Changeset 6423

Timestamp:

2004-01-12T08:53:38+13:00 (20 years ago)

Author:

kjdon

Message:

added in a description

File:

• trunk/gsdl3/web/sites/localsite/collect/nzmaps/etc/collectionConfig.xml (modified) (1 diff)

trunk/gsdl3/web/sites/localsite/collect/nzmaps/etc/collectionConfig.xml

@@ -7 +7 @@
   <displayItemList>
     <displayItem name='name' lang='en'>Historic New Zealand Map Collection</displayItem>
-    <displayItem name='description' lang='en'>A collection of Historic New Zealand maps.</displayItem>
+    <displayItem name='description' lang='en'>&lt;h3&gt;About this collection&lt;/h3&gt;
+&lt;p&gt;This is a small collection of New Zealand maps drawn between 1770 and 1953.  This collection demonstrates map searching and the
+use of dynamic image manipulation.&lt;/p&gt;
+&lt;p&gt;The collection uses a list of place names from &lt;a href="http://www.linz.govt.nz/"&gt;Land Information New Zealand
+(LINZ)&lt;/a&gt; with more than 40,000 entries covering the mainland of New Zealand.  The maps were supplied by the &lt;a href="
+http://www.waikato.ac.nz/library"&gt;University of Waikato Library&lt;/a&gt;.&lt;/p&gt;
+&lt;h3&gt;How the collection works&lt;/h3&gt;
+&lt;p&gt;&lt;b&gt;Metadata. &lt;/b&gt;The maps have an associated metadata file that gives the file name for the image, the latitude and
+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
+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
+the latitude and longitude for each place name.&lt;/p&gt;
+&lt;p&gt;&lt;b&gt;Searching. &lt;/b&gt;Searching is handled by the MapQuery service.  For each query term that exists in the place name
+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
+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,
+the list is sorted by the number of query terms on each map.&lt;/p&gt;
+&lt;p&gt;&lt;b&gt;Image Manipulation and Results Display. &lt;/b&gt;Image manipulation and results display is handled by the MapRetrieve
+service.  MapRetrieve uses the longitude and latitude of the place names, with the longtitude and latitude of the corners of the map to
+calculate where on the image the place is.  The convert command (part of the &lt;a href="
+http://www.imagemagick.org"&gt;ImageMagick&lt;/a&gt; suite) is used to make a copy of the map image, and then for drawing an 'x' on the
+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
+have ImageMagick installed on your server.&lt;/p&gt;
+&lt;p&gt;&lt;b&gt;Point selection on a map. &lt;/b&gt;When the user click on the map, javascript creates a URL that includes the pixels of
+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
+occurred.  This is done using a KD-tree (where the root node branches on the latitude co-ordinate, and then alternately on the longitude
+co-ordinate) to find the set of places that fall within the given rectangle in the plane.  Run-time for this is very efficient,
+theoretically O(sqrt(&lt;i&gt;n&lt;/i&gt;)+&lt;i&gt;k&lt;/i&gt;) time where &lt;i&gt;n&lt;/i&gt; is the number of points in the tree and
+&lt;i&gt;k&lt;/i&gt; is the number of points in the result.&lt;/p&gt;
+&lt;p&gt;&lt;b&gt;Javascript. &lt;/b&gt;The collection uses javascript on the content pages for the drop down box to add locations and for
+the radio buttons to change zoom.  This simply removes the need for extra buttons on the page.</displayItem>
     <displayItem name='icon' lang='en'>map.gif</displayItem>
   </displayItemList>