Changeset 6423 for trunk/gsdl3/web
- Timestamp:
- 2004-01-12T08:53:38+13:00 (20 years ago)
- File:
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- 1 edited
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trunk/gsdl3/web/sites/localsite/collect/nzmaps/etc/collectionConfig.xml
r6296 r6423 7 7 <displayItemList> 8 8 <displayItem name='name' lang='en'>Historic New Zealand Map Collection</displayItem> 9 <displayItem name='description' lang='en'>A collection of Historic New Zealand maps.</displayItem> 9 <displayItem name='description' lang='en'><h3>About this collection</h3> 10 <p>This is a small collection of New Zealand maps drawn between 1770 and 1953. This collection demonstrates map searching and the 11 use of dynamic image manipulation.</p> 12 <p>The collection uses a list of place names from <a href="http://www.linz.govt.nz/">Land Information New Zealand 13 (LINZ)</a> with more than 40,000 entries covering the mainland of New Zealand. The maps were supplied by the <a href=" 14 http://www.waikato.ac.nz/library">University of Waikato Library</a>.</p> 15 <h3>How the collection works</h3> 16 <p><b>Metadata. </b>The maps have an associated metadata file that gives the file name for the image, the latitude and 17 longitude of the top left corner and the bottom right corner of the map, the angle in degrees that North is form the top of the map, and 18 the year the map was drawn. The place names are stored in a hashtable with the place name, the description code, the district code, and 19 the latitude and longitude for each place name.</p> 20 <p><b>Searching. </b>Searching is handled by the MapQuery service. For each query term that exists in the place name 21 hashtable, its longitude and latitude are checked against each map to see if they fall within the bounds of that map. If it is within the 22 bounds of the map, the metadata for the query term is appended to the metadata of the map added to a list. Once all checking is complete, 23 the list is sorted by the number of query terms on each map.</p> 24 <p><b>Image Manipulation and Results Display. </b>Image manipulation and results display is handled by the MapRetrieve 25 service. MapRetrieve uses the longitude and latitude of the place names, with the longtitude and latitude of the corners of the map to 26 calculate where on the image the place is. The convert command (part of the <a href=" 27 http://www.imagemagick.org">ImageMagick</a> suite) is used to make a copy of the map image, and then for drawing an 'x' on the 28 map for each place name and storing the image as a new image. Then the image is resized using ImageMagick. To run the service you must 29 have ImageMagick installed on your server.</p> 30 <p><b>Point selection on a map. </b>When the user click on the map, javascript creates a URL that includes the pixels of 31 the map that were clicked, and this is used to create a window listing all place names near to the point on the map where the mouse-click 32 occurred. This is done using a KD-tree (where the root node branches on the latitude co-ordinate, and then alternately on the longitude 33 co-ordinate) to find the set of places that fall within the given rectangle in the plane. Run-time for this is very efficient, 34 theoretically O(sqrt(<i>n</i>)+<i>k</i>) time where <i>n</i> is the number of points in the tree and 35 <i>k</i> is the number of points in the result.</p> 36 <p><b>Javascript. </b>The collection uses javascript on the content pages for the drop down box to add locations and for 37 the radio buttons to change zoom. This simply removes the need for extra buttons on the page.</displayItem> 10 38 <displayItem name='icon' lang='en'>map.gif</displayItem> 11 39 </displayItemList>
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