Pairs Of Tiles Research Articles

Image Matching by Bare Homography.

This paper presents Slime, a novel non-deep image matching framework which models the scene as rough local overlapping planes. This intermediate representation sits in-between the local affine approximation of the keypoint patches and the global matching based on both spatial and similarity constraints, providing a progressive pruning of the correspondences, as planes are easier to handle with respect to general scenes. Slime decomposes the images into overlapping regions at different scales and computes loose planar homographies. Planes are mutually extended by compatible matches and the images are split into fixed tiles, with only the best homographies retained for each pair of tiles. Stable matches are identified according to the consensus of the admissible stereo configurations provided by pairwise homographies. Within tiles, the rough planes are then merged according to their overlap in terms of matches and further consistent correspondences are extracted. The whole process only involves homography constraints. As a result, both the coverage and the stability of correct matches over the scene are amplified, together with the ability to spot matches in challenging scenes, allowing traditional hybrid matching pipelines to make up lost ground against recent end-to-end deep matching methods. In addition, the paper gives a thorough comparative analysis of recent state-of-the-art in image matching represented by end-to-end deep networks and hybrid pipelines. The evaluation considers both planar and non-planar scenes, taking into account critical and challenging scenarios including abrupt temporal image changes and strong variations in relative image rotations. According to this analysis, although the impressive progress done in this field, there is still a wide room for improvements to be investigated in future research.

NeuSB: A Scalable Interconnect Architecture for Spiking Neuromorphic Hardware

Neuromorphic systems are typically designed as a tile-based architecture where inter-tile data communication is facilitated using a shared global interconnect. Congestion on this interconnect can increase both interconnect energy, which increases the total energy consumption of the hardware and latency, which impacts the performance e.g., accuracy of the application that is being executed on the hardware. Mesh-based Network-on-Chip (NoC) that is used in most hardware prototypes is not the optimal interconnect solution for neuromorphic systems. This is because of the following two reasons. First, power consumption and average latency of a NoC increases exponentially with the number of tiles in the hardware. Second, a NoC cannot exploit an application’s data communication pattern efficiently. Once designed for a target hardware, the bandwidth on each NoC link stays the same, independent of the volume of data traffic between different tile pairs of the NoC. In other words, a NoC cannot be customized at a finer granularity based on an individual application running on the hardware. We show that these NoC limitations prevent opportunities to further improve energy and latency of a neuromorphic hardware. To address these limitations, we propose Dynamic Segmented Bus (SB) interconnect for neuromorphic systems. Here, a bus lane is partitioned into segments with each segment connecting a few tiles. Connection of tiles to segments and those between segments are bridged using our novel three-way segmentation switches that are programmed using the software before admitting an application to the hardware. We partition an application by analyzing its workload and place partitions intelligently onto segments. This exploits application characteristics to use the segments without any routing collisions while exploiting the latency and energy savings in the design-time mapping phase. At a high-level, our mapping algorithm places tiles that communicate the most on shorter segments utilizing fewer number of switches, thereby reducing network congestion. It can adjust the bandwidth by controlling the number of segments connected to a destination tile. At run time, our controller dynamically executes the predefined routing paths without requiring any additionally routing decisions, unlike a NoC. This allows us to improve both energy and latency. Using parallel segmented busses, our proposed interconnect architecture can support a large number of tiles without significantly increasing the design cost, energy, and latency. Simulation results show that compared to the most widely-used mesh-based NoC design, our interconnect architecture, which we call NeuSB, reduces the switch area by 20x, average interconnect energy by 6.2x, and latency by 23%.

Broadband Metasurface Absorber Based on an Optimal Combination of Copper Tiles and Chip Resistors

In this study, a broadband metasurface absorber composed of an optimal combination of copper tiles connected with four chip resistors is designed and experimentally verified. After fixing the locations of the chip resistors and setting their resistances to 100 Ω, the genetic algorithm (GA) is utilized to design the optimal copper tile pattern for broadband absorption. The optimal combination of the copper tiles is identified by determining the states of the square tile pairs between copper or air, depending on the one or zero states of the bit sequence created by GA, respectively. The full-wave simulation results of the optimized metasurface absorber confirmed a -10 dB reflectance bandwidth within the frequency range of 6.57 to 12.73 GHz for the normal incidence condition, with the fractional bandwidth being 63.83%. The accuracy of the metasurface absorber was verified through an experimental result that matched well with the full-wave simulated one.

Digital geometry on a cubic stair-case mesh

• The cubic grid Z 3 plays important role in the (digital) world. • Meshes obtained by cutting Z 3 by oblique planes can display 2d images. • The dual semi-regular grid, the rhombille tiling is an oblique cubic mesh. • Shortest path algorithm and digital distance are computed on the rhombille tiling. • The rhombille tiling can be used as a digital canvas and for RGB pixel geometry. In this paper, we investigate digital geometry on the rhombille tiling, D(6,3,6,3), that is the dual of the semi-regular tiling called hexadeltille T(6,3,6,3) tiling and also known as trihexagonal tiling. In fact, this tiling can be seen as an oblique mesh of the cubic grid giving practical importance to this specific grid both in image processing and graphics. The properties of the coordinate systems used to address the tiles are playing crucial roles in the simplicity of various algorithms and mathematical formulae of digital geometry that allow to work on the grid in image processing, image analysis and computer graphics, thus we present a symmetric coordinate system. This coordinate system has a strong relation to topological/combinatorial coordinate system of the cubic grid. It is an interesting fact that greedy shortest path algorithm may not be used on this grid, despite to this, we present algorithm to provide a minimal-length path between each pair of tiles, where paths are defined as sequences of neighbor tiles (those are considered to be neighbors which share a side). We also prove closed formula for computing the digital, i.e., path-based distance, the length (the number of steps) of a/the shortest path(s). Some example pictures on this grid are also presented, as well as its possible application as pixel geometry for color images and videos on the hexagonal grid. To create your abstract, type over the instructions in the template box below. Fonts or abstract dimensions should not be changed or altered.

Unbiased Seamless SAR Image Change Detection Based on Normalized Compression Distance

Land cover changes may have very different nature, e.g., vegetation development, soil erosion, variation of humidity, or damage of buildings, only to enumerate few cases. In addition, synthetic aperture radar (SAR) observations are a doppelganger of the scene, imaging the scene signature rather than the scene itself. To overcome these challenges, SAR change detection methods generally adapt to the particular situations. We present seamless methods based on normalized compression distance (NCD) estimation. NCD is a similarity metric applied directly to the data, thus with no biases induced by feature estimators or classifiers. Since the diversity of changes is huge and extremely hard to derive typical classes, we introduce paradigm based both on an unsupervised and a supervised method. The change detection procedure mainly consists in dividing image dataset in patches, computing a collection of similarities for pairs of tiles formed differently in each case, and usage of this collection in unsupervised and supervised forms to generate a change map. Both the threshold based histogram, unsupervised method, and the k-NN classifier algorithm, supervised method, have a distinct flow to obtain the change map. To use the NCD operator according to our proposed methods, a speckle resistance test is involved. The experimental results for the two methodologies are computed using two TerraSAR-X images over Sendai and surrounding areas, Japan.

A Novel Markerless Lung Tumor-Tracking Method Using Treatment MV Beam Imaging

A novel method was developed to track lung tumor motion in real time during radiation therapy with the purpose to allow target radiation dose escalation while simultaneously reducing the dose to sensitive structures, thereby increasing local control without increasing toxicity. This method analyzes beam’s eye view radiation therapy treatment megavoltage (MV) images with simulated digitally reconstructed radiographs (DRRs) as references. Instead of comparing global DRRs with projection images, this method incorporates a technique that divides the global composite DRR and the corresponding MV projection into sub-images called tiles. Registration is performed independently on tile pairs in order to reduce the effects of global discrepancies due to scattering or imaging modality differences. This algorithm was evaluated by phantom studies while simulated tumors were controlled to move with various patterns in a complex humanoid torso. Approximately 15,000 phantom MV images were acquired at nine gantry angles, with different tumors moving within ranges between 10 and 20 mm. Tumors were successfully identified on every projection with a total maximum/average error of 1.84/0.98 mm. This algorithm was also applied to over 5,000 frames of MV projections acquired during radiation therapy of five lung cancer patients. This tumor-tracking methodology is capable of accurately locating lung tumors during treatment without implanting any internal fiducial markers nor delivering extra imaging radiation doses.

Tile Pair-Based Adaptive Multi-Rate Stereo Shading.

This work proposes a new stereo shading architecture that enables adaptive shading rates and automatic shading reuse among triangles and between two views. The proposed pipeline presents several novel features. First, the present sort-middle/bin shading is extended to tile pair-based shading to rasterize and shade pixels at two views simultaneously. A new rasterization algorithm utilizing epipolar geometry is then proposed to schedule tile pairs and perform rasterization at stereo views efficiently. Second, this work presents an adaptive multi-rate shading framework to compute shading on pixels at different rates. A novel tile-based screen space cache and a new cache reuse shader are proposed to perform such multi-rate shading across triangles and views. The results show that the newly proposed method outperforms the standard sort-middle shading and the state-of-the-art multi-rate shading by achieving considerably lower shading cost and memory bandwidth.

Implementasi Algoritma Greedy pada Pencarian Langkah Optimal Permainan Mahjong Solitaire

The game of mahjong solitaire is a difficult tough teaser and takes a long time to complete when manually played by the user. The greedy algorithm is applied to find the optimal step in completion of this solitaire mahjong game. The algorithm used in this research is greedy algorithm. The result of this research is game of mahjong solitaire with 5 model of tile arrangement where game can be completed manually or automatically by greedy algorithm. The greedy algorithm is applied to compare the acquisition of the most tile pairs in the 1 step forward when 1 pair of tiles is removed. The conclusion of this study is from 250 times testing of 5 levels of the game where the test at each level as much as 50 times, obtained the victory as much as 168 times and defeat as much as 82 times. So the percentage of success of greedy algorima in completion of game of solitaire mahjong is 67.2%. While in manual testing, from 250 times the test of 5 levels of the game where the test at each level as much as 50 times by 5 players, obtained 161 victories and defeat 89 times. So the percentage of success of greedy algorima in game settlement is 64.4%.

Recruitment failure of scleractinian corals in a subtropical marginal environment: Three-year monitoring in a Hong Kong marine park

Coral recruitment was monitored for three years, using terracotta tiles, in two core coral areas in Tung Ping Chau Marine Park where coral coverage is one of the richest in Hong Kong. Results revealed an extremely low recruitment success of corals, with only 10 recruits recorded on 384 tile pairs, equivalent to 0.19 recruits m−2yr−1 throughout the study period. Recruits of Platygyra acuta pre-seeded on tiles that were subsequently grown in situ experienced very high mortality following settlement, with average mortality of 80% within half a month and <0.1% survival through the first four months of deployment. Data suggested that low recruitment of corals may be due to the lack of arrival of competent coral larvae, low larval settlement; and/or low post-settlement survival of recruits due to high sedimentation or intense competition for space with fouling organisms, e.g. algae, oysters, barnacles and bryozoans, which may negatively affect coral recruitment.

Global error minimization in image mosaicing using graph connectivity and its applications in microscopy

Several applications such as multiprojector displays and microscopy require the mosaicing of images (tiles) acquired by a camera as it traverses an unknown trajectory in 3D space. A homography relates the image coordinates of a point in each tile to those of a reference tile provided the 3D scene is planar. Our approach in such applications is to first perform pairwise alignment of the tiles that have imaged common regions in order to recover a homography relating the tile pair. We then find the global set of homographies relating each individual tile to a reference tile such that the homographies relating all tile pairs are kept as consistent as possible. Using these global homographies, one can generate a mosaic of the entire scene. We derive a general analytical solution for the global homographies by representing the pair-wise homographies on a connectivity graph. Our solution can accommodate imprecise prior information regarding the global homographies whenever such information is available. We also derive equations for the special case of translation estimation of an X-Y microscopy stage used in histology imaging and present examples of stitched microscopy slices of specimens obtained after radical prostatectomy or prostate biopsy. In addition, we demonstrate the superiority of our approach over tree-structured approaches for global error minimization.

Erosion and re-deposition processes in JET tiles studied with ion beams

Abstract Plasma facing components in fusion reactor chambers will operate under extreme conditions. Among the processes with implications on the material lifetime are erosion and re-deposition due to plasma interactions. This work will address the behaviour of both JET divertor and outer poloidal limiters (OPL) under plasma irradiation. The limiters comprise about 50 pairs of tiles in a poloidal stack, each of which has a plasma facing surface about 25 mm (poloidal) by 350 mm (toroidal) and is about 50 mm thick. The divertor tiles are located at the bottom of the chamber and withstand high fluxes of radiation and heat. Standard carbon-fibre composite (CFC) tiles coated with a thin layer of W overlaid with a 10 μm layer of C were studied with RBS/PIXE to understand the erosion/re-deposition processes occurring in these regions of the reactor chamber. High resolution surface morphology was assessed through SEM with and without tilting of the sample. The retention of hydrogen isotopes in the tiles were studied combining NRA and ERDA techniques – this is mostly 2H from the fuelling gas, but 3H is also present as a result of 2H–2H fusion reactions, and 1H coming from the atmospheric exposure.

Tiling a Polygon with Two Kinds of Rectangles

We fix two rectangles with integer dimensions. We give a quadratic time algorithm which, given a polygon F as input, produces a tiling of F with translated copies of our rectangles (or indicates that there is no tiling). Moreover, we prove that any pair of tilings can be linked by a sequence of local transformations of tilings, called flips. This study is based on the use of Conway’s tiling groups and extends the results of Kenyon and Kenyon (limited to the case when each rectangle has a side of length 1).

The effects of fungal inoculum arrangement (scale and context) on emergent community development in an agar model system

Consequences of initial spatial organisation of model fungal communities upon their spatio-temporal development were investigated. Dynamics of prescribed two- and three-species ‘communities’ developing on tessellated agar tile model systems were analysed in terms of literal maps, principal component analyses, or as the proportion of species extant within tiles. It was established that for two-species interactions of equal patch size, large-scale (i.e. many constituent tiles) behaviour could be extrapolated from the relevant small-scale (i.e. pairs of tiles) interactions. However, relative patch sizes (scale) of species within tessellations influenced the times taken by individuals to colonise tiles and, hence, temporal behaviour of the system. Outcome of arrangements involving three species of equal patch size and inoculum potential, and prescribed with different mixing patterns, could not be directly extrapolated by reference to the outcome of pair-wise interactions between constituent species. Three-species arrangements attempt to limit assembly of lateral aggregates of individuals (patch size) and hence any effects of tile colonisation times, so as to reveal effects of nearest neighbour context within the complex community. Such arrangements indicate that spatial configuration of inoculum influences community development and reproducibility. They also suggest that spatial distribution of species affects persistence of individuals, which would otherwise be expected to be eliminated from the system. Two-species interactions appeared generally more reproducible than those comprising three species, and the sensitivity of fungal community development to temperature was not solely associated with influence on colony extension rate.

The effects of fungal inoculum arrangement (scale and context) on emergent community development in an agar model system

Abstract Consequences of initial spatial organisation of model fungal communities upon their spatio-temporal development were investigated. Dynamics of prescribed two- and three-species 'communities' developing on tessellated agar tile model systems were analysed in terms of literal maps, principal component analyses, or as the proportion of species extant within tiles. It was established that for two-species interactions of equal patch size, large-scale (i.e. many constituent tiles) behaviour could be extrapolated from the relevant small-scale (i.e. pairs of tiles) interactions. However, relative patch sizes (scale) of species within tessellations influenced the times taken by individuals to colonise tiles and, hence, temporal behaviour of the system. Outcome of arrangements involving three species of equal patch size and inoculum potential, and prescribed with different mixing patterns, could not be directly extrapolated by reference to the outcome of pair-wise interactions between constituent species. Three-species arrangements attempt to limit assembly of lateral aggregates of individuals (patch size) and hence any effects of tile colonisation times, so as to reveal effects of nearest neighbour context within the complex community. Such arrangements indicate that spatial configuration of inoculum influences community development and reproducibility. They also suggest that spatial distribution of species affects persistence of individuals, which would otherwise be expected to be eliminated from the system. Two-species interactions appeared generally more reproducible than those comprising three species, and the sensitivity of fungal community development to temperature was not solely associated with influence on colony extension rate.

Settlement-competency periods of larvae of three species of scleractinian corals

The pattern of settlement over time of three broadcast spawning coral species (Cyphastrea serailia, Acanthastrea lordhowensis, and Goniastrea australensis) from the Solitary Islands (30°00′S; 153°20′E) was studied in 1995 and 1996 in order to determine the maximum length of time these larvae could remain in the water column and still retain the ability to settle and metamorphose. Larvae were maintained in aquaria and the number which had settled on biologically-conditioned tile pairs was monitored every 5 to 10 d. While the majority of larvae settled quickly after becoming competent, some larvae survived and settled for extended periods after spawning. Competency periods ranged from 26 d for C. serailia to 56 d for G. australensis and 78 d for A. lordhowensis. These data greatly extend the known competency periods for larvae of broadcast-spawning corals and indicate the potential for transport of broadcast-spawned coral larvae over large distances. Medium to long-distance larval dispersal of the species studied provides a mechanism for their widespread distribution in subtropical regions, on reefs which are often widely spaced and relatively isolated.

The Pinwheel Tilings of the Plane

prototiles) in Euclidean n-space, En, for n > 2. The prototiles are usually required to be rather nice topologically, at least homeomorphs of the closed unit ball. One then makes arbitrarily many congruent copies, called tiles, of these prototiles, and considers all ways (called tilings) that such tiles may provide a simultaneous covering and packing of En; a tiling is thus an unordered collection of tiles for which the union is all of En, but such that the interiors of each pair of tiles do not intersect. Wang's original problem was to determine if it was possible to have a finite set of prototiles, with associated tilings of space, for which all the tilings were nonperiodic. (A tiling is nonperiodic if it is not invariant under any single simultaneous translation of its tiles.) This was settled in the affirmative in the thesis of Wang's student Robert Berger [1].

Refined hierarchy of vertices in icosahedral quasicrystals

Imperfect icosahedral quasicrystals are assumed to grow obeying a local rule forcing the twin orientation of like building blocks. The resultant vertex configurations are classified by their energies determined by calculating partial overlaps in their dual images. A previously established hierarchy which took into account only pairs of tiles sharing a face is refined by calculating overlaps of higher orders, in particular, between triples sharing an edge.

Optical transform and Monte-Carlo study of phason fluctuations in quasi-periodic tilings

Monte-Carlo simulations are used together with optical transform methods to investigate the effect of phason fluctuations on the diffraction pattern of some two-dimensional (2D) tilings. From a perfect Penrose tiling phason fluctuations are allowed with probabilities defined by an energy dependent on the types of nearest-neighbour tile pairs, and the degree of disorder that may be introduced and its effect on the diffraction pattern are investigated. It is then possible to generate homogeneous two-dimensional tilings, varying from those showing a high degree of microcrystallinity, through those which are much more random, to others in which, although the local order is altered substantially, the longer-range order present in the Penrose pattern is preserved.

Surface analysis of 1984/85 Tokamak Fusion Test Reactor limiter tiles

Bare POCO AXF-5Q graphite tiles were installed as the plasma-facing surface of the Tokamak Fusion Test Reactor (TFTR) movable limiter for a series of ∼2700 high power discharges (600 with up to 6 MW neutral beams). During this operating phase, erosion and deposition processes modified the surface of the limiter. In the regions of the most intense plasma contact, which reached temperatures over 2400 °C, only small amounts of metallic impurities (&amp;lt;5×1016 atoms/cm2) are observed during subsequent beta backscattering and proton-induced x-ray emission (PIXE) analysis. Also observed in these regions are several small areas of surface crazing, and scattered droplets of metals (∼1 mm diam) presumed to originate from melted internal hardware. In regions more removed from direct plasma contact, thicker metallic deposits are observed (∼2×1018 atoms/cm2). There are more of these deposits on the side facing the electron drift direction than on the ion drift side. The metallic deposits are composed of ∼55% Ni, 25% Cr, and 20% Fe and several trace elements. Near-surface retained deuterium levels vary from 1016 to 1018/cm2 along one ion-side/electron-side pair of tiles. Deuterium from TFTR operations in the bulk of a tile may have been as much as 5 ppm. Hydrogen in the tile was ∼1 at. %. Surface roughness measured outside the intense plasma contact region is much more than the original POCO AXF-5Q graphite, whereas within the plasma contact region, tile surfaces are somewhat smoother than they were initially. Two of the tiles in high heat flux regions broke during operation. The resulting geometry change led to areas of enhanced erosion and nearby redeposition of carbon.

Pairs of tiles which admit finitely or countably infinitely many tilings

For every positive integer r, there exist pairs of prototiles which admit exactly r distinct tilings of the plane. Furthermore, there exist pairs of prototiles which admit a countable infinity of distinct tilings.