>> Blog home What is ECWP?
June 09, 2009
ECWP is a high-speed streaming imagery protocol provided by Image Web Server.
ECWP allows a single, entry-level server, to provide 1000's of gigabytes of image data to thousands of concurrent users that are using different web, desktop, GIS, server or mobile applications.
ECWP achieves this level of efficiency by transferring compressed imagery data from the server to the client. The client application then decompresses these image blocks. This provides the client a real-time roam and zoom experience, as well as reducing the total datasize sent to the client.
The server also uses some intelligence when sending data to the client so that subsequent image views load even faster than the first. This, combined with client-side caching means that the more you use the imagery, the faster is arrives.
At the server-end, the server finds this sort of data delivery very easy. Using ECWP, a server doesn't have to "subset" an image, and render it as a JPEG or PNG file, as would be the case of a WMS based delivery. This subsetting approach is very processor intensive.
A single Image Web Server server can sustain over 5,000 connections to very large volumes of data. Again, this is only on a modest hardware system.
Many applications natively support ER Mapper’s streaming imagery protocol. For example, MapInfo and ERDAS IMAGINE. For other applications, there are many free plug-ins available. The plug-in for ArcGIS Desktop and AutoCAD are particularly popular.
For web browsers, a small "plug-in" installation is required to read ECWP data.
ECWP serves both ECW and JPEG 2000 image files. Both of these file formats are "wavelet" based, allowing for high-levels of image compression without adversely affecting the visual quality of the image files. For example, a file may be compressed to just 5% of its original file size with little or no difference in the visual quality.
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