About Interactive Maps

The interactive maps developed for this site are based on digital map files available from several providers and on vector shape files we developed for the project.  The interactive maps use ESRI's ArcIMS software linking through ArcSDE to data stored on an SQL server. Metadata for files we created, and for the interactive maps, is being developed and will be posted here when completed. Digital map files were gathered from:

USGS Lake Tahoe Data Clearinghouse :   This is the foremost digital map provider for the Tahoe basin.  For our project we incorporate 10 digital map or image files, primarily to illustrate and provide points of reference on our interactive maps.  The Clearinghouse allows free download of these files from their web site. Digital maps and images we downloaded and incorporated from the Clearinghouse include:

Lakes (vector shape file)
Rivers (vector shape file)
Hypsography (contour lines) (vector shape file)
Roads (vector shape file)
Docks (vector shape file)
Buildings (vector shape file)
Soil Types (vector shape file)
Vegetation (vector shape file)
Ground Cover (raster image)
Tahoe DRG (topo) (raster image)

USGS Geographic Names Information System (GNIS) :  The GNIS identifies physical and cultural geographic features in the United States.  To identify these features on our interactive maps we downloaded the GNIS data for California and Nevada, then extracted the features included in our basic area of coverage (the Tahoe area as defined by our Website Boundary vector shape file).  The “Tahoe Places” interactive map is our primary platform for exploring this data, though it is included to a lesser extent in all of the interactive maps.

ESRI maps and Data :  Several ESRI shape files delineating basic political geography – such as Census Tract and county boundaries – were clipped to the size of our basic area of coverage (the Tahoe area as defined by our Website Boundary vector shape file).  See in particular the Census 2000 TIGER/Line Data available on the ESRI web site, converted from native TIGER format to shape files.

University Libraries :  University of Nevada, Reno, Libraries staff generated several dozen vector shapefiles and georeferenced topographical maps for the Tahoe project. The historic topographical maps were scanned by the University of Nevada, Reno library staff at 300 DPI.  The four corner points were georeferenced using latitude/longitude grids created in ArcView 3.3.  The clipped .img versions of the topos were created using an ArcMap extension.  The Website Boundary file was created using the Editor function in ArcMap.