CEEn 414 - Civil Engineering Applications of GIS

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Map Projections

Purpose: Learn how to download data from various websites and use ArcView to project layers from one coordinate system to another so that they can be used together

Assignment:

In order to practice working with data in different formats and projections you will download the following data from different web sites:

  1. Background 1:24,000 digital raster graphics (DRG) file of the 1:24000 Topo Map for Provo.
  2. Land Use/Land cover for the Wasatch Front area from WebGIS.
  3. Soil polygons for Utah County from the NRCS web site.
  4. Road center lines for Utah county from the Utah County GIS web site.

Each of these data layers could be in a different projection, and may or may not have a projection defined at all.  You are to define them (as necessary) so that they can be displayed correctly overlayed in ArcView Map in the UTM NAD27 Zone 12 projection.  You will have to inspect the web site or data files yourself to determine what their native projection parameters are so that you can make sure they overlay correctly in ArcView.  

There are two basic procedures

1) You need to set the projected coordinate system in ArcMap for your Data Frame to be UTM NAD 27 Zone 12.  This is done in ArcMap under the Data Frame (Layers) Properties dialog. (Alternatively you can load as your first data layer one that you know is in UTM NAD27 Zone 12 and has its projection already defined as this will default the Data Frame coordinate system for you).

2) You need to define the projection for each dataset so that ArcMap will know how to project on the fly to UTM NAD27 Zone 12.  This is done with ArcToolBox by searching for Projections and using the Define Projectsions tool, or from ArcCatalog by right clicking on a dataset and choosing Properties.

You will also want to change the fill style for the land use and soil polygons to transparent and set their outline color to something other than black.  Bottom line is that it should be clear to the TA that all of your files display in the same projection.  On the same web page create a table that identifies the input projection parameters (datum, projection, zone, units, etc.) for each dataset.  Specific information about each of the data sets is given in the paragraphs below.

Salt Lake 1:24,000 DRG

You will get this file by going to the Utah GIS Portal.  From this web site navigate (by name) to the 1:24000 scale map images page and then find and download the Provo Quadrangle map.  It is a zip file that will have a world file in it.  Unzip the files before accessing from ArcMap or ArcCatalog.  Read carefully on this page to identify the projection it is currently defined in.

Land Use/Land Cover

You should go to the WebGIS site and download the Salt Lake City land use map.  You can pick either the UTM or Lat/Long, but be sure to define your projection according to the one you download.   The data file is zipped so you should unzip before using it.  .

Soils

The NRCS provides state-wide (statsgo) files and limited county (ssurgo) soils.  I want you to get the statsgo file for Utah for this project from the NRCS download site.  Go to the Soils Data Mart and choose to download Utah by selecting Utah and entering your email.  Poke around until you find the MetaData describing the projection parameters (it may be contained within the .prj file after downloading as well).

Utah County Data

Utah County distributes much of it's extensive GIS county data.  At a mininum download the roads (get at least the Provo extents, but go ahead and do the whole County if you want). Download some of the other data if you would like, but I recommend you not download parcels as this is a large dataset. Examine the metadata and determine the coordinate system. If you need to define the projection then do that in order to be able to add it to your map and have it displayed correctly.

Turn In

On your assignment webpage provide a brief summary of the metada (primarily the coordinate system information) for each of the four data sources (what they are originally in as they should all be displayed in the same UTM NAD27 Zone 12 system).  Then include a captured image, or linked .pdf file of your map.  Notify the TA when you are finished and give the TA the URL of your web page.