Sunday, March 29, 2009
Friday, March 20, 2009
GPS in ArcMap
The global positioning system (GPS) is a set of satellites and ground stations. A GPS device calculates its location using signals received from the satellites. Funded and supported by the United States government, GPS has widespread use for both military and civilian applications.
An overview of ArcMap GPS Support
ArcMap GPS Support takes as input a feed from a GPS receiver and displays the current location on the screen. You can also store locations from the GPS receiver in a log for archival or real-time digitizing purposes (see Writing GPS locations to a log). You can answer the question “Where am I?” by accessing ArcMap GPS Support through the GPS toolbar in ArcMap (see Adding the GPS toolbar) or by writing a custom application using ArcObjects.
The location is displayed as a user-defined marker symbol. You can have the angle of the marker symbol reflect the direction of motion (bearing), the size based upon the current speed of travel, and the color based upon the altitude. Previous locations can be displayed as a trail of markers or as a line that you can also customize. The trail of previous positions can reflect changes in bearing, speed, and altitude. See Changing the display options for more information.
You can keep the location visible on the screen by panning as needed or have the display pan automatically (see Keeping the current location in the view). For applications like in-car navigation and routing systems, you can snap the location to specified features, such as a street centerline. You can store locations to a log file either in streaming mode (at a specified rate or distance apart) or one at a time. When a log file is specified, you have the option of choosing which columns are added to the output feature class.
Tasks you can perform with ArcMap GPS Support
You can perform the following tasks with ArcMap GPS Support.
Show the location on the screen
You can connect a GPS receiver to a communication port on a computer running ArcMap and see the current location on the map display (see Connecting to a GPS device). You can also open the GPS Position window, which shows updated information in real time.
Digitize features
By setting up a log file, you can create a new feature class in which to store GPS locations. Once the log is defined, you can use the Stamp Current Position to Log button on the GPS toolbar to record individual points. If you'd rather automatically record locations to the log, set up the filter options on the Log Setup dialog box and click the Start Streaming to Log button on the GPS toolbar.
Snap positions to features
Consider the following scenario:
You want to have the current location snapped to the features in a feature class. In this example, you are streaming features to a log file as you drive down a road, and you want the locations to coincide with the street centerlines. You set up the connection and position display information. You then use the Snapping tab of the Display Options dialog box to choose the Roads layer (which contains street centerlines) from a list of features on a map. Next, you specify a snapping tolerance. All positions within the specified tolerance will now be snapped to the features in the Roads layer. Learn more about snapping to existing features
Replay collected information later
You can use the Simulate a GPS connection option to review data that was collected earlier and saved to a log. First, set up the simulation by choosing the log you want and set a display interval. Then open the connection to display the locations from the log on the map. You can use any point or line feature class for the simulation data.
An overview of ArcMap GPS Support
ArcMap GPS Support takes as input a feed from a GPS receiver and displays the current location on the screen. You can also store locations from the GPS receiver in a log for archival or real-time digitizing purposes (see Writing GPS locations to a log). You can answer the question “Where am I?” by accessing ArcMap GPS Support through the GPS toolbar in ArcMap (see Adding the GPS toolbar) or by writing a custom application using ArcObjects.
The location is displayed as a user-defined marker symbol. You can have the angle of the marker symbol reflect the direction of motion (bearing), the size based upon the current speed of travel, and the color based upon the altitude. Previous locations can be displayed as a trail of markers or as a line that you can also customize. The trail of previous positions can reflect changes in bearing, speed, and altitude. See Changing the display options for more information.
You can keep the location visible on the screen by panning as needed or have the display pan automatically (see Keeping the current location in the view). For applications like in-car navigation and routing systems, you can snap the location to specified features, such as a street centerline. You can store locations to a log file either in streaming mode (at a specified rate or distance apart) or one at a time. When a log file is specified, you have the option of choosing which columns are added to the output feature class.
Tasks you can perform with ArcMap GPS Support
You can perform the following tasks with ArcMap GPS Support.
Show the location on the screen
You can connect a GPS receiver to a communication port on a computer running ArcMap and see the current location on the map display (see Connecting to a GPS device). You can also open the GPS Position window, which shows updated information in real time.
Digitize features
By setting up a log file, you can create a new feature class in which to store GPS locations. Once the log is defined, you can use the Stamp Current Position to Log button on the GPS toolbar to record individual points. If you'd rather automatically record locations to the log, set up the filter options on the Log Setup dialog box and click the Start Streaming to Log button on the GPS toolbar.
Snap positions to features
Consider the following scenario:
You want to have the current location snapped to the features in a feature class. In this example, you are streaming features to a log file as you drive down a road, and you want the locations to coincide with the street centerlines. You set up the connection and position display information. You then use the Snapping tab of the Display Options dialog box to choose the Roads layer (which contains street centerlines) from a list of features on a map. Next, you specify a snapping tolerance. All positions within the specified tolerance will now be snapped to the features in the Roads layer. Learn more about snapping to existing features
Replay collected information later
You can use the Simulate a GPS connection option to review data that was collected earlier and saved to a log. First, set up the simulation by choosing the log you want and set a display interval. Then open the connection to display the locations from the log on the map. You can use any point or line feature class for the simulation data.
About creating new annotation features
NOTE: Creating and editing standard annotation is available in ArcView. However, you can only create and edit feature-linked annotation with an ArcEditor or ArcInfo license.
To create, edit, or delete geodatabase
annotation, you must first
start an edit session. The Editor and Annotation toolbars provide the tools you need to create new annotation features. The Annotation toolbar allows you to choose the construction method—horizontal, curved, leader line, and so on—and the symbol of your new annotation. You'll enter the text of your annotation in the Text box on the Annotation toolbar, but you can press the A key and change the text for constructing new annotation.
You use the Sketch tool with the Construction dropdown list to create annotation. The one-click buttons on the Annotation toolbar are simply shortcuts that activate the Sketch tool and a particular construction method. You can add a button from the Advanced Edit tools list in the Customize dialog box that allows you to construct curved or follow feature annotation with a single click.
If you want to use the
Convert Labels to Annotation command or the Annotation toolbar editing and construction tools with annotation feature classes created in ArcGIS 8, you'll first need to upgrade your geodatabase and use the Update Annotation Feature Class tool in ArcToolbox. It is important to note that you won't be able to view updated annotation in ArcGIS 8. You can always view earlier versions of annotation in later versions of ArcGIS. Geodatabases and annotation feature classes created in ArcGIS 9 do not need to be updated.
To learn more about working with annotation, see
About annotation or
Annotation in the geodatabase
To create, edit, or delete geodatabase
annotation, you must first
start an edit session. The Editor and Annotation toolbars provide the tools you need to create new annotation features. The Annotation toolbar allows you to choose the construction method—horizontal, curved, leader line, and so on—and the symbol of your new annotation. You'll enter the text of your annotation in the Text box on the Annotation toolbar, but you can press the A key and change the text for constructing new annotation.
You use the Sketch tool with the Construction dropdown list to create annotation. The one-click buttons on the Annotation toolbar are simply shortcuts that activate the Sketch tool and a particular construction method. You can add a button from the Advanced Edit tools list in the Customize dialog box that allows you to construct curved or follow feature annotation with a single click.
If you want to use the
Convert Labels to Annotation command or the Annotation toolbar editing and construction tools with annotation feature classes created in ArcGIS 8, you'll first need to upgrade your geodatabase and use the Update Annotation Feature Class tool in ArcToolbox. It is important to note that you won't be able to view updated annotation in ArcGIS 8. You can always view earlier versions of annotation in later versions of ArcGIS. Geodatabases and annotation feature classes created in ArcGIS 9 do not need to be updated.
To learn more about working with annotation, see
About annotation or
Annotation in the geodatabase
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