A progressive vector map browser for the web

Abstract

Abstract:With the increasing popularity of web-based map browsers, remotely obtaining a high quality depiction of cartographic information has become commonplace. Most web mapping systems, however, rely on high-capacity servers transmitting pre-rendered tiled maps in raster format. That approach is capable of producing good quality renderings on the client side while using limited bandwidth and exploiting the browser's image cache. These goals are harder to achieve for maps in vector format. In this work, we present an alternative client-server architecture capable of progressively transmitting vector maps in levels-of-detail (LOD) by using techniques such as polygonal line simplification, spatial data structures and, most importantly, a customized memory management algorithm. A multiplatform implementation of this system is described, where the client application is written entirely in JavaScript and processed within the web browser, avoiding the need of external applications or plug-ins. Results of experiments aimed at gauging both the performance and the display quality obtained with the system are presented and explained. Extensions to the system are also discussed, including issues such as level-of-detail versus visual importance tradeoffs and the handling of closed polygonal lines.

GeohashTile: Vector Geographic Data Display Method Based on Geohash

“…Using a spatial index to manage and maintain the tile pyramid has important application value, and its performance directly affects the overall performance of geographic information network services. Grid index and quadtree index are widely used spatial indexing methods in the tile pyramid model [22][23][24].…”

“…In terms of coordinate representation, almost all of them are represented by latitude and longitude; in terms of indexing methods, except for the inverted index mode adopted by Zouhar et al [9], all other methods belong to quadtree mode. However, due to the different encoding methods, there are different kinds of quadtree modes: from the perspective of the projection method, except for the method not explicitly stated in the article, the others use web Mercator projection; as far as the intermediate result caching is concerned, since there is no relative position projection method used in these methods, there is no function involving the relative position intermediate result caching; from the scope of application, except for Zouhar et al which is only applicable to polygon data, and Ramos et al [24], which is only applicable to polygonal lines data, other methods apply to all basic vector map data. [8] Latitude and longitude Quadkey Quadtree Web Mercator no All basic vector maps Zouhar et al [9] Latitude and longitude Inverted Index Web Mercator Not mentioned Polygon wan et al [25] Latitude and longitude Quadtree Not mentioned Not mentioned All basic vector maps Ramos et al [24] Not mentioned MX-CIF Quadtree Not mentioned No Polygonal lines GeoTile [2] Latitude and longitude XYZ Quadtree Web Mercator No All basic vector maps Proposed Approach Geohash Geohash Relative position Yes All basic vector maps…”