This step not required for ALL geodatabases.
It is REQUIRED for those using ESRI ArcPad to collect data AND processing that data with
Trimble GPS Analyst
1. To enable the GPS Analyst extension
From the ArcCatalog menu bar, select Tools / Extensions
Check the box next to Trimble GPS Analyst
The GPS Analyst extension is now activated
2. To GPS-enable the geodatabase and feature classes
You can GPS-enable a geodatabase at the same time that you create the geodatabase, or later, once it contains GIS features. For this exercise, we will enable the GDB now before it contains any data.
Right-click on the Training_Day1 geodatabase and choose Properties
Click on the Trimble GPS Analyst tab
Place a checkmark next to the GPS-enable geodatabase box
Place a checkmark next to the feature classes you wish to GPS-enable.
Click the Select All button to GPS-enable all listed feature classes.
3. To specify accuracy values for validation
You can specify or change the accuracy required for a feature class at any time. For this exercise, we will specify the required accuracy now, before we check out the data to ArcPad.
4. To specify accuracy values for all feature classes
Return to the Trimble GPS Analyst tab
Click the Feature Class Properties button
In the Store average estimated accuracy box, enter the attribute field name avg_accuracy
In the Store worst estimated accuracy box, enter the attribute field name worst_accuracy
In the Accuracy required for validation box, enter the value 3.000 ft
The completed window should look similar to this –
For this first exercise, 3 feet is an acceptable horizontal accuracy. This value is based on the specifications of your GPS receiver and the goals of the data you are trying to collect.
This sets the properties of all GPS-enabled feature classes to the same values. To edit the individual feature classes, right-click on that feature class and choose Properties.
Where you entered 3.000 ft for accuracy required for validation, 0.0914 m would have been the mathematically equivalent and a valid entry in the dialog box. The below table display ArcGIS standards for unit abbreviations.
Nautical miles nm
Decimal degrees dd
5. To view the required accuracies
Now all the feature classes in the geodatabase have the same accuracy requirements for validation.
Click OK to close the Database Properties window
6. To view the results of your efforts
Note the appearance of the GPS Sessions folder button and its hierarchy within the geodatabase of the resulting feature dataset in ArcCatalog.
7. To view the created accuracy fields in the attribute table
View the properties of any one of the feature classes you have GPS-enabled.
Hint: Right-click on any feature class and choose Properties
Click on the Fields tab
What new fields have appeared and of what data types are they?
In this exercise, we specified a WGS-84 coordinate system for our feature dataset (and subsequently, the feature classes). Therefore, a geographic transformation will not need to be selected for our exercise.
Coordinate systems other than WGS-84
If the feature classes in the geodatabase(s) at your office are not referenced to the WGS-84 coordinate system, a geographic transformation will need to be selected. This specifies which datum transformation GPS Analyst will use to correctly convert GPS data from its stored WGS-84 coordinates to the coordinate system of your GIS.
ArcGIS uses the EPSG codes for datum transformations.
NAD_1983_To_WGS_1984_1 NAD 83 (1986) - "zero" datum shift
NAD_1983_To_WGS_1984_2 Alaska Aleutians
NAD_1983_To_WGS_1984_4 United States - ITRF94
NAD_1983_To_WGS_1984_5 United States - ITRF96
Transform _1 is a null transform where all parameters are held at 0 and data does not move at all. It is the safest choice to define your data as NAD83 in the ArcGIS environment without shifting your data as collected by GPS.
Transform _5 is an older transform, which moves data from the older ITRF96 datum. ArcGIS has not yet incorporated the latest parameters to move data from WGS-84 to the most recent ITRF00. For application requiring the highest accuracy, consult with your GIS Specialist to manually install the latest transformations in ArcGIS.
See the Datum 101 and DatumSection on this site, and
Consult with your local GIS specialist for the correct settings for your location and data.