For efficient retrieval and display of Digital Nautical Chart (DNCÃÂî) imagery, a tiled-based approach is presented. By preprocessing the data into persistent image tiles, the presented method can minimize or eliminate image processing steps during the retrieval process. Tile-based approaches define constant image sizes and scales for geographic regions, therefore tiles can be pre-generated and stored in a format needed for transmission to users. This greatly improves the performance of applications that visualize DNCÃÂî data and allows for advanced caching of DNCÃÂî imagery tiles. In addition, the evenly-spaced and commonly-sized images are stored in files that are easily indexed allowing for simple and fast lookup of DNCÃÂî imagery tiles for a given geographic area.
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