# [GPS -- To -- GIS Workshop]{.underline}

**Joseph J. Kerski -- USGS -- <jjkerski@usgs.gov> 303-202-4315**

# Workshop Outline: 

# 

# Introduction

# Goals of Workshop

# Why GPS?

# Why GPS with GIS?

# Issues: GPS setup; coordinate systems; datums

# Field Collection of coordinates and observations/measurements

# Method A: Create text file, add table, add event theme, convert to shapefile

# Method B: Create Excel spreadsheet, save as dbf, add table, add event theme, convert to shapefile

# Method C: Automated: Collect waypoints, use NRCS GPS Garmin extension

# Coordinate Systems and Datums

# Thematic Mapping

# Collecting Base Data: DOQs and DRGs from Terraserver.

Arc8 Notes

Next Steps

# 

# Ideas and Procedures for GPS Introduction and Use in the Classroom

1\] Begin GPS discussion with a base of familiar objects and concepts:
Ask the students, \"if I were to tell you that I was 10 feet from the
far wall in the room, where could I be?\" The answer is anywhere on a
straight line that is 10 feet from the wall. Next, \"if I were 10 feet
from this wall and 5 feet from this wall, now where could I be?\" The
answer is a single point, at the intersection of the 2 lines. Next, \"if
I were 10 feet from \[Maria\]\" - answer - circle with a radius of 10
feet, from Maria. Next, \"if I were 10 feet from \[Maria\] and I could
be floating in space?\" Answer: a sphere with a radius of 10 feet,
centered on Maria. If they understand THAT, then it is not a big leap to
the following: We can determine that we are 11,002 miles from GPS
satellite A, 10,887 miles from satellite B, and so on. The intersection
of all those spheres is our current location.

2\] Base the discussion on mathematics. GPS is one of the best
real-world examples of how distance=rate \* time works. The time is the
critical component, that\'s why GPS was made possible by accurate time
pieces, since the time from the satellite to the receiver is miniscule
and needed to be accurately measured. The rate is the speed of light. So
the distance is computed by the time diff between the receiver and the
satellite. I would print some of the pages from
http://www.howstuffworks.com/gps1.htm or the Geographer\'s Craft pages
at http://www.Colorado.edu/geography/gcraft/notes/gps/gps_f.html to aid
your discussion and diagrams.

3\] Use GPS coordinates to help explain the lat-long and the UTM
coordinates on any USGS topographic map of the area you\'re collecting
the points in. Walk with the GPS and pose questions such as, \"why do
the northings on UTM decrease as you\'re walking south?\"

4\] Have students, in teams, determine the location of the school
grounds \[or wherever you\'re collecting\] on a USGS 24K topo map, via
manual interpolation, in both lat-long and UTM. Then collect
coordinates. Which team was closest? What about vertical elev? Don\'t be
too hasty on dropping the manual interpolation for the GPS reading, esp.
on the vertical.

5\] Discuss the vertical and horizontal datums in conjunction with GPS.

6\] Import the GPS coordinates into a geographic information system
(GIS). Overlay the points on a digital orthophoto of the area or a
scanned digital raster graphic (topographic map). Then you can hotlink
ground photos to the GPS coordinates. There are 3 methods to bring your
GPS coordinates into ArcView:

1\. Collect points, write them down, and manually enter via a text
editor.

2\. Collect points, write them down, manually enter them into Excel, and
bring into ArcView.

3 Collect points, store inside GPS unit, and with cable, do an upload
into computer.

Method 1:

Collect points and attributes. In text editor, line 1 should be the
header line, such as \"lat, long, pH, groundcover, O2, etc\". Line 2
begins your data, separated by commas, such as \"site1, 39.7022,
-107.4832, 5.7, grassland, 38\" Save as Text such as \"gps.txt\". Access
ArcView, Tables. Add, Add your table gps.txt as comma-delimited TXT.
View. Add event theme. Bring in your table as a point theme. Click on
theme to make visible. Change legend to make graduated symbol map based
on attributes you collected.

Method 2:

Collect points and attributes. In Excel, row 1 should be the header
line, such as \"lat, long, pH, groundcover, O2, etc\". Row 2 begins your
data, such as \"site1, 39.7022, -107.4832, 5.7, grassland, 38\" Save as
DBF such as \"gps.dbf\". Access ArcView, Tables. Add, Add your table
gps.dbf as Dbase file. View. Add event theme. Bring in your table as a
point theme. Click on theme to make visible. Change legend to make
graduated symbol map based on attributes you collected.

Method 3:

Collect points, store inside GPS unit, upload via cable into computer.
This method varies depending on the type of GPS hardware you own. The
following procedures work with a Garmin GPS XL12 receiver.

Why use method 3 with students vs manually collecting points and and
entering them into a text file? To (1)

reduce error in transcription and recording; and (2) to expedite the
process, particularly if you students are collecting many points.

1\. Clear previous waypoints on GPS unit. Make sure interface says
Garmin to Garmin.

2\. Use mark and save on GPS unit at each new point collected.

3\. On PC: Load Waypoint software. Free from
www.tapr.org/\~kh2z/Waypoint

4\. Run Waypoint.exe. Set datum and configuration.

GPS\--\> Download from GPS\--\> Waypoint.

File\--\> Save \--\> Waypoints \--\> gps.txt (or any file name)
comma-delimited

5\. Download NRCS extension:
www.ne.nrcs.usda.gov/www-nri/other/gpis.html

NEW SITE FOR EXTENSION:
http://www.ne.nrcs.usda.gov/techresources/www-nri/other/gpis.html

Move extension to extensions folder. This should be
c:\\esri\\avgis30\\arcview\\ext32

6\. Run NRCS extension. GPS\--\> AV. Append? No. Select GPS file
gps.txt.

Output shape file: Point (could use line or poly, too).

Notes: I collected in NAD 27 and placed the points on top of a USGS DRG
in NAD 27. Why were the points

all shifted to the west of where they should be? I thought initially
that I was wrong about the datum of the DRGs I was using, but most of
the DRGs are indeed in NAD 27 unless they're from terraserver.

Here is what apparently caused it: In the Waypoint software itself,
there is a setting where the user must explicitly choose NAD 27. If you
don\'t select this, it apparently shifts the coordinates to NAD 83, even
though those I was training collected in NAD 27 on the GPS unit! So,
make sure you check this if you\'re automatically uploading using
WayPoint in the future. When I did this, the points plotted right where
they were supposed to.

Also -- There IS a setting in Waypoint that allows the points to be
brought in as UTM, rather than importing them in as Lat-Long. This will
allow you to view the points table (or lines or polygons if you choose
to bring them in as such) as UTM, negating the need to change the view
properties to UTM in ArcView.

General Coordinate System Notes:

Either collect in latitude/longitude or UTM. If lat/long, and if you use
a USGS DRG or DOQ, you must change the VIEW properties in order to view
these correctly on top of the base layers. If you collect in UTM, no
view properties setting is required.

7\] You could go on a geocaching expedition!
[www.geocaching.com](http://www.geocaching.com/). Find a point, hide
something at that spot, and ask your students to find the exact spot and
the hidden objects.

8\] Examine www.confluence.org - fascinating! Site where people take
photographs of the intersection of each degree of longitude and
latitude. Show students maps of world population, vegetation, land use.
Then look at a particular site on confluence.org. What is the land use
and human impact that you find in this area? Did it match your
expectations? Why or why not?

9\] Use some USGS Landsat data or digital orthophotos from
www.terraserver.microsoft.com and illustrate how accurate the GPS is
based on the aerial.

10\] GPS in Education Point of Contact:

Anton Ninno, Systems Consultant Center for Learning Technologies

Voice: 315-431-8407 CNYRIC, OCM-BOCES

Email: aninno@cnyric.org 6820 Thompson Rd.

Web: http://www.ocm.cnyric.org/learntech/ Syracuse, NY 13221

11\] GPS & GIS Books & Videos for Educators

Integrating GIS and the Global Positioning System. Karen Streede-Terry.
ESRI Press.

Comprehensive Guide to Land Navigation with GPS, 3rd Edition with CD-ROM

Noel J. Hotchkiss ISBN 1-892688-00-X \$24.95

All About GPS: Sherlock Holmes' Guide to the Global Positioning System

Jerry Huang ISBN 957-97389-7-1 \$13.00

GPS Land Navigation Michael Ferguson ISBN 0-9652202-5-7 \$19.95

GPS Made Simple Lawrence Letham ISBN 0-89886-592-1 \$14.95

Using GPS Bruce Grubbs ISBN 1-56044-821-0 \$6.95

Using GPS with Maps (video) ISBN 0-9663800-0-2 \$20

12\) For base map images of USGS topographic maps and aerial photographs
to place behind your GPS collected coordinates in a GIS:

\(1\) Visit
[www.terraserver.microsoft.com](http://www.terraserver.microsoft.com/).
Type in a specific place and press "Go."

![](media/image1.jpeg){width="2.1194444444444445in"
height="2.5541666666666667in"}

(2). First, select a TOPOGRAPHIC MAP of the area you are interested in.
Continue zooming and panning until the area you want is in the view.
Make the image size LARGE using the button above the map. You can zoom
in until the zoom factor is 2 meters.

![](media/image2.jpeg){width="2.25in" height="1.6847222222222222in"}

(3). Select DOWNLOAD in the upper right hand corner of the image. Click
on the FREE DOWNLOAD arrow to redraw the image.

![](media/image3.jpeg){width="2.261111111111111in"
height="2.7284722222222224in"} (4) After the image has redrawn,
right-click on the image and SAVE AS \<filename_drg\>.jpg

For example, oakcliff_drg.jpg

\(5\) Click on the WORLD FILE link to open the registration file for the
image in the browser window.

Go to FILE ---\> SAVE AS \<filename\>.jgw For example, oakcliff_drg.jgw

Be sure to save this as a TEXT file, not HTML. Also, it must have the
same base name as your JPG file, above.

(6). Go back to the browser window where your topographic map is (before
you downloaded it). Click on IMAGE to see a DOQ of that same area.
(Note---Only 85% of the country has images on Terraserver at present).
The procedures for the DOQ are similar to that for the DRGs that you
followed above. Make sure the image is LARGE.

(7). Select DOWNLOAD in the upper right hand corner of the image. You
will see a screen similar to that below. Click on the FREE DOWNLOAD
arrow to redraw the image.

(8). After the image has redrawn, right-click on the image and SAVE AS
\<filename_doq\>.jpg

For example, oakcliff_doq.jpg.

\(9\) Click on the WORLD FILE link to open the registration file for the
image in the browser window. Go to FILE ---\> SAVE AS \<filename\>.jgw.
Be sure to save this as a TEXT file, not HTML.

For example, oakcliff_doq.jgw Also, it must have the same base name as
your JPG file, above.

(10). In ArcView, turn on the JPG reader extension and add your images
as IMAGE THEMES.

If they do not appear, be sure to check your file names on your system.

\*\*\* End of GPS to GIS Handout \*\*\*