Specifying a label buffer distance to change the space between labels

Some labeling situations can create crowded areas where labels are placed close to each other. This can decrease the readability of a map, especially when it becomes unclear which features are being labeled. The Maplex Label Engine's label buffer parameter allows you to increase the clarity of such maps by specifying a buffer distance around each label in which no other labels will be placed. By increasing the buffer size, a larger amount of white space is created around labels, making it easier to distinguish one label from another.

When a label buffer is specified, the Maplex Label Engine uses this buffer as a guide for the trial positions and places the labels with their buffer if there is space available. If creating a buffer for a label would result in unplaced labels, the label engine will not create the buffer, resulting in closely placed labels. In this situation, no labels will be dropped from placement.

If the Hard constraint check box is checked, the buffer is respected regardless of available space. This results in well-spaced labels but also in the possibility of many unplaced labels.

Steps:

1. Enable the Maplex Label Engine.
2. Click the Label Manager button on the Labeling toolbar.
3. Choose the label class under the layer you want to modify.
4. Click the Properties button.
5. Click the Label Density tab.
6. Modify the label buffer value as a percentage of font height. The default is 15%, and the maximum is 50%.

   Very large label buffers restrict the amount of available space for placing labels and may result in fewer labels being placed.

7. Optionally, check the Hard constraint check box. This allows the label buffer to be applied to each label in the class regardless of available space. This may increase the number of unplaced labels. When unchecked, the label buffer is only applied if space is available.
8. Click OK to close all dialog boxes.

Tip:

If you are using label offsets, you should set the label buffer to be slightly larger than the preferred label offset. This helps avoid ambiguity on the map.

Tip:

You can also open the Placement Properties dialog box by clicking the Placement Properties button on the Labels tab on the Layer Properties dialog box for the layer you want to label.