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We explore the notion of a Well-spaced Blue-noise Distribution (WBD) of points, which combines two desirable properties. First, the point distribution is random, as measured by its spectrum having blue noise. Second, it is well-spaced in the sense that the minimum separation distance between samples is large compared to the maximum coverage distance between(More)
Oxygen-18 ((18)0) and deuterium isotopes were used to estimate the evaporation from the Aswan High Dam Lake and to investigate the inter-relation between the lake water and adjacent groundwater.According to stable isotopic analysis of samples taken in 1988 and 1989, the lake can be divided into two sections. In the first section extending between Abu Simbel(More)
Blue noise refers to sample distributions that are random and well-spaced, with a variety of applications in graphics, geometry, and optimization. However, prior blue noise sampling algorithms typically suffer from the curse-of-dimensionality, especially when striving to cover a domain maximally. This hampers their applicability for high dimensional(More)
We review our recent progress on efficient algorithms for generating well-spaced samples of high dimensional data, and for exploring and characterizing these data, the underlying domain, and functions over the domain. To our knowledge, these techniques have not yet been applied to computational topology, but the possible connections are worth considering.(More)
Figure 1: A sifted point cloud (right) retains much of the visual quality of the original (left), but using fewer points. 113k points were reduced by 16% in 19 seconds. Sifted disks are maximal and satisfy the same sizing function as the original. Abstract We introduce the Sifted Disk technique for locally resampling a point cloud in order to reduce the(More)
Poisson-disk sampling is similar to sphere packings: points have a minimum separation distance and the disks cover the domain. Disk centers are randomly placed. The method is popular in computer graphics because the random distribution avoids visual artifacts. This randomness can also be useful to avoid mesh-induced non-physical phenomena in simulations. We(More)
We introduce an algorithmic framework for tuning the spatial density of disks in a maximal random packing, without changing the sizing function or radii of disks. Starting from any maximal random packing such as a Maximal Poisson-disk Sampling (MPS), we iteratively relocate, inject (add), or eject (remove) disks, using a set of three successively(More)
Chemical and isotopic investigations indicate that the recharge source for the groundwater in the Tahta district, adjacent to the Nile, is mainly from the Nile water seeping from irrigation channels. The water's chemical type is sodium bicarbonate, with values of oxygen-18 and deuterium close to that of Nile water. Another minor source of recharge to the(More)
The EI-Dabaa area is located on the northwestern coastal zone of Egypt and is considered to be one of the most important regions for land reclamation and agriculture. In addition, it has been selected as a potential site for constructing Egypt's first nuclear power plant.In April 1989, 14 groundwater samples were collected from the area as well as(More)
The groundwater resources of the El-Qusier-Safaga area on the Red Sea coastal zone have still to be utilised fully for social and economic development. In the present study, an inventory of recharge sources and quality of groundwater in different water bearing formations is made to assist in management of these vital resources. From a hydrochemical point of(More)