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1 The Virginia Geospatial Extension Program GPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared by: In partnership with:

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Page 1: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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The Virginia Geospatial Extension Program

GPS Exercises

An Introductory Workshop and GIS Survival Kit

John McGee Jennifer McKee

Prepared by:

In partnership with:

Page 2: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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Page 3: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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Field Exercises: Introduction to GPS

Note that before you start these exercises, you should “delete” all data from your GPS receivers! Reference the

1. Collecting and storing WaypointsCollect and save 6 waypoints. Your waypoints should collected in an area that is easily discernable from the sky (i.e. a corner of a parking lot, a crosswalk, a point where the grass meets the pavement, right in front of a crosswalk, a small tree, etc.). We will later use satellite imagery as a “background” to view the data that you have collected, so it will be important for you to be able to identify the points where you collected your GPS data so that you can assess the accuracy of your data collection efforts! Provide your own names (i.e. tree, pole, car) for at least 3 of your waypoints.

Jot down the names and descriptions of each of the waypoints that you capture:

Waypoint #1: Waypoint #4:

Waypoint #2: Waypoint #5

Waypoint #3: Waypoint #6:

Make sure that each waypoint is saved!

2. Estimating Area and PerimeterWe are now going to us the GPS receiver to estimate information about a nearby parking lot.

a. Use your “best guess” to estimate the area of the parking lot (your estimate can be either in acres or sq. feet).

b. Use your “best guess” to estimate the perimeter of the parking lot (use either feet or yards).

c. What is the GPS calculated area measurement of the parking lot in each of the following units?

-Acres: -Hectares:

-Square feet: -Square meters:

-Square yards:

d. How did your estimate (your “guesstimate”) of the area of the parking lot compare to the GPS

Page 4: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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calcuation?

After you complete the fi eld exercises, let’s head back up to the computer lab!

Page 5: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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e. When you return to the computer lab, use ArcGIS to measure the area of the parking lot using the measure tool (supported by aerial photography). Use the “Add Data” button . Navigate to your GPS_Data_Folder, and add the following aerial photos to your table of contents.

• VT_AerialPhoto1.sid• VT_AerialPhoto2.sid• VT_AerialPhoto3.sid• VT_AerialPhoto4.sid

How does the GPS calculation (from the parking lot) compare with the GIS calculation (make sure that your comparison uses the same units)?

• GPS Area Calculation:

• GIS Area Calculation:

f. Which do you think is more accurate, the GPS calculation, or the GIS calculation?

g. Can you substantiate your answer above (why do you suspect that either the GPS or the GIS cal-culation might be more accurate? What additional information might help you to better assess the accuracy of the GIS area calculation and of the GPS area calculation)?

h. Extra Credit! Assume that we had a storm that dumps 2 inches of rain on the area during a one hour storm event. How much stormwater water runoff (in gallons) were generated by the parking lot during this 1-hour weather event? (hint: 1 cubic inch = 0.0043 gallon)

i. How could we mitigate this stormwater runoff in the future? How could we potentially use GIS and GPS to help model and mitigate the impacts of stormwater runoff? What data layers would be appropriate to support this application?

3. Saving your data with DNRGarminYou have saved the the Waypoint data that you collected “in the fi eld” (the parking lot) to your GPS receiver. Now we are going to transfer and save the Waypoint data to your computer. This process is called downloading (you are downloading the data from your GPS receiver to your computer). You will then be asked to import and view this data in ArcGIS and in other geographic software (GoogleEarth). We’ll add some additional data (aerial photography) to provide you with some con-textual (background) information that is useful to help orient the downloaded data.

Page 6: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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GPS data is best saved in a .gpx format. GPX data can be “easily consumed” by an array of products (GPS receivers from different companies) and software programs.

What is a .GPX format, you may ask?GPX is a light-weight XML data format that supports the interchange of GPS data (waypoints, routes, and tracks) between applications and Web services on the Internet. Since it is supported by XML format, it is open source! GPX formatted data is a “common denominator” for GPS data!

We will go over the processes of uploading and downloading and saving GPS data as a group. How-ever, for future reference, this information is outlined in detail in the “Introduction to DNR Garmin for Educators” handout (also available here http://www.gep.frec.vt.edu/cooltools.html ). This re-source is also available from the VCCS Geospatial Portal (http://www.vccsgis.org).

3.1 Saving WaypointsSave the Waypoints that you collected to a fi le in your working folder. You are going to save the GPS data in 2 different formats: 1.) a GPX fi le, and 2.) an ArcView (ArcGIS) Projected Shapefi le:

Here are a couple of suggested names for your fi les (just remember “where” you have saved them!:• <Your_name_Waypoints.gpx>• <Your_name_Waypoints.shp>

Figure X: Saving your GPS data as a projected shapefi le

Page 7: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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3.2 Saving Tracks (trackpoints)you will now save your GPS track data to your hard drive. You will need to save these fi les in 2 dif-ferent formats (GPX and as a projected shapefi le). Save these data in the same folder as you saved your GPS Waypoints. • <Your_name_Trax.gpx>• <Your_name_Trax.shp>

What is the difference between these two formats? When would you send someone a .shp fi le, and when would you send someone a .GPX format?

Note that these GPX fi les can be shared (emailed) with other individuals. Other users who receive the GPX fi le can then “upload” the fi le (using DNR Garmin) to their own GPS receiver! Can you think of some real world applications examples where this would be useful?

4. Integrating GPS data with ArcGISData collected by a GPS receiver can be easily integrated with a GIS. Just imagine that anyone with a smartphone or other GPS embedded device will someday be a mobile data collector! All these data will need to be “mapped”!

You will now integrate the data that you collected with your GPS receiver with ArcGIS.

a. First start (open) ArcGIS

b. You will need to add some aerial photography to add “context” to your view. If the following are-ial photographs have not already been added to your view, then you will need to add them now (from your <GPS_Data_Folder>): • VT_AerialPhoto1.sid• VT_AerialPhoto2.sid• VT_AerialPhoto3.sid• VT_AerialPhoto4.sid

Page 8: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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Figure 3: Adding aerial photographs to the Table of Contents

Now we are going to superimpose the data collected with your GPS “ontop” of the aerial photogra-phy. This will provide some context for your GPS data.

Select the “add data” button.

You will need to add the two fi les that you downloaded from your GPS and saved onto your hard drive (the projected track shapefi le and the projected waypoint shapefi le) to your ArcGIS Table of Contents.

Once your GPS data have been added to your ArcGIS Table of Contents, start zooming in and pan-ning around and examine your data.

Page 9: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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Figure XX: Integrating GPS data into ArcGIS

How accurate does your GPS data appear relative to the aerial photographs?

Are there some areas of the parking lot that appear less accurate than other areas? What may be caus-ing these errors?

5. Integrating GPS data with GoogleEarthUse DNR Garmin to and save your GPS Waypoints as a KML fi le. We will work though this as a group, but be sure to reference the last page of the “ Introduction to DNR Garmin for Educators” handbook!

Here are the steps that we will be following to integrate GPS data with GoogleEarth:

a. Make sure that GoogleEarth (http://earth.google.com) has been installed on your local computer.

b. Using DNRGarmin, save your waypoints from your GPS receiver to your hard drive as a KML fi le.

Page 10: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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c. Savey your tracks from your GPS receiver to your hard drive as a KML fi le.

d. Once you have saved your waypoints and tracks, you can double click on each of the KML fi les. GoogleEarth will launch, and “presto”, your data should become visible in GoogleEarth!

e. Note that you can email the KML fi le to anybody (or post it on your Website) if you would like to share this information to others (but remember, other users will need to be sure that GoogleEarth is installed on their computers).

6. Integrating Digital Photos with GPS Data Using the Tracklog Method

There are several methods that will allow you to effi ciently “link” digital photographs with GPS coordinates. This process is often referred to as “geotagging”. When an image (document or pho-tograph) is “geotagged” then you are able to conduct a search for documents not only based on keywords, or time/date stamps but on geographic location as well! Photos that have been geotagged essentially can be searched through a geographic library! And not only can photos be spatially searched, but they can be “displayed” in a geographic context as well.

RoboGeo is one software package that is both easy to use, and fairly inexpensive to purchase. Fur-thermore, is fairly “fl exible” as it works with multiple operating systems (XP, Vista, Windows 7).

Refer to the handout “Coordinating Photos with GPS Using RoboGeo”. This handout is available for download from the Virginia Geospatial Extension Program (http://www.gep.freq.vt.edu) under “cool tools” or via the VCCS Geospatial Portal (http://www.vccsgis.org).

7. GPS Navigation You will now use the GPS to navigate to some specifi c locaions on campus. Make sure that you save a Waypoint beside our building before you head out, so that you will be able to fi nd your way back again!

We have already collected some GPS coordinates from special places across the VT campus and haved saved these as individual Waypoints (just like you did in #2). This waypoint fi le has been saved on your computer hard drive in a GPX format (GPX is a common format specifi cally designed for GPS data that is “readable” by most GPS software programs (as well as GIS software programs, GPS receivers, and other devices).

a. Upload the GPX fi le that is located in the <GPS_Data_Folder>. The name of the fi le that you need to download to your GPS is the “Campus Scanvenger Hunt GPS Waypoints.gpx”). You will need to upload this .gpx fi le from the computer hard drive to the GPS receiver using the DNR Gar-min software (we’ll go over this as a group, by you can also reference the handout “Introduction to DNR Garmin for Educators”.

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b. Once the fi le has been uploaded to your GPS receiver, you can verify that the upload was success-ful, by going by accessing the Waypoint list on your GPS. You should see the following GPS Way-points (and corresponding coordinates) listed on your GPS receiver.

F ID---- Latitude Longitude Symbol------------- T O CommentW AC N37°13’49.92” W080°25’13.87” Waypoint I E 05-JUL-07 15:10W CB N37°13’22.82” W080°25’10.10” Waypoint I E 05-JUL-07 14:29W CG N37°13’29.96” W080°25’27.40” Waypoint I E 05-JUL-07 14:41W CS N37°13’49.68” W080°25’14.92” Waypoint I E 05-JUL-07 13:57W CT N37°13’46.16” W080°25’20.51” Waypoint I E 05-JUL-07 15:02W DF N37°13’26.56” W080°25’22.46” Waypoint I E 05-JUL-07 14:36W GZ N37°13’29.96” W080°25’44.20” Waypoint I E 05-JUL-07 14:48W LBB N37°13’29.40” W080°25’07.90” Waypoint I E 05-JUL-07 14:20W PF N37°13’34.81” W080°25’33.06” Waypoint I E 05-JUL-07 14:56W PY N37°13’43.81” W080°25’13.76” Waypoint I E 05-JUL-07 14:07W TM N37°13’47.75” W080°25’10.12” Waypoint I E 05-JUL-07 14:02W TTH N37°13’37.78” W080°25’12.80” Waypoint I E 05-JUL-07 14:13

You will now have 45 minutes to try “fi nd” as many of these GPS Waypoints as you can. Be sure to answer the questions associated with each GPS Waypoint. And again BE SURE TO COLLECT A NEW WAYPOINT NEAR CHEATHAM HALL BEFORE YOU LEAVE, SO THAT YOU CAN NAVIGATE BACK TO THE BUILDING WHEN YOU ARE FINISHED!

Also, if you are really organized, you might want to take a few minutes to identify the Waypoints that are close by.... or develop a route to help you navigate more effi ciently!

8. GeocachingGeocaching can be a recreational hobby or an obsession! However, geocaching can also be

used to support educational objectives as well. The Virginia Geocoin Adventure, developed by the Virginia Geospatial Extension Program (http://www.cnr.vt.edu/gep) in partnership with Virginia 4-H (http://www.4-h.ext.vt.edu) (and the National Geospatial Technology Extension Network (http://www.geospatialextension.org ) developed geocaching exercises and STEM-based exercises to further engage students.

If time is available, we will conduct a formal geocaching exercise using a geocoin or other trackable item!

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NOTES

Page 13: GPS Exercises - Virginia Techgep.frec.vt.edu/VCCS/materials/PDFs/2.4.1-GPS_Exercise.pdfGPS Exercises An Introductory Workshop and GIS Survival Kit John McGee Jennifer McKee Prepared

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NOTES