Join Adam Wilbert for an in-depth discussion in this video Working with GIS data files, part of ArcGIS Essential Training.
- Geospatial data comes in a wide variety of formats and specifications that have been developed by various countries, federal and local government agencies, and software engineers over a period of several decades. Some have gained widespread adoption, such as ESRI’s proprietary shapefile format, and some are used for very specific data products, such as the US Geological Survey's DEM, or digital elevation model, which is an open standard used around the world for sharing elevation data. While there are hundreds, if not thousands of different ways that your geospatial data might be stored, there are some very common handling procedures that you should be aware of that differ from how you might work with other files on your computer.
The first thing that you need to be aware of is the fact that a single data source might be stored in dozens of interrelated files on your computer, and each one needs to know exactly where the others are. Here, inside of our exercise files, I’m in the Chapter_00 folder. Inside of that, I’m going to go into this Chapter__00_Data file. Here, you’ll see several files that have the name Populated_Places. This is an example of an ESRI shapefile storage format. All of these files are connected and if one of the files in the group moves or is renamed, it can corrupt the entire data source. There is also this folder here called States_Provinces.gdb.
This is data stored in a geodatabase format and inside of the folder are all of the files that are required to make it work. For this reason, you should only work directly with geospatial data files inside of a program that is designed to manage these connections for you. In the ArcGIS suite, that program is called ArcCatalog, which we will take a look at later in this course. Ok, let’s go back up a couple of folders here, and the second thing you will need to be aware of is that the map documents that we will be assembling, end in a .mxd file extension, such as this one here. You’ll find them inside of the individual chapter folders.
These files store information about the presentation of your data, including layouts and colors. They don’t store any information about the actual data that you are mapping. Instead, links to the data sources that we were just looking at are stored. So once again, if something moves or gets renamed, your map document .mxd files might lose track of the data. In this case, it’s a simple matter of telling your document where the data moved to. When moving the course exercise files to your computer, it might be the case that your file path will be different than mine, and you’ll need to reconnect the map document to the data files that it references.
I’m going to go ahead and open up this Reconnect file here to show you how to do that. When I double-click on it, ArcGIS, or ArcMap loads, you’ll notice that on the left side of the screen is a listing of my data sources that are used in this particular map document. In this case, we’re just using the States_Provinces data. If you see any red explanation points, such as this one here, it means that the document has lost track of where the data should be coming from and it needs to be reconnected. To do this, simply click on the checkbox here to unselect it, and then check it on again. That’ll open up the Set Data Source window here.
From here, I’ll press the Home button, which will take me to the folder that contains the .mxd file that we’re working with, and then I’ll go into the data file for that chapter, and then find the original data source. Then I’ll select the States_Provinces geodatabase, double-click to go inside of it, and select the States_Provinces file inside. Let’s go ahead and say add to reconnect the file. Now I’ve tried to create these exercise files in such a way that you probably won’t have to deal with missing data references, but I can’t predict your specific computer setup. If you do need to reconnect the data, rest assured that you’ll only need to do it once per file.
And after saving the map document, the new file paths to the data will be stored from that point forward.
- Getting to know the ArcMap interface
- Geocoding addresses
- Measuring distances
- Adding and importing data
- Labeling and adding graphs
- Editing layer properties
- Seeing multiple views
- Making selections
- Exploring geospatial data with ArcCatalog
- Working with vector and raster data
- Styling the map
- Adding your own data
- Using the ModelBuilder
- Adding a legend and annotations