This project introduces three commonly used techniques for adding spatial data to a GIS: 1) adding X, Y coordinates from a table, 2) "heads-up" digitizing, and 3) Global Positioning Systems (GPS). The purpose of this project is to familiarize you with these important methods for acquiring spatial data and some of the "challenges" associated with each. Because you will be gathering data from different sources, it is also appropriate to expand your ability to project spatial data in ArcMap. Please note, you will encounter many warnings indicating that spatial reference information does not exist for the layers you are trying to add. Don't worry, you will be creating this reference information as you go, it is part of what you should be learning in this project. Periodically examine the contents of C:\TEMP\ and note any new files that have been created that might contain this spatial reference information.
The goal of this project is to get data from various sources and in various projections processed in such a way that they all line up on your map properly. In order to do this, you must "tell" the software what projection/coordinate system your data is in. In shapefiles, projection information is stored in a file with the extension .prj. If you don't have a file like this with your shapefile (e.g. roads.prj or freeway.prj) you need to create it by "Defining" the projection. You will do this several times throughout this exercise.
Helpful excitement reducer: If you define your projection incorrectly, the easiest way to fix it is to delete the .prj file and start over defining your projection.
Make certain you have a copy of each of these class handouts:
In this exercise, you will be creating new data layers. You will need a means of saving your new data (e.g. USB drive, cloud, etc).
The following 4 sections can be completed in any order (though some excitement is possible). However, performing each section in a separate ArcMap document (.mxd) or data frame is highly recommended.
Heads-up Digitizing
In this section you will create a line layer of the roads surrounding CSUF
Follow the instructions on the handout entitled "Introduction to Heads-up Digitizing"
Section 2
Adding X, Y coordinates from a table
In this section you will create a point layer of the locations of several buildings on the CSUF campus.
Follow the instructions in the handout entitled "Adding X, Y coordinates from a table" to complete this section.
Section 3
GPS Data
In this section you will use a GPS receiver/data logger to create a point layer of selected landmarks around CSUF
See the handout entitled "Using the GPS" for details
Did you define the projection for this shapefile? If not, complete the Using the GPS instructions before proceeding.
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When you are back from "the field" and have successfully downloaded your data, continue with the remainder of this section.
Projecting Your Latitude-Longitude Data
Since you will be managing data in two different coordinate systems and projections (unprojected latitude-longitude and UTM Zone 11 in this case), the simplest technique for getting all of your data into the same coordinate system is to convert your latitude-longitude data to UTM-11, which is the coordinate system of the aerial photograph used for the heads-up digitizing section of this project.
Follow these steps to convert your unprojected GPS data into UTM-11 (Note: this is a different process than described elsewhere in this project):
Yes, the GPS units can be set to record your landmarks in UTM coordinates, but that would take the fun out of it, wouldn't it?
Section 4
(Re)Projecting already projected data
Instead of digitizing the building footprints on campus, let's use an already existing dataset. These building polygons were exported from CAD. Although they were created using State Plane coordinates, projection information was not included when the data was exported.
The data is already projected in California State Plane NAD83 Zone 6 units (feet), but the software does not know this because projection information was not included in the shapefile when it was exported from CAD. In order for ArcMap to interpret the coordinates in the correct projection, we need to run a tool called define projection.
Ultimately, we need the data to be (re)projected into UTM Zone 11 NAD83 units to match the rest of our data. Unfortunately, this is not as straightforward as changing the Data Frame Properties, but it is still rather simple. For this task we will employ another tool from the ArcToolbox. Before you can (re)project data, the current projection must be defined. Let's do that now:
Now enter the information about the existing coordinate system (this is where accurate and complete metadata comes in handy).
This procedure should have created the file Csufbldg_sp6_83.prj in the c:\temp\ directory. The .prj file contains projection information for this shapefile. Open it, if you like, and take a look.
| An interesting item: Layers that have spatial reference information (in this case, the .prj file) can be projected "on the fly" into data frames that have their coordinate systems defined. This is useful in many instances. Give it a try. This is also accounts for why "Unknown Units" still appears in the lower right. |
Now we are ready to reproject the data into a different coordinate system:
The newly reprojected layer has been added to C:\TEMP
Add it to your data frame if necessary. Unless you have set the coordinate system properties for this data frame, the layers won't line up. Take a look.
You have now reprojected the coordinates for the building outlines from California State Plane Zone 6 to UTM Zone 11. Now add the UTM version of the building outlines to the data frame containing the airphoto of campus with the data frame properties set to UTM Zone 11. How well do the outlines line up with the photo? Any ideas why they don't seem perfect?
Although you have had a chance to project and reproject data, it is possible that you are not completely comfortable with the concept of projections and the possible ramifications. Therefore you are strongly encouraged to complete this exercise as well.
Create a Geodatabase and Make a Map
Follow the steps in the Intro to Geodatabases handout. Once you have completed your geodatabase:
Zip it and email it to jcarroll@fullerton.edu (Note: Do NOT submit your geodatabase until ALL sections are completed)
Make a Map
Nothing fancy here, once you have completed the 4 sections above, simply print a map (black and white or color) that shows your digitized roads, your GPS landmarks, the point locations of the buildings with their names, and the reprojected building outlines. You can superimpose your data over the digital ortho quad if you like. You may print a hard copy of your map or upload a PDF of your map via Canvas.
Last modified 10/26/2021