Minimum Convex Polygon Background

Cartography · Graphic Backgrounds · ribbon tool with its own window · by Jeff Jenness

Works at every ArcGIS Pro license level

Summary

Draws the minimum convex polygon around the selected graphic or layout elements, then groups the polygon and the selection together with the polygon underneath. The minimum convex polygon is the smallest polygon with no inward bends that holds every selected shape, the outline a rubber band would take if it were stretched around them. It gives a tight, simple backdrop for a scattered set of elements, closer than a rectangle and tidier than a traced outline.

A legend titled Grand Canyon Elevation, a compass north arrow and a 10 kilometer scale bar in the lower left corner of a tinted relief map, all sitting on one pale gray, partly transparent background with five straight sides and rounded corners, a dark outline and a soft shadow, cut diagonally across its upper right so that it stays clear of the terrain — One background for a legend, a north arrow and a scale bar. The minimum convex polygon wraps the three of them as a set, and its slanted side leaves the map uncovered where a rectangle would have hidden it.

How it works

Each selected element is traced, either from the geometry it is built from or from its shape as drawn. Curved outlines are followed closely, so the bulge of an arc is not cut off. The convex hull of all the traced shapes together is computed, the buffer is applied to the hull, and the result is drawn with the chosen symbol and grouped behind the selection.

The result is always a single polygon with no holes, however many elements are selected and however far apart they are. An element that has been rotated is traced in its rotated position.

If the selection amounts to a single point or a straight line, the hull has no area. Give a buffer size greater than zero and the background becomes the buffer around it. The tool says so if the buffer is missing.

What to select first

The tool works on selected elements: graphics in a map's graphics layer, or elements on a layout (text, pictures, legends, north arrows, scale bars, map frames and so on). It does not work on features in a dataset. Select one element or several, then click the tool. If nothing is selected, the tool says so and stops.

The Cartography Tools gallery open on the ribbon, with the Minimum Convex Polygon button, in the Graphic Backgrounds row, outlined in blue — Where to find it: **Minimum Convex Polygon** is in the *Graphic Backgrounds* row of the *Cartography Tools* gallery, in the Cartography group of the *Wildlife and Forestry* tab.

On a map, the selected graphics must all be in one graphics layer. A selection that spans two graphics layers is turned away with a message.
If a selected element already belongs to a group, the whole group comes along. The tool never pulls a group apart.

A tour of the dialog

The minimum convex polygon background is especially good for making a background for a group of graphics, such as this legend, north arrow and scale bar:

A tinted relief map of the Grand Canyon with a legend titled Grand Canyon Elevation, a compass north arrow and a 10 kilometer scale bar placed directly on the map in the lower left corner, with nothing behind them — Three separate elements placed directly on the map.

With all three selected, the tool is set up like this:

The Minimum Convex Polygon dialog: a graphic name of MCP Background, the Design symbology button with a gray gradient swatch, fill transparency 30, outline transparency 0, Fit MCP around set to The symbolized shape, a buffer size of 0.1 inches, and the Drop shadow box checked with black, opacity 60 percent, angle 135 degrees, distance 5 points, spread 0, size 5 points and 10 layers, with a blue help button beside OK and Cancel — The dialog: a gray gradient symbol at 30% fill transparency, the polygon fitted around the elements' symbolized shapes and buffered by 0.1 inches, and a drop shadow at its starting settings.

That produces this:

The same map with the legend, north arrow and scale bar now sitting together on one pale gray, partly transparent polygon with rounded corners, a dark outline and a soft shadow. The polygon's upper right side runs diagonally from above the legend down to the end of the scale bar — One background behind all three. The buffer rounds the corners and leaves a margin around the elements, and the shadow lifts the panel off the map. The four pieces are now one group and move together.

Control	Explanation
Graphic name	Optional. The name given to the new polygon. On a layout it is the name shown in the Contents pane; on a map, graphics are not listed there, and the name shows in the Element pane when the graphic is selected. The new group is named after it, with “Group” added. Left blank, the polygon gets ArcGIS Pro's default name and the group is named Minimum Convex Polygon Group.
Symbology / Design symbology…	Opens ArcGIS Pro's own Format Polygon Symbol editor, gallery included, so the background can carry any polygon symbol: a solid fill, a gradient, a hatch, any outline. The swatch beside the button previews the chosen symbol before transparency is applied. The starting symbol is a pale yellow fill. The Format Polygon Symbol editor, with its Gallery of ready-made symbols on one tab and the symbol's layers on the other. Here, a 1-point black outline over a gradient fill.
Fill transparency (%)	0 to 100. Applies to the interior fill only. Gradient fills are made transparent evenly across the whole gradient.
Outline transparency (%)	0 to 100. Applies to the outline only, so a see-through fill can keep a solid border, or the reverse.
Fit MCP around	The element's geometry uses the shape the element is built from: the vertices of a drawn polygon or line, with no allowance for the thickness of its symbol. The symbolized shape uses the element as it is drawn, symbol widths included, so a thick outline or a large marker is fully covered. For elements that have no geometry of their own to trace (text, legends, pictures, map frames and the like), both choices use the element's drawn bounds.
Buffer size	Optional. 0 draws the exact minimum convex polygon. Positive values expand it and negative values shrink it. On a map the buffer is in the units of the map's coordinate system, named beside the box. On a layout choose millimeters, centimeters, inches or points.

Click OK and the polygon is drawn. Cancel closes the dialog and changes nothing.

Drop shadow

Check Drop shadow and the tool draws a soft shadow beneath the polygon, the kind that makes a panel look as if it is floating a little above the map. The controls follow the drop shadow settings in Adobe Photoshop, so they will be familiar if you have used those.

The legend example in the tour of the dialog above has one, and the dialog pictured there shows the settings that made it.

Control	Explanation
Color	The color of the shadow. Black or a dark gray is usual.
Opacity	How dark the shadow is at its darkest, from 0 to 100%.
Angle	The direction the light comes from. The shadow falls on the opposite side. Click or drag on the dial to point it at the light, or type the angle in degrees, measured counterclockwise from east: 90 is light from the top, and 135 is light from the upper left, the usual choice on a map.
Distance	How far the shadow is shifted away from the light. A larger distance makes the polygon appear to float higher. 0 leaves the shadow directly underneath, showing evenly on all sides as a soft glow.
Spread	How much of the soft edge is made solid. 0 gives the softest edge. 100 gives a hard-edged shadow.
Size	The width of the soft edge. 0 gives a hard edge with no softening at all.
Layers	The number of pieces the soft edge is built from, 1 to 60. More layers give a smoother edge.

Distance and Size are in points on a layout, and in the units of the map's coordinate system on a map.

How the shadow is made. ArcGIS Pro graphics cannot be blurred, so the soft edge is built from a stack of plain polygons. Each is a copy of the polygon's outline, shifted away from the light, with a solid fill that is mostly transparent. The copies are made in a graded series of sizes, the largest a little bigger than the outline and the smallest a little smaller. Where more of them overlap, the shadow is darker, so it fades smoothly from nothing at its outer edge to the full opacity inside. The opacity of each copy is worked out so that the darkest part is exactly the opacity you asked for, however many layers you choose.

The shape of the polygon itself is cut out of every layer. The shadow therefore lies around the background and never underneath it, and a partly transparent background keeps its own color and is not darkened by its shadow.

The shadow's layers are ordinary polygon graphics. They are grouped together, and that group sits below the polygon inside the new group.

What you get

One new polygon graphic, placed behind the selected elements, and one new group that holds the polygon and everything that was selected, along with the drop shadow if one was asked for. Because they are grouped, the background and its contents move, resize and copy together.

Layouts give you more room to work ArcGIS Pro is much more flexible with graphic elements on a layout than on a map. On a layout, the Contents pane lists every element. Expand the group there and you can select the polygon by itself, edit it, hide it and show it again. On a map, the Contents pane shows only the graphics layer and does not list the graphics inside it. A group can only be selected as a whole, so its members cannot be picked out one at a time. To change the polygon on a map, select the group and ungroup it (right-click the group, or use Arrange on the Graphics tab), make the change, then select the pieces and group them again. Be careful with the Visible check box in the Element pane too: on a map, a graphic that has been made invisible can no longer be clicked, and with no list to pick it from there is no way to select it again and turn it back on.

The polygon is an ordinary ArcGIS Pro graphic. Nothing about it is special once it is drawn, so it can be edited by hand like any other: select it and use the Element pane to change its symbol, its size, its position or its name.

Nothing else is altered. The selected elements keep their own symbols, sizes and positions.

The tool remembers your choices

After a successful run, the symbol and every setting in the dialog are stored with the project, so the next background starts where the last one left off and a set of backgrounds comes out matching. Each of the four Graphic Background tools keeps its own settings. The graphic name is never remembered. The settings are saved when the project is saved.

Recommended citation

Jenness, J. 2026. Minimum Convex Polygon Background. Wildlife and Forestry Tools add-in for ArcGIS Pro, v. 1.113.62.1 (October 2026). Jenness Enterprises. Available at: https://github.com/JeffJenness/Wildlife_Tools.

Credits

By Jeff Jenness, Jenness Enterprises (www.jennessent.com).

Licensing information

Works at every ArcGIS Pro license level (Basic, Standard, Advanced). No extension licenses are required.

Circle Background — a circle behind the selection, the natural fit for a compass rose or any round element.
Rectangle Background — a rectangle behind the selection, with square or rounded corners.
Polygon Background — a background that follows the actual shape of the selected elements.
Create Shadow Polygons — a soft shadow of fading rings around the polygons of a feature class, where these tools shadow graphics.