Inset map

What it does

At high zoom, a map can stop showing where you are. The inset map is a smaller map in the corner, held a few zoom levels out, with a box around the main map's current view.

It follows the main map. Pan the main map and the box moves. Zoom the main map and the inset keeps its offset.

Using it

Glance at it. The rectangle is the area of the main map.

Where the control allows it, the inset can be collapsed to get it out of the way, and restored when you want the context back.

In your own map

Add insetMap with a position, usually a corner the main map's other controls are not using.

• zoomOffset: how many levels out from the main map, as a negative number. -5 is a good starting point: enough to show the region and close enough to still be recognizable.
• baseScale: pin the inset to a constant scale instead of following the main map's zoom, for a map that should always show the same country.
• styleUrl or background: what the inset itself draws. A plain, quiet background usually works well because the inset is context.
• collapsed, minimizable: start it folded away, and let the reader fold it.

Extending it

The inset is a second map instance, not a picture. It can have its own background and projection, but it also makes its own tile requests.