative transfer model. The result shows apparent thermal gradients in the permanently shadowed regions (PSRs) are much larger than that in non‐PSRs, which implies a systematic difference in thermal conductivity and/or density of lunar regolith in PSRs. We also model surface temperature and microwave brightness temperature over time in PSR and non‐PSR locations. The modeling results at these representative locations and the thermal gradient map confirm that the regolith in the PSRs is consistent with a much lower thermal conductivity and higher porosity than non‐PSRs.

Gradient Guided Pyramidal Convolution Residual Network with Interactive Connections for Pan-sharpening

ABSTRACT Convolutional neural networks (CNNs) have played a predominant role in the field of remote sensing over the last few years. As a significant branch of remote sensing image processing, pan-sharpening technique is to produce a high-resolution multi-spectral (HRMS) image based on a low-resolution multi-spectral (LRMS) image and a high-resolution (HR) panchromatic (PAN) image. Benefiting from the inherently powerful representation ability, deep-learning-based methods have also achieved promising and favourable performance in pan-sharpening community. However, these methods don’t take advantage of the gradient characteristic which contains abundant structure information to guide the pan-sharpening process, failing to achieve the desired spatial preservation. In this paper, we propose a gradient-guided pyramidal convolution residual network with interactive connections (GGPCRN) to relieve the above issue. Specifically, besides the indispensable reconstruction branch, an auxiliary gradient branch providing additional structure information is built to guide the recovery process. Moreover, we introduce pyramidal convolution containing a series of filters with varying depth and size into our network to capture different scales of details for better performance. To further enhance the guidance of gradient maps, two measures are taken. On the one hand, interactive connections are proposed to transfer the mutual effect between the reconstruction branch and gradient branch. On the other hand, we incorporate a mild gradient loss to force a second-order restraint on the pan-sharpened images, making the network concentrate more on structure preservation. Both reduced-resolution and full-resolution experiments suggest that our GGPCRN performs favourably against other methods in terms of quantitative evaluations and visual improvements.

B-AB01-03 HIGH-RESOLUTION REAL-TIME LEFT-VENTRICULAR ENDOCARDIAL ACTIVATION-REPOLARIZATION MAPPING IN AN IN-VIVO CANINE MODEL OF DRUG-INDUCED LONG-QT 1 SYNDROME AND TORSADES DE POINTES

Congenital loss of function or drug-induced inhibition of IKs causes repolarization lability, predisposing to QT prolongation (LQT1) and sympathetically-evoked torsades de pointes (TdP). High-resolution in-vivo mapping of endocardial activation-repolarization times (AT, RT), gradients and focal excitation conspiring to TdP in LQT1 is lacking. To study arrhythmogenic mechanisms of TdP in a canine model of drug-induced LQT1 using real-time and high-resolution electroanatomical mapping. IKs inhibition (HMR1556 0.025-0.05 mg/kg/min) was applied in three fentanyl/etomidate-anesthetized dogs; anesthesia to maintain near-normal autonomic responsiveness. The AcQMap3D noncontact imaging and mapping catheter (Acutus Medical, US) was positioned in the LV. Isoproterenol (1.25-2.5 mcg/kg) induced TdP. AT, RT (Wyatt), RTmax-min (ΔRT), local RT dispersion (per 5.5 mm) and TdP initiation/propagation were studied. IKs block prolonged QTc by 40% (386±22 ms) and mean RT by 44% (309±20 ms), as recorded with the AcQMap3D catheter (AT/RT errors 2.9±4.0/5.4±6.7 ms; cross-correlation 1.0±0.1; time difference 0.8±1.8 ms). ΔRT increased by 23% (85±7 ms) and max local RT dispersion by 19% (80±9 ms). Isoproterenol induced regional RT shortening (base>apex) and beat-to-beat instability, increasing ΔRT significantly by 122% (189±62 ms) and local RT dispersion by 91% (153±51 ms; Figure). Focal triggers of TdP emerged from regions bordering high RT dispersion, driving reentrant excitation. High-resolution mapping in an in-vivo LQT1/TdP model uniquely identifies spatiotemporal RT instabilities, focal excitation and TdP.

Determination of Biodegradation Zone in Central Sumatra Basin

It is commonly known that heavy oil is mostly formed through biodegradation process within reservoir or on the surface both by aerobic and/or anaerobic bacteria that can live under specfi c temperature level(s). In order to investigate heavy oil occurences in Central Sumatra Basin, eff orts have been spent to determine the depths that represent the maximum temperature. By integrating the maximum viable temperature of typical bacteria and temperature gradient data, the depth of heavy oil zone is determined. The work is a combination of establishment of geothermal gradient map and laboratory analysis on fi eld sampled oil for determining types and temperature characteristics of microorganism living in the samples. Heavy oil sampling is made on seepages in areas nearby Minas fi eld. Subsequent laboratory analysis reveals Burkholderia multivorans ATCC BAA-247 as the predominant bacteria having maximum viabl temperature of 60° C. Based on the established geothermal gradient map, this maximum temperature correspond to average depth of 1818 ft (555.5 m). This average depth is used as the lower depth for the biodegradation zone over which investigation over presence of heavy oil bearing reservoirs/traps is made.

Comparison of Terrestrial Gravity and EGM 2008 Data on Extracted Lineaments: A Case Study of the Adamawa Massif, North Cameroon

A structural study on the Adamawa Massif highlights the major structures (faults) of the shear zone as well as the igneous intrusion near Mayo Baleo. Through this study, a comparison on the use of gravity data from the EGM 2008 and terrestrial models was carried out on the basis of gridded gradient data obtained by applying the MAGMAP filtering algorithm on the Oasis Montaj software system. Using the gradients has an advantage in that they contain much information especially on geological structures. The resulting maxima have strong density contrasts, enabling them to be used as tools in explaining geological contacts. Gravimetric lineaments marked by the geometry of the peaks (elongated shape) and the igneous intrusion corresponding to the circular peak were detected on the horizontal gradient maps. Reconciliation with the geology, the slope map and satellite images justifies the presence of the Djohong-Ngaoundal-Dir-Tibati, Tibati-Banyo and Tignere-Banyo lineaments which indicate the underlying Foumban (extension), Tibati and Tchollire-Banyo faults respectively, comprising the shear system residing in the massif underlain by a gneiss-migmatite bedrock. The limitation on the use of gravity data from the EGM 2008 model is manifested through the Djohong lineament correlating with the large mylonitized feature trending NE-SW, defined as a steep relief (27° to 60°), separating the Mbere basin from the upper unit with about 358 m in height difference. This terrain is a small area of relief with morphological units adapted as in the case of the mountainous areas of the West to the use of gravity data from the EGM2008. The other lineaments that are part of the shear zone fault system are not elucidated because they correspond to deep mega structures that the EGM 2008 model resolution cannot attain at depth. The use of this model is suitable for studies of superficial structures which are associated with huge formations such as the volcanic dome of Mayo Baleo, an intrusion of young trachytes with steep slopes (27° to 60°) at an altitude of 2419 m.