Chapter 03 - Pathfinder Office Part One

Pathfinder Office is the program often distributed by Trimble when someone purchases new hardware (receivers). It is a small and efficient program for handling the data you collect in the field. Of course, it will do for looking at your data, and even manipulating it to a small degree, but to get full use out of your data, you will probably need to export it to a format for use in a GIS environment. This chapter will explain the preliminary steps to setting up a project, the office work that needs to take place before we can get out into the field and start taking measurements.

The following offers a brief overview of the steps we have to go through to complete any project that uses GPS. Step 1 will be the focus of this chapter.

1. Mission Planning - involves creating a data dictionary, checking satellite availability, checking on base station (if necessary) and configuring the receiver (explored in subsequent chapters).

The first step, before even sitting down to start your data dictionary (this will be explained in a moment) is to learn about your selected area, the geographic location(s) where you will be taking measurements. Here is a quick list of what should happen:

1. Collecting previous map data on the site, would a street or tourist map help you visualize your project, or maybe a topographic map would help better.

4. Are you close to a base station? (if you are working in New Zealand, the answer is yes)

Okay, now that you have a good idea of where you are going and what you want to measure, its time to start up Pathfinder Office and begin!

Start PathFinder Office, most likely found by selecting Start:Programs:Path Office 2.90(or any version number):Pathfinder Office. The start up screen will appear, asking for you to select project. Select okay. Often, the Map window will be open, GPS data being worked with would show up in this widow, you can exit from this window now as we will not be using it for this chapter.

Next, we will explore the function that we use to complete the mission planning step of a GPS project as outlined above.

First, here is a quick guide to some of the more useful functions of Pathfinder Office

· Data Transfer - this is the utility that we use to get files from the data loggers (the units connected to the GPS receivers that record the measurements, these will be explored in greater detail later)

· Differential Correction - this is the utility we use to compare base station and rover files to increase the accuracy of our data.

· Export Files - to convert GPS data into different formats for use with other programs, such as GIS software.

· Combine Files - use this utility if you ever need to combine files, for instance, if you visited a site more than once and used different files to collect measuremens.

· Data Dictionary Editor - this is the utility we use to create different classes for the measurements we will take in the field.

· Quick Plan Utility - this utility is designed to help us plan optimum times for taking measurements.

Okay, now that we have a basic idea of what buttons do what in Pathfinder Office, we can start to build the data dictionary.

A Data Dictionary is a way for us to catalog each type of measurement that we take in the field, GPS files record three different types of features (those features to be mapped, such as roads, building, boundaries, etc.). These types are point, line and polygon features, and they are pretty straightforward. Examples of a point feature include trees and signs. Examples of a line feature would be a road or path. Polygon features take up area, and examples include a building outline. Point and Line features have no area, they are simply markers of geographic position. When to use one of the features depends largely on what you are wanting to show in your data, is a line specific enough to show a road, or do you want to know exactly how wide that road is, and so on.

Okay, let’s start defining our Data Dictionary! Select the Data Dictionary button and you will see a screen like this:

You can see that the Name field is blank, go ahead and fill that in first, anything is fine, but it should reflect your project to some degree, and keeping it short is a good idea as some of the data loggers that we use to take measurements don’t like long names. The comment field is not required, but feel free to use it if you had to use a Name that doesn’t truly reflect your project or you plan on sharing Data Dictionaries with other people.

Remember how it was suggested that we spend some time getting to know the area we are going to map, well this is where that becomes important. First, what do you want your data to show, presumably we will be using this data to create some sort of picture. So, we have to decide what features on the landscape we need to take measurements of. For instance, if we are mapping plants along a highway or inside a park, we might need a tree feature, a shrub feature, and a grass feature. In fact, let’s build a Data Dictionary with these features. We will design a Data Dictionary for a project where we have been asked to record the vegetation along a stretch of road, the distance and location of the road aren’t important for this exercise.

The first step is to select the New Feature button, this will open a new box and we can start to input our feature. Type “Tree” into the name field of the new window, we choose Point as the Feature Classification because we can show trees as points on our map, then select okay. Don’t worry about any of the other settings, especially the default settings, that’s why they’re called default settings!

Now we need to define the attributes of the Tree Feature, we do this because we know that every tree isn’t the same (we know this because we took the time to learn about the area previously). Okay, we’ll say that our project is for the Department of Convservation, and they want to know what type of trees are along this road. First, we select the “Tree” feature that we just defined and select New Attribute to the right, like this

This will open another window, and we can begin defining attributes to distinguish between our different types of trees. We have a choice of what type of attribute to use, they are:

2. Numeric - to attach an integer value to the Feature, if we had a list of tree types with corresponding numbers, we might use this

3. Text - if we just wanted to write down a description, we can also set the number of characters

For our purposes, we will select Menu, this opens a new window with an Attribute Title Field, where we can enter Type (for type of tree, this is most probably species), and then select new which brings up the New Attribute Value - Menu Item window. In the Attribute Value, we can enter “Type 1” and select Add. This will add the Type 1 to the New Menu Attribute window and the New Attribute Value - Menu Item window will remain open. Add two more, Type 2 and Type 3, and select close to stop adding new types. At the New Menu Attribute window, select okay, and at the New Attribute Type, select Okay.

Okay, finally, just to round out our Data Dictionary, we need to define a line feature for the road. We could define this as a polygon, but we will go ahead and define it as two lines in case this data is ever combined with future measurements. We can go ahead and create this feature like the last three, define it as a line, and give it two attributes based on which side of the road the line represents, north or south.

That’s it, we have just created a Data Dictionary, this is a simple dictionary, but the skills for creating dictionaries of any complexity are the same, and we now have those skills. All you need to do now is save the file, go to File:Save and select a destination and filename, or simply select the save button shown below.

IMPORTANT! - Do not take the construction of your Data Dictionary lightly, put enough thought into it so that you don’t have to re-define any features or attributes at a later date. If you do have to there may be problems with exporting your data into other formats (some versions of Pathfinder Office won’t export to some formats if the measurements use different Data Dictionaries).

Also, some disciplines have national or international Data Dictionaries that are standard when collecting spatial measurements. Geology and Cartography are excellent examples, and many other disciplines are working in each country to develop national Data Dictionaries (Archaeology is an excellent example in New Zealand, where work has already begun on this). Basically, any discipline that uses spatial data has a need for a standard Data Dictionary so that people can use one another’s data to do comparisons without having to redefine heaps of data fields.

The Quick Plan Utility lets us take greater advantage of the GPS system by coordinating the times we are in the field. However, to use this utility, you need to have already taken a GPS receiver into the field and recorded a type of file called an “Almanac.” GPS receivers automatically record almanacs once they have locked onto satellites and can accurately begin registering measurements.

Since we need a working knowledge of how the GPS receivers work before we can take advantage of this utility, we will cover the use of it in the following chapter. If you already have an Almanac file, and you want to use this utility now, please refer to page ## in Chapter 4 to learn how.