Slant Direction Research Articles

Perception of 3D slant from textures with and without aligned spectral components.

The image of a textured surface provides multiple potential cues that could be used to perceive its 3D structure. When a surface texture has oriented structure, perspective convergence of the oriented components provides a texture cue, in addition to texture scaling and compression. Some findings suggest that oriented spectral components aligned with the direction of slant are important for 3D perception from texture, but this has only been demonstrated in restricted situations. In this study, we tested the contribution of oriented spectral components for planar surface patches with varied slant (0°-80°) and field of view (16° and 6°). Observers viewed simulated textured surfaces and estimated slant to the perceived surfaces. The simulated textures were octotropic plaids with a full range of orientations, or with either the aligned or perpendicular plaid components removed. We measured perceptual bias in monocular conditions and also the relative weighting of texture and stereo information in binocular conditions. We found that the presence of aligned spectral components did produce some improvement in slant estimates, but the effects were small and only observed in some conditions. There were no detectable differences in texture cue weights. Our results demonstrate that aligned spectral components contribute to perception of slant from texture, but suggest that the contribution is limited when other texture cues are available and informative. Our findings are consistent with the notion that the visual system utilizes multiple sources of texture information for 3D perception.

Retrieval of Three-Dimensional Surface Deformation Using an Improved Differential SAR Tomography System

Conventional differential synthetic aperture radar tomography (D-TomoSAR) can only capture the scatterers’ one-dimensional (1-D) deformation information along the line of sight (LOS) of the synthetic aperture radar (SAR), which means that it cannot retrieve the three-dimensional (3-D) movements of the ground surface. To retrieve the 3-D deformation displacements, several methods have been proposed; the performance is limited due to the insufficient sensitivity for retrieving the North-South motion component. In this paper, an improved D-TomoSAR model is established by introducing the scatterers’ 3-D deformation parameters in slant range, azimuth, and elevation directions into the traditional D-TomoSAR model. The improved D-TomoSAR can be regarded as a multi-component two-dimensional (2-D) polynomial phase signal (PPS). Then, an effective algorithm is proposed to retrieve the 3-D deformation parameters of the ground surface by the 2-D product high-order ambiguity function (PHAF) with the relax (RELAX) algorithm. The estimation performance is investigated and compared with the traditional algorithm. Simulations and experimental results with semi-real data verify the effectiveness of the proposed signal model and algorithm.

General characteristics of morphometric and morphoscopic signs of liver rupture with different localizations

The aim of this study was to compare the morphoscopic and morphometric features of local and remote liver ruptures under various external influences. It was found that the local main ruptures were formed in the case of impact trauma more often in the right side of the liver on its diaphragmatic surface, in the anterior third of the organ. They were linear and located in the longitudinal direction. The size of the ruptures increased as the impact force increased. Local additional ruptures were associated with impact and compression trauma and were located only on the diaphragmatic surface of the liver, more often in the right half, in the middle third of the organ. These ruptures were linear, co-directional and small in size under various external influences. Central ruptures were formed by impact and compression trauma, were located more often in the middle third of the right side of the liver and were slit-shaped with a longitudinal direction. The size of central ruptures was associated with falls on the stomach and compression trauma. Peripheral ruptures were formed in the case of impact and compression trauma, were located more often in the right half of the liver on its diaphragmatic surface, mainly in the middle third of the organ and were linear with a slanting direction. The relative constancy of the average sizes of peripheral ruptures was noted. Anti-shock ruptures were observed resulting from shock trauma and were located more often in the right side of the liver, on its visceral surface, in the rear third of the organ. They were linear and curvilinear, and longitudinally and obliquely oriented. Ruptures were relatively constant in size with different types of impact.

Multilayer formation via spinodal decomposition in TiO2-VO2 epitaxial films on sapphire substrates

We present multilayer formation via spinodal decomposition in rutile TiO2-VO2 (TVO) epitaxial films on sapphire substrates. (001)- and (101)-oriented TVO solid-solution films are grown epitaxially on TiO2/Al2O3 using a pulsed laser deposition technique and annealed inside the spinodal region. X-ray diffraction measurements and scanning transmission electron microscopy (STEM) observations show that the films are phase-separated along the [001] direction and lamellar structures are formed in a parallel or slanted direction to the sapphire substrates depending on the film orientation. The results indicate the multilayer formation via spinodal decomposition in the TVO films. STEM investigations also reveal a relatively high Ti concentration in the decomposed phases, reflecting the influence of lattice deformation on the phase decomposition in the films. Our work shows that spinodal decomposition is a promising approach for the formation of a multilayer structure in TVO films and helps deepen understanding the spinodal decomposition in TVO system.

Large-area tsunami signatures in ionosphere observed by GPS TEC after the 2011 Tohoku earthquake

The internal gravity waves (IGWs) produced by a tsunami can travel into the ionosphere and trigger traveling ionospheric disturbances (TIDs). In this study, we report ionospheric measurements related to the huge transpacific tsunami induced by the 2011 Tohoku earthquake. The total electron content (TEC) extracted from far-field GPS network in the US is employed to detect the TIDs induced by the tsunami. We observed the large-area tsunami-driven TIDs in TEC, which have similar propagation characteristics regarding waveform, arrival time, period, horizontal velocity and direction compared to the tsunami measurements at sea-level. Furthermore, the large-area tsunami-driven TIDs are observed in the ionosphere over not only the ocean but also land, illustrating effectively that the IGWs propagate into the ionosphere along the slant direction. In addition, the raypaths of GPS satellites along the propagation direction of IGWs can observe more significant signatures. These observed results provide a more comprehensive propagation characteristic for tsunami-driven TIDs, which can help to better know the tsunami-ionosphere coupling process.

Spoof surface plasmon polaritons excitation and wavefront control by Pancharatnam–Berry phase manipulating metasurface

Realizing fine control of surface plasmon polaritons (SPPs) and spoof surface plasmon polaritons (SSPPs) is highly desired in many integrated photonic and microwave applications, but the flexibility to control the wavefront of SPPs and SSPPs still need addressing. In this paper, a Pancharatnam–Berry (PB) phase manipulating metasurface (PMM) was designed to achieve SSPPs excitation and wavefront control. Under circular polarization (CP) incidence, simply by designing the rotation angle of the unit cells the reflection phase spatial distribution can be manipulated. By means of different phase profiles on the 2D unit cells array, the SSPPs can be excited with various wavefront shapes, without the need of special excitation structure pattern. Meanwhile, a plasmonic metal is also designed to support SSPPs with both TE and TM polarizations, which can efficiently guide out the energies from the input CP waves. As a proof of concept, a PB PMM composed of N-shape metallic structure was designed. Through designing the rotation of the unit cells, two typical phase profiles were designed to excite SSPPs in arbitrary slant direction or focusing. This scheme could be used to achieve SSPPs excitation with many other wavefront shapes, and would also enable promising applications in other spectra.

Behavioral flexibility in learning to sit.

What do infants learn when they learn to sit upright? We tested behavioral flexibility in learning to sit-the ability to adapt posture to changes in the environment-in 6- to 9-month-old infants sitting on forward and backward slopes. Infants began with slant at 0°; then slant increased in 2° increments until infants lost balance. Infants kept balance on impressively steep slopes, especially in the forward direction, despite the unexpected movements of the apparatus. Between slant adjustments while the slope was stationary, infants adapted posture to the direction and degree of slant by leaning backward on forward slopes and forward on backward slopes. Postural adaptations were nearly optimal for backward slopes. Sitting experience predicted greater postural adaptations and increased ability to keep balance on steeper changes of slant, but only for forward slopes. We suggest that behavioral flexibility is integral to learning to sit and increases with sitting experience.

Lithospheric low-velocity zones associated with a magmatic segment of the Tanzanian Rift, East Africa

Rifting in a cratonic lithosphere is strongly controlled by several interacting processes including crust/mantle rheology, magmatism, inherited structure and stress regime. In order to better understand how these physical parameters interact, a 2 yr long seismological experiment has been carried out in the North Tanzanian Divergence (NTD), at the southern tip of the eastern magmatic branch of the East African rift, where the southward-propagating continental rift is at its earliest stage. We analyse teleseismic data from 38 broad-band stations ca. 25 km spaced and present here results from their receiver function (RF) analysis. The crustal thickness and Vp/Vs ratio are retrieved over a ca. 200 × 200 km2 area encompassing the South Kenya magmatic rift, the NTD and the Ngorongoro-Kilimanjaro transverse volcanic chain. Cratonic nature of the lithosphere is clearly evinced through thick (up to ca. 40 km) homogeneous crust beneath the rift shoulders. Where rifting is present, Moho rises up to 27 km depth and the crust is strongly layered with clear velocity contrasts in the RF signal. The Vp/Vs ratio reaches its highest values (ca. 1.9) beneath volcanic edifices location and thinner crust, advocating for melting within the crust. We also clearly identify two major low-velocity zones (LVZs) within the NTD, one in the lower crust and the second in the upper part of the mantle. The first one starts at 15–18 km depth and correlates well with recent tomographic models. This LVZ does not always coexist with high Vp/Vs ratio, pleading for a supplementary source of velocity decrease, such as temperature or composition. At a greater depth of ca. 60 km, a mid-lithospheric discontinuity roughly mimics the step-like and symmetrically outward-dipping geometry of the Moho but with a more slanting direction (NE–SW) compared to the NS rift. By comparison with synthetic RF, we estimate the associated velocity reduction to be 8–9 per cent. We relate this interface to melt ponding, possibly favouring here deformation process such as grain-boundary sliding (EAGBS) due to lithospheric strain. Its geometry might have been controlled by inherited lithospheric fabrics and heterogeneous upper mantle structure. We evidence that crustal and mantle magmatic processes represent first order mechanisms to ease and locate the deformation during the first stage of a cratonic lithospheric breakup.

Detection and accuracy of landslide movement by InSAR analysis using PALSAR-2 data

Interferometric synthetic aperture radar (InSAR) analysis is a radar technique for generating large-area maps of ground deformation using differences in the phase of microwaves returning to a satellite. In recent years, high-resolution SAR sensors have been developed that enable small-scale slope deformation to be detected, such as the partial block movement of a landslide. The L-band SAR (PALSAR-2) is mounted on Advanced Land Observing Satellite-2 (ALOS-2), which was launched on 24 Mar. 2014. Its main improvements compared with ALOS are enhanced resolution of as high as 3 m with a high-frequency recurrence period (14 days). Owing to its high resolution and the use of the L-band, PALSAR-2 can obtain reflective data passing through a tree canopy surface, unlike the other synthetic aperture radars. Therefore, the coherence of InSAR in mountainous forest areas is less likely to decrease, making it advantageous for the extraction of slope movement. In this study, to verify the accuracy of InSAR analysis using PALSAR-2 data, we compared the results of InSAR analysis and the measurement of the displacement in a landslide by global navigation satellite system (GNSS) observation. It was found that the average difference between the displacements obtained by InSAR analysis and the field measurements by GNSS was only 15.1 mm in the slant range direction, indicating the high accuracy of InSAR analysis. Many of the areas detected by InSAR analysis corresponded to the locations of surface changes due to landslide activity. Additionally, in the areas detected by InSAR analysis using multiple datasets, the ground changes due to landslide movement were confirmed by site investigation.

Presidential Debates in the Age of Partisan Media: A Field Experiment

To investigate media effects in political campaigns, we administered a field experiment around the first general election presidential debate of 2016. In this three-wave study, subjects were randomly incentivized to watch the debate and post-debate television coverage on Fox News or MSNBC. We find that post-debate coverage has strong effects on performance evaluations, with subjects' perceptions moving in the direction of the partisan slant of the channel they were assigned to watch on. Though these effects evolve over time, with subjects coming to express beliefs more in line with the media consensus, they do not disappear altogether. Moderate partisans were still affected by the post-debate coverage a week later. The effects we observe are limited to debate evaluations; at no point do we observe partisan media affecting vote choice. Our results offer evidence that media effects can persist over time, but are confined to candidate evaluations.

Decomposing DInSAR Time-Series into 3-D in Combination with GPS in the Case of Low Strain Rates: An Application to the Hyblean Plateau, Sicily, Italy

Differential Interferometric SAR (DInSAR) time-series techniques can be used to derive surface displacement rates with accuracies of 1 mm/year, by measuring the one-dimensional distance change between a satellite and the surface over time. However, the slanted direction of the measurements complicates interpretation of the signal, especially in regions that are subject to multiple deformation processes. The Simultaneous and Integrated Strain Tensor Estimation from Geodetic and Satellite Deformation Measurements (SISTEM) algorithm enables decomposition into a three-dimensional velocity field through joint inversion with GNSS measurements, but has never been applied to interseismic deformation where strain rates are low. Here, we apply SISTEM for the first time to detect tectonic deformation on the Hyblean Foreland Plateau in South-East Sicily. In order to increase the signal-to-noise ratio of the DInSAR data beforehand, we reduce atmospheric InSAR noise using a weather model and combine it with a multi-directional spatial filtering technique. The resultant three-dimensional velocity field allows identification of anthropogenic, as well as tectonic deformation, with sub-centimeter accuracies in areas of sufficient GPS coverage. Our enhanced method allows for a more detailed view of ongoing deformation processes as compared to the single use of either GNSS or DInSAR only and thus is suited to improve assessments of regional seismic hazard.

Disturbance of the inclined inserting-type sand fence to wind–sand flow fields and its sand control characteristics

Abstract The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind–sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.

CO-REGISTRATION OF TERRESTRIAL AND UAV-BASED IMAGES – EXPERIMENTAL RESULTS

Abstract. For many applications within urban environments the combined use of images taken from the ground and from unmanned aerial platforms seems interesting: while from the airborne perspective the upper parts of objects including roofs can be observed, the ground images can complement the data from lateral views to retrieve a complete visualisation or 3D reconstruction of interesting areas. The automatic co-registration of air- and ground-based images is still a challenge and cannot be considered solved. The main obstacle is originating from the fact that objects are photographed from quite different angles, and hence state-of-the-art tie point measurement approaches cannot cope with the induced perspective transformation. One first important step towards a solution is to use airborne images taken under slant directions. Those oblique views not only help to connect vertical images and horizontal views but also provide image information from 3D-structures not visible from the other two directions. According to our experience, however, still a good planning and many images taken under different viewing angles are needed to support an automatic matching across all images and complete bundle block adjustment. Nevertheless, the entire process is still quite sensible – the removal of a single image might lead to a completely different or wrong solution, or separation of image blocks. In this paper we analyse the impact different parameters and strategies have on the solution. Those are a) the used tie point matcher, b) the used software for bundle adjustment. Using the data provided in the context of the ISPRS benchmark on multi-platform photogrammetry, we systematically address the mentioned influences. Concerning the tie-point matching we test the standard SIFT point extractor and descriptor, but also the SURF and ASIFT-approaches, the ORB technique, as well as (A)KAZE, which are based on a nonlinear scale space. In terms of pre-processing we analyse the Wallis-filter. Results show that in more challenging situations, in this case for data captured from different platforms at different days most approaches do not perform well. Wallis-filtering emerged to be most helpful especially for the SIFT approach. The commercial software pix4dmapper succeeds in overall bundle adjustment only for some configurations, and especially not for the entire image block provided.

CO-REGISTRATION OF TERRESTRIAL AND UAV-BASED IMAGES – EXPERIMENTAL RESULTS

For many applications within urban environments the combined use of images taken from the ground and from unmanned aerial platforms seems interesting: while from the airborne perspective the upper parts of objects including roofs can be observed, the ground images can complement the data from lateral views to retrieve a complete visualisation or 3D reconstruction of interesting areas. The automatic co-registration of air- and ground-based images is still a challenge and cannot be considered solved. The main obstacle is originating from the fact that objects are photographed from quite different angles, and hence state-of-the-art tie point measurement approaches cannot cope with the induced perspective transformation. One first important step towards a solution is to use airborne images taken under slant directions. Those oblique views not only help to connect vertical images and horizontal views but also provide image information from 3D-structures not visible from the other two directions. According to our experience, however, still a good planning and many images taken under different viewing angles are needed to support an automatic matching across all images and complete bundle block adjustment. Nevertheless, the entire process is still quite sensible – the removal of a single image might lead to a completely different or wrong solution, or separation of image blocks. <br><br> In this paper we analyse the impact different parameters and strategies have on the solution. Those are a) the used tie point matcher, b) the used software for bundle adjustment. Using the data provided in the context of the ISPRS benchmark on multi-platform photogrammetry, we systematically address the mentioned influences. Concerning the tie-point matching we test the standard SIFT point extractor and descriptor, but also the SURF and ASIFT-approaches, the ORB technique, as well as (A)KAZE, which are based on a nonlinear scale space. In terms of pre-processing we analyse the Wallis-filter. Results show that in more challenging situations, in this case for data captured from different platforms at different days most approaches do not perform well. Wallis-filtering emerged to be most helpful especially for the SIFT approach. The commercial software pix4dmapper succeeds in overall bundle adjustment only for some configurations, and especially not for the entire image block provided.

Influences of extinction coefficient profile on the estimation of Slant Visual Range

Abstract Slant Visual Range (SVR) is defined as the distance at which the contrast of a given object with respect to its background is just equal to the contrast threshold of an observer in slant direction. In this study, estimation methods and errors of SVR are explored in lidar-free circumstances where Extinction Coefficient Profile (ECP), vertical distribution of Single Scattering Albedo (SSA) and asymmetry parameter (ASY) cannot be acquired. Statistical characteristics of aerosol optical properties in the Taklimakan Basin for sand-dust weather are derived from the CALIPSO daytime aerosol product from 2011 to 2014. SSA and ASY are approximated as 0.92 and 0.7 because aerosol types are mainly dust and polluted dust throughout layers. Besides, ECP can be categorized into exponential, Gaussian and other patterns. Based on whether the determination of real ECP into one of the three patterns is feasible, two SVR estimation methods are introduced and termed the accurate estimation method (AEM) and the blind estimation method (BEM), both methods are performed using SBDART radiative transfer model. For the AEM, analysis of estimated SVR and real SVR reveals a minimum linear correlation coefficient of 0.98 and a maximum root mean square error of 0.07, and the hit rate (R) of SVR estimation increases from 86% to nearly 100% when the maximum allowable relative error (MARE) increases from 10% to 25%. Validation of the BEM shows that R varies from 78% to 100% for MARE of 25% and falls drastically with the decrease of MARE, with the highest R value in spring and summer for the Gaussian pattern and the lowest values in fall and winter for exponential and other patterns. This study is among the first to explore the feasibility and methodology of deriving SVR in lidar-free circumstances.

Determination of optimum viewing angles for the angular normalization of land surface temperature over vegetated surface.

Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST) retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF) is first extended to the thermal infrared (TIR) domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir) from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors.

Brightness masking is modulated by disparity structure

The luminance contrast at the borders of a surface strongly influences surface’s apparent brightness, as demonstrated by a number of classic visual illusions. Such phenomena are compatible with a propagation mechanism believed to spread contrast information from borders to the interior. This process is disrupted by masking, where the perceived brightness of a target is reduced by the brief presentation of a mask (Paradiso & Nakayama, 1991), but the exact visual stage that this happens remains unclear. In the present study, we examined whether brightness masking occurs at a monocular-, or a binocular-level of the visual hierarchy. We used backward masking, whereby a briefly presented target stimulus is disrupted by a mask coming soon afterwards, to show that brightness masking is affected by binocular stages of the visual processing. We manipulated the 3-D configurations (slant direction) of the target and mask and measured the differential disruption that masking causes on brightness estimation. We found that the masking effect was weaker when stimuli had a different slant. We suggest that brightness masking is partly mediated by mid-level neuronal mechanisms, at a stage where binocular disparity edge structure has been extracted.

A Primary Research on Marine Magnetic Disturbance Correction Method Using Uncombined Precise Point Positioning

ABSTRACT Luo, X.; Gao, J.; Jin, X.; Li, J., and Chu, F., 2015. A primary research on marine magnetic disturbance correction method using uncombined precise point positioning. Marine magnetic survey is an important mean of geophysical exploration. The magnetic disturbance magnitude, the start and end time, and perfecting magnetic disturbance model are important for magnetic survey. In this paper, on the basis of that dual-frequency GNSS is able to get the ionospheric total electron content, reflect the nature of the magnetic disturbance characteristics, etc. the study of magnetic disturbance correction in marine magnetism measurements using dual-frequency GNSS is carried out. Through quality controlled by the dual-frequency GNSS phase observations, ionospheric total electron content solved by static and dynamic at slant direction. Comparing the solving with geomagnetic observatories and marine magnetic measurements, the solution showed that there is relatively strong correlation between ionospheric total e...

From the archives of scientific diplomacy: science and the shared interests of Samuel Hartlib's London and Frederick Clodius's Gottorf.

Many historians have traced the accumulation of scientific archives via communication networks. Engines for communication in early modernity have included trade, the extrapolitical Republic of Letters, religious enthusiasm, and the centralization of large emerging information states. The communication between Samuel Hartlib, John Dury, Duke Friedrich III of Gottorf-Holstein, and his key agent in England, Frederick Clodius, points to a less obvious but no less important impetus--the international negotiations of smaller states. Smaller states shaped communication networks in an international (albeit politically and religiously slanted) direction. Their networks of negotiation contributed to the internationalization of emerging science through a political and religious concept of shared interest. While interest has been central to social studies of science, interest itself has not often been historicized within the history of science. This case study demonstrates the co-production of science and society by tracing how period concepts of interest made science international.

Flame spread over electrical wire with AC electric fields: Internal circulation, fuel vapor-jet, spread rate acceleration, and molten insulator dripping

The effect of electric field on the characteristics of flame spread along a polyethylene (PE) insulated electrical wire was investigated experimentally by varying the AC frequency and voltage applied to the wire. The results showed that the flame spread rate was accelerated due to the convergence of electric flux near the end of wire, having three distinct regimes depending on applied voltage. In each regime, several subregimes could be identified depending on AC frequency. Flame shape (height and width) and slanted direction of the spreading flame were influenced differently. Fuel-vapor jets were ejected from the molten PE surface even for the baseline case without the application of an electric field; this could be attributed to the bursting of fuel vapor bubbles generated from internal boiling at the molten PE surface. An internal circulation of molten-PE was also observed as a result of non-uniform heating by the spreading flame. In the high voltage regime with a high AC frequency, excessive dripping of molten PE led to flame extinction.