GPS handhelds are great when they work. However, they need a clear view of a large area of the sky to get a "fix". Here at HSU, and in many areas around the world, this is hard to come by either because you are in a canyon, have a lot of tree cover, need higher resolution than a GPS can provide or some combination of these factors. In these cases, we need to find other solutions to get spatial data that meets our research needs.
Scenario:
This is a group project and all data collection and analysis can be done as a group. However, the final report should be created by each student independently, including the map.
You'll need to checkout the following equipment from the stock room:
You'll need to get together with your partners and create your own protocol and data sheet for this lab. Your data sheet needs to include columns for the following anything else you might want to include.
For this lab, we're going to be doing a common exercise, mapping the location and size of trees.
The problem with a GPS is that it needs to see at least 3 satellites to obtain a "fix". When you're in a forest or canyon, you can quickly loose the ability to use your GPS. The accuracy of the GSP will also be a problem if you want to identify objects in relationship to one another such as the objects shading a stream. One method to overcome this is to establish a "station" where your GPS works and then "shoot" the location of what you are interested using a compass and then measure the distance to the location. Then, you can use a little bit of trigonometry to compute the location interest from the known point at the station.
Note: previous classes have found that the GPSes we have are actually pretty good even in tall stands of redwoods. I still feel this exercise is of value in case you have to "shoot" locations that are not accessible and to understand how most of the older datasets were collected.
We'll be heading to the entrance for the Arcata Forest and finding some trees we can survey. You can start with smaller trees but you'll want to include some that are well within the forest. You'll also want to estimate the height of your trees. There are a variety of methods for doing this and you can come up with your own or use the one described by the instructor.
Note: Streams and roads are dangerous and you must be careful! Use the range finder directly when possible. When using the leveling rod, please be careful and do not attempt capture points that put you in danger. Also, if anyone in your group is limited in their mobility, feel free to stick to measure trees just along the road or a flat path.
Download the data from the GSP as in the previous lab (I've updated the previous lab with more detail on downloading the data with northings and eastings). Import these features into ArcGIS and then create a map of the features based on the coordinates. Create a CSV (or Excel file) from your computer/range finder coordinates and import them into ArcGIS.
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