Draft SO432, GIS Fall 2008

NGA Data Sets Lab

We are using the MICRODEM program.  It has an extensive online help file. 

Complete the two tables and paste them into a Word Document.

Data is in "C:\mapdata\nima_data types".  Set file type to all if you do not see the files you want.

CADRG.  This is imagery (scanned maps).  Look at the 7 maps of Fort Irwin, CA in CADRG format (GNC, JNC, JOG, MIM, ONC, TLM50, and TPC).  Put them in order by scale from smallest (TOP) to largest (Bottom), and complete the table below. The imagery has 1536x1536 pixels in each file; insure that you zoom in or blow it up to see the actual level of detail.

CIB. Look at the 4 CIB frames (Fort Hood 1 m and 5 m, Fort Irwin 5 m and 10 m). Load the DT1 file for the area (DTED 1) before you load the imagery.  The imagery has 1536x1536 pixels in each file; insure that you zoom in or blow it up to see the actual level of detail.

• Locate the coverage for the larger scale image on the smaller scale image.
• What level of detail can you see at each scale?
• How does the storage requirement vary at each scale?  Compare the size of each block, and the number of blocks needed to get the same coverage.

DTED Look at the DTED Levels 0, 1, and 2 for Fort Hood, Texas (Hood.dt0 through Hood.dt2).  The Level 2 covers a smaller area than then other two to keep the download to a reasonable level.

• Look at a 3D view (oblique or perspective or OpenGL) from each data set.  How do they differ?
• These use 2 byte integers for each elevation.

GAZETTEER.  Download a country gazetteer from the NGA web site, or a state gazetteer from USGS, and convert it into a database.  Open it in MICRODEM, and discuss what it shows.  At what scale does it work best?  Insure that you try the label gazetteer features option, and see how that can be customized.