MICRODEM GIS Course Lab 2: Projections and Horizontal Datums

This lab will look at three things:

In looking at map distortion, we will use the Tissot indicatrix.  This is a circle on the ground, and we can look at it on the map and see what distortion occurs.  We can also look at the values for h and k, the distortion in the two directions.  For many maps, we may need to look at the 4th decimal place to see any changes.

The tools for both the datum transformation and map distortion are on the Cartography menu, and may give you several options:

Download TIGER data (2017 edges) for your home county.

You will have to pay close attention to several things for this lab to work:

You should clearly label any output files your create, and any maps.  The computer term GIGO applies: looking at datums shifts from WGS84 to NAD27 in western Europe will not reveal anything very interesting.


1.  Planar projections

Look at the following projections: stereographic, orthographic, and Lambert azimuthal equal area.  Except for the polar stereographic, these projections are only appropriate for looking at an entire hemisphere.  Make a table with your answers to the first two parts.

2.  Datum shifts

3.  Projections and UTM and MGRS Coordinates

Answer the following questions, with screen captures as appropriate.  Consider just your home county TIGER data (2017 edges):

Detailed directions:

Getting coordinates of a point.  Understand that the accuracy of the resulting coordinates depends on the dexterity of your mouse motions, and the pixel size.  On a map of the world with 10 km pixels, your coordinates are at best only accurate to within 10 km, and maybe more if you cannot click on the exact pixel you want.

Finding an address

Finding the UTM Zone. 

Zooming the map to your county

Zooming to your streeet

Last revision 8/29/2018