Acquiring Local GPS Data

A. Acquire GPS Data for your Area

Your story:

By now you should have identified a layer that you would like to acquire with your GPS receiver (this will be local cultural monuments unless you have something directly for your own project you need to collect with a GPS). Again, depending on the scale and accuracy requirements of your project, the layer may or may not meet your project specifications, but it will be good practice to start using a GPS receiver and to integrate the acquired data into GIS.

1. Make sure WAAS is enabled if you have that capability on your receiver. On the Garmin eTrex units that are WAAS compatible, you can enable WAAS by going to Main Menu & Setup & System & WAAS.
2. Check the units of your receiver. On the Garmin eTrex units you can do this by going to Main Menu & Setup & Units.
3. Make sure that the Almanac is up to date by having turned your unit on and left it reading long enough to acquire the satellite data. For some units, this may take 30 minutes.
4. Check that your battery is in good condition and will last long enough to finish the task.
5. Check that the Datum is correct (default for all GPS is WGS1984). However, if you want to find something on a map, you will need to be in the same datum as the map you are working with.
6. Acquire the points you identified for your project or those of local cultural units like monuments, historic markers, or buildings. On the Garmin eTrex units, you can mark a waypoint by holding in the button (what Garmin calls the "click stick") on the front of the unit. You can change the label of the waypoint by using the click stick to highlight the label and then selecting it to enter a new name or number. Once you are done editing the waypoint, click OK with the click stick.
7. Make sure you collect the x y location, a name, a description, error, and your name and date, into a tab delimited text file.
8. For better accuracy it is better to collect a point by averaging it.
9. Make sure that your satellite geometry is good before you decide to record the way point. It needs to have a number of satellites visible in different parts of the sky and reasonably high off the horizon. The error reported by the unit may help you in assessing the quality of the reading.
10. Acquire at least ten locations. In the next section, we will bring the data into ArcMap.
11. As I said before, I always note the readings and other data in a position logging book in case I drop, lose, otherwise destroy the unit, or accidentally delete the waypoints when downloading. Often the things I record are once only events or are too far away or difficult to acquire again. I work in inhospitable areas like northern Kenya.

B. Load the GPS Data

Garmin eTrex GPS receivers are recommended for this class because they are affordable and there is an interface that can be downloaded from the Esri site or an alternative from http://www.dnr.state.mn.us/mis/gis/tools/arcview/extensions/DNRGarmin/DNRGarmin.html .

****If you aren't using a Garmin receiver, you should be able to get a table of coordinates from your receiver via a cable. You can then use the Add XY Data tool that you used in the last lesson to create spatial features from the coordinates. If you have questions about how to do this with your receiver, I will help as much as I can, but I do not know how to use all receivers.****

The following section is for Garmin eTrex receivers only.

1. Go to the Esri Support page and type gpsi in the textbox under the Search Our Site section in the upper left corner of the page and click the green Search button.
2. You will see that there is one result in the Downloads section. Click Downloads and then click GPSi (GPS Interface). Read the summary and then click the green Download button.
3. An alternative that some prefer is this download tool. The GSPi does not seem to work with all GPS units. (This is a problem as software becomes ever more integrated). http://www.dnr.state.mn.us/mis/gis/tools/arcview/extensions/DNRGarmin/DNRGarmin.html The general method remains the same if you use this interface. Other units may well come with upload software.
4. Read the disclaimer, and then if you accept, click the green accept button.
5. A File Download dialog box will pop up. Specify where you want to save the file. (I created a folder in my ArcGIS directory called downloads and created a folder within that folder called GPSi. )
6. Browse to the directory where you saved the file (AS12749.zip) and unzip the files.
7. Open the readme.txt file and follow the installation instructions.
8. Once you have completed the installation, the GPSi toolbar should appear in ArcMap.
9. Connect the GPS cable to your receiver and to your computer. Turn the GPS unit on.
10. Click GPS Interface > Waypoints > Download Waypoints.
    

    In the summary of the utility, there is a note about Error 429. If you experience this error, you need to download the Mscomm32.ocx file. You then need to register the file. This can be done by clicking the Start menu and choosing Run. Type regsvr32 and then the path where you downloaded the file in the text box and click OK.

    e.g. regsvr32 D:\Geog_488\Project_7_8\mscomm32.ocx

11. Select the waypoints you want to download. You can click the All or None buttons to make the selection of waypoints easier.
12. Click Save. Save the waypoints as a shapefile to your Lesson 7_8 directory and add the layer to ArcMap. Do the points line up with your other data layers?
13. Create metadata for your newly acquired layer.
14. Check your data to see all fields were downloaded. A number of programs drop some fields; the most egregious is the elevation field. If it is dropped and you will want it for your final project, you will need to add it manually.

C. Explore Geocaching (Optional recreational activity but good practice with the GPS)

What is geocaching?

1. Go to the Geocaching [http://www.geocaching.com/] site and find out.
2. You can locate the nearest geocaches by entering your zip code. My zip code (16801) has 91 geocaches and I've visited four of them.
3. Pick a geocache near you and at the very least post a few details about it in your write-up for this week. If you feel adventurous, visit one of the geocaches and take a little something and leave a little something.

D. GPS a Confluence (really optional)

1. Go to the Degree Confluence Module [http://www.confluence.org/] site.
2. If you are in the U.S. (lower 48) it is unlikely that you have an unvisited confluence near you, but you may still have fun visiting and acquiring your location. Browse around the site and take a look at the pictures of the confluence nearest you.
3. Pick a confluence that has yet to be documented that you would like to visit. I think I'll go and take a picture of 13°S 30°E.

E. Deliverables

This module is One week in length. Please refer to the course Calendar tab in ANGEL for the due date.

1. Readings:

Required:

• "Recreational Versus Professional GPS: What's the Difference?"
  Article from ArcUser discussing some of the things to consider when deciding what grade of GPS receiver you need.
• Trimble GPS Tutorial
  Trimble offers a basic walk-through GPS tutorial that doesn't focus on their brand.
• Texas DOT GPS Manual
  A comprehensive manual for GPS surveyors and a good example of the level of documentation used in the field -- First, skim this weighty document but read the sections on accuracy completely, if you have time read as much as you can.
• Cell Phones as new mass data collection technologies from Nature.

Recommended:

• GPS Guide for Beginners
  Garmin offers a fairly in-depth guide to GPS.
• "ARCPAD: Mobile GPS"
  An ESRI white paper about ArcPad.
• "The National Map Corps: Volunteer for a Changing World."
  The only requirements needed to contribute to this effort include owning a GPS receiver and having Internet access.
• Fun Thing To Do: Listen to a BBC World Service Podcast on Spatial & GPS Technologies (Click Here to Listen).

2. Post a project write-up including:

• discussion about what grade of receiver would be necessary to acquire data for your project (if the unit you are using is adequate for the data you are collecting, what additional layers might call for a different grade?);

3. Send the point layer shapefile for the cultural monuments you have collected including metadata.
           If you are collecting data for your project then send a point layer shapefile for that data instead.
           This should be sent to the Lesson Seven Cultural Points Drop Box as a Layer Package.
            Layer packages can be made from the tool in the Data Management Toolbox (to see  an example click here).

4. Discuss the weekly topics on the discussion forum.

5. Frustration Revisited. Having got so far, now the final project might look pretty uncoordinated. Do not become disheartened by this, as this is normal. As you begin to write it up it will all fall together. Remember that in Problem Based Learning the process is more important than the product. If you need to change course, project expected deliverables, or want to modify what you had planned, do not worry. I will take this into account at this point, too. Remember to document all your efforts and keep me informed. Contact me directly if you feel the need to discuss your plans in person. Sometimes a few words are worth a ton of emails

That's it for Part II and Lesson 7!

You have just completed module 7.

Don't forget...if you have any questions, feel free to post them to the Lesson 7 Discussion Forum.