Highlight portions of basemap

Question

I have a map with two main components:

1. a polygon containing a number of shapefiles; and
2. a colored basemap (from ArcGIS) that covers the entirety of the polygon and beyond.

Is there a way to "gray out" the portions of the basemap that are outside the boundary of the polygon and retain the colors of the basemap within the polygon area?

My end goal is to highlight and draw the viewer's attention to the polygon.

Answer 1

What you essentially want is a vignette or feathering effect added to you map in which the edges gradually soften and eventually blend into the background.

In your case, I would create a master feature class to store all your vignette features. If you have to create this effect for multiple boundaries across your map, create vignette features for each boundary and append all to your master vignette feature class.

You can easily create the vignette features using the Buffer Wizard tool in ArcMap. To add this tool to your layout go to customize-> customize mode-> commands -> search for buffer wizard -> drag and drop anywhere in your layout.

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Here are some resources that I have come across in the past that may be helpful:

• Design principles for cartography
• Figure-ground: Whitewash
• Figure-ground: Feathering
• Figure-ground: Drop shadow
• How to produce tint bands for boundaries
• How to display nebulous boundaries between regions with indistinct edges?

Answer 2

I don't know of anything build to do what you're trying, but I do have a bit of a work around if you are trying to create a static map...

I would digitize an additional polygon, and then use the erase GP tool with your "highlight" polygon to create a hole in the middle. You can then symbolize the new donut polygon with a grey shade and play with the transparency in the layer properties to make your area of focus appear to pop.