The GIS 20. Gina ClemmerЧитать онлайн книгу.
asking you to select a blank map template, click Blank Map (or you can click Cancel, which does the same thing). And then click OK. If this window does not appear, it is not a problem. You are simply trying to get to a new empty mapping session.
NOTE: This “Open ArcMap” set of steps is not repeated throughout this book. But you will generally use these steps to start an exercise.
WHAT FILES MAKE UP A SHAPEFILE?
After unzipping the Census Bureau files, you will have a file with the .shp extension. You will also have a few other files with different file extensions, because a shapefile is made up of multiple files, not just the .shp file.
Mandatory files:
■.shp = the visual image of the map.
■.dbf = database file, in which data is warehoused for the shapefile.
■.shx = index file, which ties the .shp and .dbf files together.
Optional files:
■.prj = projection file, which gives your map its shape, area, direction, and distance (discussed in chapter 3).
■.shp.xml = file contains metadata about your shapefile.
■.sbn and .sbx = spatial index files.
■Other files = a few other file types that can be associated with a shapefile.
Add shapefiles
1 1.Add shapefiles to ArcMap by clicking the Add Data button . You will use this tool constantly, so it might be a good idea to get to know it.
Here is the tricky part: to find your files, you must first do this other thing called “connect to folder”—and there’s a button for that.
1 2.After clicking the Add Data button, click the Connect to Folder button , and navigate to your save folder (in this example C:\GIS20). Click OK.
2 3.Select tl_2016_01_place.shp, and click Add. Then do the same thing for the county file, tl_2016_us_county.shp.
NOTE: Unless you also downloaded Alabama as your state, you will have slightly different file names. Your state’s FIPS code will replace the “01” in the file name.
1 4.If you do not see shapefiles here (they have a .shp extension), you have not properly unzipped the files or they are not in your save folder. Go back and try to unzip and add them again. If you think it’s some other issue—it’s not.
FIPS CODES
FIPS code stands for Federal Information Processing Standard code, which provides a unique ID for every parcel of land in the US. States have two-digit codes, and counties have three. So a state plus a county code is a five-digit unique identifier for every county in the US.
HOW DO I FIND MY FILES?
When you first open ArcMap and click Add Data to add shapefiles or other files to ArcMap, the C drive will not be accessible from the navigation list. This inability to get back to the C drive has led to many a frustrated beginner.
The answer is that you must first “connect to folder” to access the C drive. There are two ways to connect to folder:
1 1.Through the Add Data tool and the Connect to Folder tool .
2 2.Through ArcCatalog™ and the Connect to Folder tool , or by right-clicking Folder Connections .
Also, you do not have to choose a folder; you can simply navigate to the desktop and connect there. All connected pathways should be evident under the Folder Connections link via the Add Data tool or through ArcCatalog.
Explore essential tools
Because ArcMap provides hundreds of tools, it is essential to identify the most important ones. The tools you will use in nearly every mapping session are featured in this section. Try to become familiar with these tools and what they can do.
Go to Customize > Toolbars, and make sure the following three essential toolbars are turned on: Standard, Tools, and Draw.
The Add Data button
You already know how to add geography files, layer files, or data tables, but let’s review: simply click the Add Data button on the Standard toolbar.
1 1.Click the Add Data button and get comfortable with using the navigation list to add files, connect to folders, and generally just find your way around. You will notice if you click the little down arrow next to the button, other options appear. Ignore these other options.
The Zoom In/Zoom Out, Fixed Zoom In/Fixed Zoom Out tools
ArcGIS has four tools for zooming in and out of your map: Zoom In, Zoom Out, Fixed Zoom In, and Fixed Zoom Out.
1 2.Click the Zoom In button .
2 3.The tool works better by drawing a square around whatever you want to magnify instead of just clicking the map. For example, activate the tool, and then draw a square with it around your state. Notice how it is easier to control the image by first drawing a square. Now try the other zoom tools, and see what happens. Do not worry if you mess up your map. The next tool will help fix it.
TIP You can also easily zoom in and out of your map by using the scroll wheel or trackball on your mouse, if you have a mouse with this functionality.
The Full Extent tool
The Full Extent tool will resize your map so it fits on your screen. The tool is a great way to center—or recenter—your map.
1 4.Click the Full Extent button, and notice how your map is repositioned.
The Pan tool
The Pan tool looks like a little hand. The tool allows you to reposition the map as if you were moving it on your screen with your hand.
1 5.Click the Pan button, and move your map around. To recenter it, click Full Extent again.
Select Elements (the default pointer)
The default pointer doesn’t do anything. That’s the beauty of it.
1 6.Click the default pointer, and then click your map. Notice that nothing happens. (This tool is technically called Select Elements, which is the visible name when you hover over it. However,