Posts Tagged ‘ER Mapper’

Displaying WMS Layers in Google Maps

Wednesday, June 18th, 2008

Image Web Server from ER Mapper offers a WMS reflector that lets you request pieces of JPEG 2000 and ECW images. The trick was to get that WMS data into a Google Maps interface.

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Image Tile Caching

Wednesday, June 18th, 2008

Update (Oct 2, 2009): I’ve written a new post with links to newer versions of this script. Make sure you use the code there, not here.

For the map mosaic viewer I’m working on, the images are generated by ER Mapper’s Image Web Server from the source JPEG 2000 and ECW files. It works great, but can be a little slow, as it has to load very large images (equivalent of 100GB uncompressed) and pull tiles out. Because the viewer always uses the same tiles at each zoom level (defined by a lat/lon bounding box), it made sense to cache the images.

A real simple PHP file seemed to do the trick:

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Mosaics of Old Maps

Wednesday, May 14th, 2008

One of the really cool projects that I get to work on is building indexes and access systems for the various maps that become part of the Greater Philadelphia GeoHistory Network. (In case you don’t want to read the rest, just check out the beginnings of something I’m working on. View the map, then click “LUM 1942.”)

Many of the maps that were scanned so far are from old atlases, ranging from 1858 through the early 1900s. Then there are two sets of land use survey maps that were produced by the Works Progress Administration in 1942 and 1962. (Wikipedia says that the WPA was shut down by Congress in 1943, so I’m not sure where the 1962 set came from, but that’s what the title sheet says…)

Anyway, I’ve been having fun with the 1942 set of the Land Use Maps. The maps are arranged in a grid of 100 plates that covers Philadelphia, and are pretty straightforward to navigate. But in this modern day and age where Google offers a seamless coverage of the whole earth, who wants to flip through individual plates?

Enter the mosaic.

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