Performance Testing on Vector vs. Raster Map Tilesxe2x80x94Comparative Study on Load Metrics Recent developments in web map applications have widely affected how background maps are rendered. Raster tiles are currently considered as a regular solution, while the use of vector tiles is becoming more widespread. This article describes an experiment to test both raster and vector tile methods. The concept behind raster tiles is based on pregenerating an original dataset including a customized symbology and style. All tiles are generated according to a standardized scheme. This method has a few disadvantages: if any change in the dataset is required, the entire tilegenerating process must be redone. Vector tiles manipulate vector objects. Only vector geometry is stored on the server, while symbology, rendering, and defining zoom levels run on the clientside. This method simplifies changing symbology or topology. Based on eight pilot studies, performance testing on loading time, data size, and the number of requests were performed. The observed results provide a comprehensive comparison according to specific interactions. More data, but only one or two tiles, were downloaded for vector tiles in zoom and move interactions, while 40 tiles were downloaded for raster tiles for the same interactions. Generally, the WebP format downloaded about three times fewer data than Portable Network Graphics (PNG).

Interactive browsing of 3D environment over the internet In this paper, we describe a system for wandering in a realistic environment over the Internet. The environment is captured by the concentric mosaic, compressed via the reference block coder (RBC), and accessed and delivered over the Internet through the virtual media (Vmedia) access protocol. Capturing the environment through the concentric mosaic is easy. We mount a camera at the end of a level beam, and shoot images as the beam rotates. The huge dataset of the concentric mosaic is then compressed through the RBC, which is specifically designed for both high compression efficiency and justintime (JIT) rendering. Through the JIT rendering function, only a portion of the RBC bitstream is accessed, decoded and rendered for each virtual view. A multimedia communication protocol  the Vmedia protocol, is then proposed to deliver the compressed concentric mosaic data over the Internet. Only the bitstream segments corresponding to the current view are streamed over the Internet. Moreover, the delivered bitstream segments are managed by a local Vmedia cache so that frequently used bitstream segments need not be streamed over the Internet repeatedly, and the Vmedia is able to handle a RBC bitstream larger than its memory capacity. A Vmedia concentric mosaic interactive browser is developed where the user can freely wander in a realistic environment, e.g., rotate around, walk forwardbackward and sidestep, even under a tight bandwidth of 33.6 kbps.