Draft SO432, GIS Fall 2008

NGA Vector Data Lab

Using the VPF button on the main toolbar in MICRODEM, open the file C:\mapdata\indexed_data\vpf-shapes\VM2ALV2\NORFOLK\vpf_index.vpf.

What does the first map displayed show?  Why does the program do this, and not display the entire data set?  How does the coastline compare with the black coastline on the base map?

Display the map at "This map, full detail".  Is this map useful?  What does it say about the proper "scale" for this data set?  Get a screen display showing the scale at which this map should be displayed.

This data base consists of 10.5 MB of vector data.  This is a small sample data set; a full data set would be 10s of times larger (in the 100's of MB), with the same level of detail but covering a larger area.  What would you predict about how you could display such a larger data set?

Can you turn off layers on the map?

If you do an ID operation on a symbol on the map, what kinds of information is displayed about the records in the data base?  Are the codings human readable?   If you look at the two files "ATT_DECS.DBF" and "ATT_VAL.DBF", both in the same directory as the MICRODEM program, do they help interpreting the codings?

Open the file  C:\mapdata\indexed_data\vpf-shapes\VM2ALV2\NORFOLK\vpf_index.vpf in Excel or as a database in MICRODEM.  What is in this file?  Where is the actual map data for the VMAP?

There are files in the data set with the extensions PFT, LFT, and AFT?  Is there any meaning to these?

Find the data file(s) for the roads.  What format are they in?  How does the computer know how to draw the roads, and how many different categories are on the map?

Get the TIGER data for this area (you want Virginia Beach City), and compare the maps from the TIGER and the VMAP2.  Which is better, and why?  Insure that you consider differences that might result from the actual data, as opposed to how the GIS program handles the data.