Project Management & Data Dictionary Design

Discussion

After inventorying your current GIS database and determining GPS unit needs for your project, it is important to take time to implement a systematic project management strategy and finalize the feature and attribute information to be collected in the field.

Implement a project file management system before going into the field. READ MORE >>

A GPS field project may generate tens or hundreds of files over the course of a field season. Take time to set up a coherent file management scheme that organizes data transferred from the GPS to the PC and a logical sequence of file naming conventions that enable you to track file changes over time. At a minimum this will include a folder that accepts the raw un-proccessed data and another folder for edited/processed files.

Storing the GPS and GIS data for your project effectively can be done many ways. Here are some suggestions when planning the electronic data storage for your project. READ MORE >>

Example 1 - Trimble Default: Trimble's Pathfinder Office uses a "Project" method that creates three subfolders for a particular mapping project "Export, Base and Backup". You can set up project's for different groups of data. For instance, if you are a biologist, you could create a project for each park, each major biological sampling task, or each month you return to that park to sample.

Example 2 - GPS-GIS file organization: Your own system with a project folder, GPS & GIS subfolders, and additional subfolders for raw, editing, and finalized data.

After your project management strategy has been started, develop a data dictionary. The term "Data Dictionary" in this context comes from Trimble's Pathfinder Office Software terminology. On this website it refers to creating a list of features and their associated attributes to be collected in the field. Below are the steps to data dictionary design and implementation.

1. Identify the features you want to map. READ MORE >>

Make a list of all the real world physical objects to map. Categorize the list into point, line and polygon features.

2. Identify the attributes that will be recorded for each feature. READ MORE >>

Collecting standard attributes is one way of ensuring the GPS field data collectors gather information about features relevant to research needs and your park's GIS database needs. Determining the information to collect about each feature should be done in conjunction with all of the people you anticipate will need or use the data. Limit the attributes to characteristic you can observe in the field.

Determine for each attribute the following:

3. Implement the feature and attribute list with your GPS unit. READ MORE >>

Utilize your GPS unit and equipment to automate feature and attribute capture. Some examples of this are Trimble Data Dictionary files (*.ddf) or ArcPad forms. If automation is not an option, utilize the old fashion notebook and pen method to track feature and attribute capture.

4. Test your Data Dictionary Design. READ MORE >>

Trial run data collection with all of the project's data collectors before the real thing. This will help everyone understand the features and attributes to be collected. It will also help everyone become comfortable with the equipment and technology. The following is great advise from the NPS Cultural Resource's GPS Manual "You can expect to revise your attributes as work progresses. If at all possible, test your scheme under field conditions. Take it to your project site and start mapping. Look around for other features that should be in the database. Decide if additional data can be collected with minimal effort. For instance, if your project was to map an interpretive hiking trail, it will cost little additional effort to map the signs as you map the trail. A comprehensive inventory of interpretive signs can be a large undertaking, and this extra effort could give you a head start. Also test your attribute information and make sure that nothing was left out. A menu choice called 'other' is often a good idea, just in case."

Watch outs!

Multiple GPS units create a file management nightmare - GPS units create files to store data during a field session. If you have many GPS units on a project, you might consider assigning a unique identifier to each unit and making sure files downloaded for each unit contain the unique identifier within the filename. For example, with three GPS units, the unique identifiers could be A, B, and C and they could prefix the file's name.

Include Reference Features in your Data Dictionary - A very useful type of feature to include in the field is a reference feature. These provide context or serve as a check on the location of your primary features you need to map. An example of a reference feature in a trail mapping project, would include points taken at trail heads, major trail turning points and trail junctions to clearly define the route of a meandering trail. These points are very useful later in editing lines since they highlight major trail course changes and provide something to snap to when post-processing or finalizing the GIS data.

Include Generic Features in your Data Dictionary - No field data collection effort can be perfectly planned and there might be an opportunity to collect something unexpected. If the data collection software you are using does not include generic features (point, line, and polygon) automatically, then add these to your data dictionary. Be sure to have at least one free text attribute field for the data collector to describe the feature so there is less confusion back in the office.

Glossary of Terms

attribute - A characteristic of a geographic feature described by numbers, characters, and images typically stored in a tabular format & linked to the feature by a user-assigned identifier [Source: ESRI ArcDoc help]. Attributes can be referred to as non-graphic data in a GIS and each feature may have more than one. Attributes can be thought of as questions about a feature that you want answered during data collection. For example, 'Surface Type' would be the appropriate attribute for a question like, "What is the surface of the road (line feature)?" [Adapted from Source: Trimble, Classroom Manual "Pro XR/XRS with Asset Surveyor", Revision A, 1988]

free text - As an input for a database or in this case a GPS attribute, free text refers to no constraint on the value entered except for its format and length. A good example of a free text attribute might be a feature's name. In most cases a list of input chooses would be unconstrained and unimaginable.

menu -As an input for a database or in this case a GPS attribute, menu refers to a constrained list of values. A good example of a menu attribute might be a feature's type. In the case of a sign found in your project area, you might wish to have data collectors choose types such as regulatory, warning, or informational.

Links (Step-by-Step How To)

Project File Management Information and Examples: Attribute Standards, Data Dictionary Design & Support Files:

Site Suggestions. Contact ifer_mccollom@nps.gov if you have any suggestions or possible Step-by-Step How To links.