Changing the spatial extent

When you create a standalone feature class or feature dataset, you can change the spatial extent by manually entering new values for the minimum x and y coordinates.

You can change the Min X and Min Y values by entering new coordinates directly into the dialog. The Max X and Max Y values update automatically to reflect the new minimum values. In this example, the user is importing the spatial reference from another feature class and changing the spatial extent to allow for data expansion to the west and south.

If you know the spatial extent that your data will require, you can simply enter the appropriate Min X and Min Y values. You should check the updated Max X and Max Y values to make sure they are equal to or larger than the maximum x and y coordinates required for your data. If they are not, you will need to change the precision to a lower value.

You can determine the required minimum and maximum x,y coordinates based on the minimum bounding rectangle for your data.

If you don't know how large a spatial extent your data will require, you can center your data in geodatabase coordinate space and explicitly define your precision. This method would provide the maximum amount of room for your data to grow in all directions.

Centering your data: planning for unknown growth

When you create a new feature class or feature dataset, you may not be able to anticipate how large a spatial extent the data will require in the future. The solution is to shift the geodatabase coordinate space so that it is centered around your current data, thus allowing for growth on all sides.

To shift the geodatabase coordinate space, you need to calculate the difference between the middle of your current dataset and the middle of geodatabase coordinate space.

Consider this example: A source dataset with a Min X value of 200,000; a Min Y value of 440,000; Max X and Max Y values of 1,000,000; units of meters; and a precision of 1,000.

First, find the center of geodatabase coordinate space in storage units:

2,147,483,648 / 2 = 1,073,741,824

Note: 2,147,483,648 is the largest integer value that can be stored in a geodatabase.

Next, convert the center in geodatabase storage units to map units by dividing by the precision:

1,073,741,824 / 1,000 = 1,073,741.824

The second part of the process is to find the center of your current dataset:

(DataMinX + DataMaxX) / 2
(200,000 + 1,000,000) / 2 = 600,000

(DataMinY + DataMaxY) / 2
(440,000 + 1,000,000) / 2 = 720,000

Finally, calculate the shift by finding the difference between the center of your data and the center of the geodatabase coordinate space (in map units):

DataCenterX – GDBCenter = X Shift
600,000 – 1,073,741.824 = –473,741.824

DataCenterY – GDBCenter = Y Shift
720,000 - 1,073,741.824 = –353,741.824

In the Spatial Reference Properties dialog, enter the X Shift value (–473,741.824) for the Min X value and enter the Y Shift value (–353,741.824) for the Min Y value. This will shift the geodatabase coordinate space to the left and down.