Customizing your map extent

A map extent defines the geographic boundaries for displaying GIS information within a data frame. These boundaries contain top, bottom, left, and right coordinates. These are the edges of the map extent. For example, the image below shows a map centered on the U.S. state of Alabama. The map image also shows the extent boundaries. The units for these values are the same as the map units. In this case, the map is projected in Albers, and the map units are meters.

Example map extent

Map extents are affected by map scale. As you zoom in or out of a map, the map extent changes, provided that the data frame size on the page remains the same.

In some cases, you will want to control the map extent. For instance, you might only be interested in a geographic subset of your data and want to limit the map user to this area. Or, you may want to limit users to a particular map scale while allowing them to pan to different locations. Also, you may want to derive the map extent of one data frame, for example, an inset map, based on the map extent of a different data frame.

ArcMap provides a number of options in which you can control a map's extent:

The default extent option is Automatic. Notice that with this option there are no other controls or options available in the Extent portion of the dialog box. Appropriate controls are added based on the extent option chosen.

Setting the extent on the Data Frame tab of the Data Frame Properties dialog box

Automatic

This is the default option. This option places no restrictions on map navigation. You can freely pan, zoom, or use bookmarks. When you do, the map's extent and scale change automatically. If you change the data frame size on the layout, the map extent and scale will change as the data frame changes.

Fixed Extent

This option keeps the map extent constant. The geographic boundaries of the map—the top, bottom, left, and right coordinates—are specifically defined. These values should be in map units.

Using the Fixed Extent option

There are six ways that you can set a fixed extent:

If you set Fixed Extent while in data view and the aspect ratio (height /width) of the data view window is different than the aspect ratio of the data frame on the page layout, the data frame height and width on the page layout will snap to match the aspect of the data view. If you intend to create a map layout using a fixed extent, you should set the fixed extent while in layout view.

Map navigation is restricted for this data frame. You cannot pan, zoom, or use bookmarks. If you choose this option, appropriate map navigation tools and commands will be unavailable. If you resize the data frame on the page layout, the map scale will change to keep the extent constant.

If you resize the data frame on the page layout, the map scale will change. The geographic area displayed in the map does not change, as illustrated below:

Increase the size of the data frame by dragging the frame across the page.The geographic extent of the map remains the same and the map scale changes accordingly.

Fixed Scale

This option keeps the map scale constant. Enter the scale you want to use. You can enter the scale in absolute format, such as 1:34,000, or in relative format, such as 1 inch = 5 miles. You can enter scales in absolute or relative format irrespective of what format the scale control is currently using. When you enter a scale, it automatically is converted to the current scale format being displayed.

When you type scales into this field, they remain at the top of the list for the duration of your session so that they can be easily accessed again in this dialog box or anywhere else scale is specified. To permanently add or remove predefined scales to or from this list, use the <Customize This List> option, which also lets you change the format that is used to display scales. Customizations you make to the list of predefined scales and how scale is displayed are stored as ArcMap settings on your computer; they are not stored in the map document itself so will not be in effect if the map document is opened on a different machine.

A variety of scale formatting is supported:

You can pan the map to a new location, but you cannot zoom to a new map scale. If you resize the data frame on the page layout, the map scale will remain. The geographic area displayed in the map will change, as illustrated below:

When using fixed scale, you can pan the map and change the data frame extent and the map scale will remain the same.

Other Data Frame

This option derives the map extent for the data frame by taking the current geographic extent of a different, specified data frame. If you want, you can buffer this extent by a specified margin. The margin can be specified in map units, in page units, or as a percentage of the other data frame's extent. You can also use intersection of specified layer features (from the data frame whose extent you are customizing) with the extent of the selected (other) data frame.

Using the extent of another data frame to specify the data frame extent

There are a number of ways in which you can use this option. The example below shows an overview map, the smaller map on the right, whose extent is based on the extent of the main data frame and includes a margin of 0.1 inch.

An example showing an overview map, the smaller map on the right, whose extent is based on the extent of the main data frame and includes a margin of 0.1 inch.

The margin is measured from the edge of the selected data frame's geographic extent to the closest edge of the data frame whose properties you are editing. The margin value is applied to each side of the horizontal and vertical axes. Since the aspect ratios (width/height) of the two data frames are not the same, the 0.1 margin is only applied along one axis. The margin will be larger along the other axis. The size of the difference depends on the difference in aspect ratio. If the two data frames share the same aspect ratio, the margin along the vertical and horizontal axes will be the same. If you use map units, you will see similar results.

NoteNote:

The map extent updates if the geographic extent of the active data frame changes. This is important if you are using Data Driven Pages. Data Driven Pages allow you to quickly and easily create a series of layout pages from a single map document. A feature layer, or index layer, divides the map into sections and generates one page of output per section.

When Data Driven Pages are enabled for a map document, the extent for the primary, or Data Driven Pages, data frame is tied directly to data. The primary data frame is the data frame driving the map extent for the pages. You cannot interactively change this data frame's extent through map navigation tools or commands. Also, you cannot change the map extent option on the Data Frame Properties dialog box. The Extent arrow is unavailable.

However, you can still change the map extent properties for any secondary, or inset, maps. Doing so can achieve a number of desirable effects. For example, the Data Driven Pages example below shows a page from a map book for U.S. states. Each page contains two data frames of equal prominence. One data frame shows median home values by county while the other data frame displays the percentage of homes for rent. The goal is to keep the map extent for both data frames consistent with each other as each page is generated.

Example of deriving data frame extent from Data Driven Pages

Learn more about Data Driven Pages

You can also derive a map's extent by taking the combined extent of features from a specified layer that intersect with the extent of another data frame. For example, you have divided a city's geography into a grid of 60 cells. The map contains a layer, GridParcels, that represents this grid, and you want to map each individual grid cell. You also want to include an inset map highlighting this grid cell's location. One way to do this is to use an extent locator. The example below shows a map for grid cell E4. The inset map in the bottom right shows all grids and highlights grid E4 in a red outline.

Example of deriving a map's extent by taking the combined extent of features from a specified layer that intersect with the extent of another data frame.
Learn more about using extent indicators

Perhaps you don't want to display all grids in the inset map; you just want to display the adjoining, or intersecting, grid cells in your inset map. You can do this by defining the extent of the inset map to use the other data frame (the main map) and to use GridParcels as the intersecting layer. The inset map will zoom to the extent of the geographic extent of the other data frame plus the combined geographic extent of each feature in the selected layer that intersects the extent of the other data frame plus the assigned margin.

TipTip:

If you want the data frame extent to be flush against the edge of the intersecting features, enter a margin of 100 percent or 0 if you want to use map or page units. If you want a bit of a buffer between the edge of the data frame and the intersecting features, enter a margin greater than 100 percent or a value greater than 1 if you are measuring in map or page units.

As you can see in the example below, the inset map highlights the current grid cell displayed in the main map and displays the surrounding cells. The inset map changes accordingly based on the current extent of the Main Map. This can be very useful when you are using Data Driven Pages.

Example showing inset map displaying only index grids that intersect with the current grid.

You should be aware that the scale of the inset map can change. In the example below, there is only one intersecting feature. As compared to the inset map scale for grid cell E4, which has GridParcels features on all sides, the inset map scale for grid cell F9 is smaller, since this grid cell has only three intersecting features.

Example of the inset map scale changing when the grid cell is smaller.

Extent Units

The extent is displayed in map units. ArcMap uses the following abbreviations for map units:

Metric units

Imperial or international units

Geographic

Other

Map extent options and their effect on map navigation

There are many ways in which you can navigate your map. Map extent options affect your ability to navigate your map. The following table identifies which map navigation tool can be used with the data frame based on the extent option placed on the data frame.

Automatic

Fixed extent

Fixed scale

Other data frame

Tools toolbar: Zoom In

Yes

No

No

No

Tools toolbar: Zoom Out

Yes

No

No

No

Tools toolbar: Pan

Yes

No

Yes

No

Tools toolbar: Full Extent

Yes

No

No

No

Tools toolbar: Fixed Zoom In

Yes

No

No

No

Tools toolbar: Fixed Zoom Out

Yes

No

No

No

Tools toolbar: Previous Extent

Yes

No

Yes

No

Tools toolbar: Next Extent

Yes

No

Yes

No

Tools toolbar: XY

Yes

No

No

No

ID Results context menu: Zoom To

Yes

No

No

No

ID Results context menu: Pan To

Yes

No

Yes

No

Find Results context menu: Zoom To

Yes

No

No

No

Find Results context menu: Pan To

Yes

No

Yes

No

Selection context menu: Zoom To Selected Features

Yes

No

No

No

Selection context menu: Pan To Selected Features

Yes

No

Yes

No

Data Frame context menu: Full Extent

Yes

No

No

No

Data Frame context menu: Go Back To Previous Extent

Yes

No

Yes

No

Data Frame context menu: Go To Next Extent

Yes

No

Yes

No

Data Frame context menu: Fixed Zoom In

Yes

No

No

No

Data Frame context menu: Fixed Zoom Out

Yes

No

No

No

Data Frame context menu: Center

Yes

No

Yes

No

Data Frame context menu: Zoom To Selected Features

Yes

No

No

No

Data Frame context menu: Pan To Selected Features

Yes

No

Yes

No

Table context menu: Zoom To

Yes

No

No

No

Table context menu: Pan To

Yes

No

Yes

No

Table context menu: Zoom To Selected Features

Yes

No

No

No

Layer context menu: Zoom To Layer

Yes

No

No

No

Layer context menu: Zoom To Make Visible

Yes

No

No

No

Bookmarks

Yes

No

Yes*

No

*If data frame has a fixed scale, bookmarks can be used. However, the fixed scale is maintained; therefore, the bookmark may not be displayed using the original map scale that the bookmark was created under.

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8/20/2010