A global geographic grid system for visualizing bathymetry

A global geographic grid system (Global GGS) is here introduced to support the display of gridded bathymetric data at whatever resolution is available in a visually seamless manner. The Global GGS combines a quadtree metagrid hierarchy with a system of compatible data grids. Metagrid nodes define the boundaries of data grids. Data grids are regular grids of depth values, coarse grids are used to represent sparse data and finer grids are used to represent high-resolution data. Both metagrids and data grids are defined in geographic coordinates to allow broad compatibility with the widest range of geospatial software packages. An important goal of the Global GGS is to support the meshing of adjacent tiles with different resolutions so as to create a seamless surface. This is accomplished by ensuring that abutting data grids either match exactly with respect to their grid-cell size or only differ by powers of 2. The oversampling of geographic data grids, which occurs towards the poles due to the convergence of meridians, is addressed by reducing the number of columns (longitude sampling) by powers of 2 at appropriate lines of latitude. In addition to the specification of the Global GGS, this paper describes a proof-of-concept implementation and some possible variants.

A Global Geographic Grid System for Visualizing Bathymetry

A Global Geographic Grid System (Global GGS) is here introduced to support the display of gridded bathymetric data at whatever resolution is available in a visually seamless manner. The Global GGS combines a quad-tree metagrid hierarchy with a system of compatible data grids. Metagrid nodes define the boundaries of data grids. Data grids are regular grids of depth values, coarse grids are used to represent sparse data and finer grids are used to represent high resolution data. Both metagrids and data grids are defined in geographic coordinates to allow broad compatibility with the widest range of geospatial software packages. An important goal of the Global GGS is to support the meshing of adjacent tiles with different resolutions so as to create a seamless surface. This is accomplished by ensuring that abutting data grids either match exactly with respect to their grid-cell size or only differ by powers of two. The oversampling of geographic data grids, which occurs towards the poles due to the convergence of meridians, is addressed by reducing the number of columns (longitude sampling) by powers of two at appropriate lines of latitude. In addition to the specification of the Global GGS. This paper describes a proof-of-concept implementation and some possible variants.

Optimization of Replica Consistency and Conflict Resolution in Data Grid Environment

Data replication is widely used mechanism aiming at ensuring efficient access, improving performance and providing quality data in data grids. The properties of file and their replicas can vary with time resulting to inconsistency. In this paper, an agent-based replica consistency approach, namely, Replica Consistency and Conflict Resolution (RCCR) has been proposed to improve the efficiency of the system. RCCR is hybrid approach which is used to address the problem of inconsistency in multi master environment. Additionally, the conflict resolution approach is introduced based on vector clock and version of the replica. Finally, simulated results are presented and compared with existing consistency approaches such as Pessimistic, Optimistic and One-way Replica Consistency (ORCS). The simulated results depicts that proposed RCCR approach performs better when writeable replicas are more likely to occur.