From: 	Hugh Blackmer
To:	Floyd, Ruth;  Stuckey, John;  van Assendelft, Dirk
Date: 	6/22/99 11:42AM
Subject: 	stable drive letter for GIS data

The following explains why I think the /gis/ folder on Miley needs a 
uniform drive letter assigned to it.

The ArcView site license should encourage lots of people to start 
thinking about making and using maps, and will also result in the 
purchase and creation of substantial numbers of digital map files 
and ancillary images. We want to store and distribute these in an 
efficient and expeditious manner, and so need to work out some 
routines.  It seems entirely appropriate to use Miley as the main 
server for GIS coverage --since it was established specifically to 
provide for image data in various forms. A /gis/ directory now contains 
a goodly amount of GIS data.

By their very nature (being large graphics files of various sorts) 
GIS images are somewhat clumsy to deal with. For example, a 
topographic quad is probably about 6MB, so it's really desirable to 
avoid having lots of copies of it taking up network space. One way 
to accomplish this is to make use of ArcView's "project" files (.apr),
which are generally quite small (10-20K) and serve as pointers to 
the large files. Thus, a 6MB geoTIFF of Sherando quad is located on 
the L: drive in /biology/gis/ (it's under the cryptic name "o37078h8.tif");
if one has Netscape configured to recognize .apr as an extension 
that launches ArcView as an application, the URL has a link which 
(a) invokes the .apr and (b) opens ArcView with the Sherando quad 
displayed --and displayed as the creator of the project saved it (e.g., 
zoomed to a particular feature).  Thus, a user may retrieve a map 
and perform various actions on it (add layers, change extents, etc.), 
and can then save the result as a NEW .apr project file, and a third 
person can then retrieve and use that derived project --all drawing 
upon the original geoTIFF image.

The problem of the moment with Miley is that it has to be mapped by 
each user individually --I have it as O:, John Blackburn has it as P:, 
and so on-- so that an .apr (which points to the location of the image 
on which the project is based) can't be shared.  The solution, clearly, 
is to have a uniform drive mapping for Miley's /gis/ directory (all 
the rest of Miley will remain off limits except for Web access). Other 
contents of the /gis/ directory, in addition to maps and images for 
general use, would include the ArcView executables  (it seems more 
sensible for people to install and run ArcView locally, rather than 
over the network, though we understand that lab machines would have 
ArcView installed as part of the standard setup) and other GIS tools 
(Microdem is a good example).  

Fairly extensive work remains to be done building web pages to support 
learners and experimenters who venture into the waters of GIS.  The 
humble beginnings are at and an image-based 
navigation scheme is in the works for locating and retrieving GIS 
data ( at the 
moment, for our holdings for the state of Virginia, though the same 
locator scheme will eventually be extended to provide access to the 
whole array of GIS data holdings). I'd like to start making .apr files to
fit with John Blackburn's work on the locator maps, but until there's a
uniform drive letter for the /gis/ folder it's not sensible to do that