ENVR 468 Exercise

 

You want to display some maps in MATLAB with pollutant information for the state of Louisiana after it was struck by Hurricane Katrina.  You were able to get pollutant concentrations that were sampled in the floodwaters from EPA’s website.  Unfortunately EPA did not have any GIS shapefiles containing other information about Louisiana to display on your map.  Therefore, you contacted the state directly and they provided you with files for displaying the Louisiana state border and the parish (like a county) borders. 

 

1) First create a folder for storing these files named “Louisiana

 

2) The state has provided .e00 files for the state border and parish borders which can be read into MATLAB.  Download them into the newly created Louisiana folder.

 

            Parish borders: pbpeu.e00

State border: sbgeu.e00

 

3) Start BMElib in MATLAB.  Change the current directory to …/Louisiana

 

4) Display your .e00 files (hint: type “help readarce00” or see document on creating ‘GIS_interchange_file’ to find the example on how to read these files).

 

5) Notice the axes on the two figures have very different values (or the two don’t match up if displayed in the same figure).  Obviously, the state did not use the same coordinate system when it created these files.

 

6) Luckily, you have also been given the original GIS files that were used to produce the .e00 files.  Download their respective zip files to your Louisiana folder and unzip them.

 

            Parish borders: pbps.zip

            State border: sbgs.zip 

 

7) Start ArcMap.  Select “A New Empty Map” and click “OK.”  Then click on the “Add Data” button and navigate to pbps.shp (in the newly created …/Louisiana/pbps folder).

 

8) The units for this file are unknown.  Luckily you have the information that this file’s coordinate system is NAD27 Louisiana State Plane South.  Since this projection isn’t defined on the shapefile, we need to define it.

 

9) Open ArcToolbox.  Then select:

            Data Management Tools->Projections and Transformations->Define Projection

            The input dataset is pbps.shp

Click the button beside coordinate system and then choose Select-> Projected Coordinate Systems->State Plane->NAD1927->State Plane Louisiana South

Click “OK” twice and the projection should be defined

 

10) If you open a new ArcMap document and add pbps.shp, the shapefile should show “Feet” instead of “Unknown” with the coordinates

 

11) Now you need to define the coordinate system for the sbgs.shp.  Repeat the same process as before, but define the projection as “Geographic Coordinate Systems: North American Datum 1983”

 

12) Once you have defined the projections for the two files, open a new ArcMap document and first add pbps.shp, then sbgs.shp.

 

13) Zoom into one of the land masses most affected by Katrina, the Mississippi Delta area (Red Box).  It doesn’t have to appear exactly as the one shown to the right, but make sure your zoom includes the area where the ocean meets the land and the scale is <1:50,000.

 

 

 

If the parishes are aligned with the state border, then the shapefiles are ready to be exported into .e00 files.  Print out the zoom of the Mississippi Delta to turn in.

 

Converting Shapefiles to .e00

 

1) First, one of the two shapefiles needs to be re-projected to the same coordinate system as the other file (ArcMap transforms the coordinates for you, but MATLAB cannot do this).  Suppose we want the display to be shown in Geographic NAD 83.

 

2) Open ArcToolbox then select:

            Data Management Tools->Projections and Transformations->Feature->Project

            Input dataset: pbps.shp

            Output dataset: change this to be pbgs.shp

            Ouput Coordinate System: Geographic->North American Datum 1983

            Geographic Transformation: NAD_1927_To_NAD_1983_6

            Click “OK”

 

3) Now the shapefiles must be converted to coverages and then converted to.e00.  First do this for sbgs.shp using the following steps:

            a) ArcToolbox->Conversion Tools->To Coverage->Feature Class to Coverage

            b) Input Feature Class: sbgs.shp

                Output Coverage: change the path to C:\temp\sbgc (this can be any path that      does not include spaces in the name, the process will not accept spaces)

               Choose “Decimal degrees” from the drop-down menu, Click “OK”

c) ArcToolbox->Coverage Tools->Conversion->From Coverage->Export to    Interchange File

d) Input dataset: Browse to C:\temp, click on sbgc once the click “Add”

    Output Interchange File: Change the name to C:\temp\sbge.e00 (don’t mind the red X), Click “OK”

 

Repeat this process for pbgs.shp (name the coverage pbgc and the interchange file pbge.e00)

 

4) Go back to MATLAB, change the current directory to C:\temp.  Plot the .e00 files.  They should now be in the same coordinate system and line up properly.