 
Exercise 16 - Digital Cartographic Databases

	Importing the DLG vector files
Run DLG (in File/Import/US Goverment Data Formats) and input BE_RD.
Chose Lines as type of data and ROADS as the output file.
Choose SCAN DATA to see the major and minor codes attributed to the various line 
data; choose (click the buttons for  Primary route (201), Sec. Route (205), Road class 3 
(209), Road class 4 (210), and Photorevised (0). Click OK to return to the previous 
menu, and change the Id's for each line type (Assign New ID box), recognized from its 
minor code in the Assign New ID box, to 1 (major roads), 2, 3, 4, and 5 (for 
photorevised), in the `Features to Extract' box. Click OK.
Run the Symbol Workshop (in Display) and assign a line type, colour, and thickness, to 
each line type, e.g. for Primary route - red, full line, thickness 3; Secondary route - 
green, broken line, thickness 2, etc, and  save as a line symbol file called `roads'.
Display ROADS with the symbol file ROADS.

Follow same procedure for BE_HYD, extracting streams (only) as lines into a vector 
file  STREAMS (attribute value of  `1'). Create a line symbol file `streams' with `1' as 
blue. Extract  marshes (attribute value `1') and lakes and ponds (attribute value `2') as 
area (polygon) features into WATERBOD, and construct an appropriate polygon 
symbol file `waterbod'.

	Importing the DEM raster files.
Run DEMIDRIS (Files/Import/US Goverment Data Formats); import BLKEAR.DEM; 
output DEM. Display with the Idrisi 256 palette, and autoscale. Check the HISTO 
distribution and then set the minimum value in the .doc file to the minimum non 
background value [218]; in this case querying the cell values will give the real elevation 
values and not the palette value [0-255]). Change the colour number 0 in the idrisi256 
pallete to white and save as a  BLKEARTH palette file. Display the  image with the new 
palette.
Layer ROADS over DEMC. The raster and vector images are not registered because 
DEMC is a NAD83 datum image and ROADS is a UTM NAD27 datum image.

Exercise 17 - Changing the Reference system with PROJECT

	Run PROJECT (in Reformat) and input STREAMS; use STREAMS83 as the 
output file name, and US83TM16 as the output reference system. Same for ROADS and 
WATERBOD.
Read page 13-105 regarding  the error characteristics of the UTM coordinate system.
FIGURES
Figure 1. Plate Tectonics.
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