County Maps Lab


Lab objectives


You already have the TIGER Edges file from the last lab.  From that File's Metadata you can get the bounding box for the county, which will help you in selecting data.  You should err on the side of getting too much data, rather than too little, since you can select a smaller map area in the GIS.  For the NLCD you must put a buffer on the region you select because of its conical projection,  or you will miss part of the county.  The NLCD files are small, and skimping on the area you want is a false economy, unless you want to redo the analysis.


You are likely to need GDAL; this would be a good time to download and install it. 


Get the following data sets for your county, and unzip them.  Data organization will be important.  You should make a directory for this lab, and subdirectories for each of the data sets. Save the data files for this lab, because we will be using them for the next lab.  If you have trouble recognizing what each data set is, you should look in the Metadata.

Most operations on a DEM or grid are not saved unless you explicitly do so.  The DEM is stored in memory for fast access.  In contrast, most changes to vector data happen as soon as you request them, except for filters.  If you are concerned about losing data, make copies.  The vector data sets are much smaller than the rasters we are using in this lab.


Saving files.  Give the files meaningful names, and put them in a directory where you can easily find them.


Map gallery for lab.  Look at  this to understand why we will go through a number of processing steps with the data. This lab will create a large number of data files. 

Steps to follow:

Limit maps to just the county area.

Statistics on the NLCD land cover

Difference in the NLCD between two time periods

Load Gazetteer

Use gazetteer to create a buffer on the map:

Optional enhancements

Useful Tips

last revision 9/13/2018