Search Examples Tuesday, January 14, 2003

Previously, a user could ask Atlas to search for a 100K quad - for example, the "Bogalusa" 100K quad - and Atlas would display all maps that had a footprint equal in size and location to the Bogalusa 100K quad. The result would have been the table below.

# Name Size Vec/Ras Theme Feature Format C
Bogalusa 100K Topographic Map 9,447 K raster reference map GeoTIFF C
 

With the overlap mechanism, it is now possible for Atlas to list all maps and images that touch, overlap, contain, or are contained by the footprint of Bogalusa 100K quad. Below is table showing the first 3 and last 3 entries returned using the overlap mechanism.

# Name Size Vec/Ras Theme Feature Format C
ANGIE 24K DEM 15 K raster geophysical elevations DEM C
ANGIE 24K Topographic Map 2,753 K raster reference map GeoTIFF C
ANGIE NE CIR DOQQ 2,919 K raster reference image MrSid C
  ...
165  Washington Parish Roads TIGER1997 Files 654 K vector infrastructure roads Geomedia C
166  Washington Parish TIGER1994 Files 1,298 K vector socio-economic boundaries Shapefiles C
167  Washington Parish TM Image 2,174 K raster reference imagery GeoTIFF C

Notice that in the list of items returned by the search include a DOQQ, a 24K topographic map, a 24K DEM, and several parish files.

Also, the merging of the attribute search ability into the area search allows for the search of specific types of data including maps and images that below to particular collections. For example, it is now possible to find all DOQQ images that cover an area. Using the Bogalusa 100K example from above, the collection attribute can be set to doqq1998. With the overlap mechanism enabled, the search will return the following table.

# Name Size Vec/Ras Theme Feature Format C
ANGIE NE CIR DOQQ 2,919 K raster reference image MrSid C
ANGIE NW CIR DOQQ 2,937 K raster reference image MrSid C
ANGIE SE CIR DOQQ 2,905 K raster reference image MrSid C
  ...            
46  TYLERTOWN SE SE CIR DOQQ 3,282 K raster reference image MrSid C
47  WALDHEIM NE CIR DOQQ 3,239 K raster reference image MrSid C
48  WALDHEIM SE CIR DOQQ 3,418 K raster reference image MrSid C
 

Notice that the items returned are DOQQs.