Zhenlin Cheng

Fast map projection on CUDA

Map projection is a key task in cartography that transforms the geographical coordinates from one coordinate system to another. It has been widely used in the Geographic Information System application. However, map projection is a very time-consuming task, and fast processing speed is often required in interactive GIS scenarios. Parallel computation provides an opportunity to reduce run times. Nowadays, with the Common Unified Device Architecture (CUDA) becoming a new programming approach of the general purpose computing on graphics processing units (GPGPU), map projection can be accelerated by fully utilizing the computing power of this revolutionary technology. In this paper, we present an innovative implementation of this compute-intensive operation. We also explain the parallel characteristics of the graphics processing units (GPU) through the work assignment. The result shows our optimized implementation can obtain at least 6× to 8× speedups over a very similar single-threaded CPU implementation.

VegaMinerPOI: A spatial data mining system for POI datasets

During the past few years Special-purpose data mining systems have drawn great attraction in research and industry area for their application into real environments. In this paper, a new scalable spatial data mining architecture for POI(Points of Interest) datasets has been proposed on VegaGIS 3.0 platform to design and develop a professional spatial data mining system. Our research covers a wide spectrum of knowledge discovery, including: knowledge discovery and data mining process model, interface standards and language standards. The interface and architecture of some commercial spatial data mining system such as Oracle Data Mining (ODM) are also examined.

One rasterization approach algorithm for high performance map overlay

It is a critical technique in GIS about how to implement map overlay with high performance. To avoid the disadvantages of computational geometry algorithm approach, an optimal algorithm based on rasterization is proposed in this paper, which adopts approach of rasterization of vector polygons with run length encoded scan line, map overlay on the basis of raster representation and vectorization of binary raster data with improved boundary tracing method. Experiments show the significant performance and efficiency improvements of the proposed algorithm, which is one promising solution for the map overlay function of on-line map service system taking the approach of pre-rendered raster tiles with predefined map scales.

One rasterization approach to spatial predicate

How to provide cost effective, high performance spatial relation/spatial predicate implementation is one important issue for internet map server design. To avoid the disadvantages of computational geometry algorithm approach, it proposes one improved method, combined with the rendering engine, which can enhance the filter accuracy. This proposal can record coverage area of border grid cells accurately based on subpixel accuracy, so it can determine spatial relation through judging coverage area of the corresponding grid cells. As side effects, the rendering engine can preserve feature attribute information (polygon IDs etc.) in the cell structure which offers more useful hints for spatial relation judgment. The prototype adopting the above methods is presented and the related benchmark result details reveal the effectiveness and efficiency of the proposal.

One rasterizaiton spatial index for Internet map server

The spatial index method is one critical factor affecting the query performance in the case of web feature service. The R-tree method, which is one popular method used in spatial database, has limitations for web feature service. In this paper, we propose one rasterization spatial index method utilizing AGG as the engine for the mapping between geographic features and image pixels. After illustrating the design and implementation of this method, we conduct experiments to compare the performance of R-tree and the proposed method. The result shows that the significant performance advantage (about 22%) of the new method.

Spatial predicate implementation for modern internet map server

It is a critical technique in GIS about how to implement spatial relation/spatial predicate with high performance. To avoid the disadvantages of computational geometry algorithm approach, we propose one improved method, combined with the rendering engine, which can enhance the filter accuracy and avoid drawbacks of four color raster signature (4CRS). This proposal can record coverage area of border grid cells accurately based on subpixel accuracy, so it can determine whether two polygons overlap through judging coverage area of the corresponding grid cells. As side effects, the rendering engine can preserve feature attribute information(polygon IDs etc.) in the cell structure which offers more useful hints for spatial relation judgment.

One rasterization approach to high performance internet map server design and implementation

How to provide cost effective, high performance spatial query and spatial analysis implementation is one important issue for internet map server design. In this paper, we present one novel, rasterization approach to internet map server design and implementation. Like most modern internet map server implementation, this system stores pre-rendered map image tiles for different scales on the web server, which are then laced together on the client browser. The key issues and rasterization solutions of spatial query, spatial predicate and spatial analysis are proposed and illustrated in this paper. Furthermore, the key details of the algorithm design are presented in this paper. The prototype adopting the above methods is presented and the related benchmark result details reveal the effectiveness and efficiency of the proposal.