ArcGIS Pro

Introducing editing with Inference in ArcGIS Pro

ArcGIS Pro editors, did you notice a button in the status bar of your maps in ArcGIS Pro in between the editing Reference Grid button and Ground To Grid corrections button?

Location of Inference toggle button
Status bar buttons location
The Inference toggle is located in the status bar in the lower of the map

Did you click it? If not, you should.

This button unlocks an editing capability that was introduced in ArcGIS Pro 2.7 called Inference. It allows you to quickly create regular shaped features while sketching. Think right angles and aligned features. This will be especially helpful for those of you who work with built environments such as floor plans, site plans, building footprints, or any project where you need to quickly create squared up and aligned features.

You’ll start with an example: creating a line. This simple example illustrates the core features of Inference, but before working with Inference, you need to prepare the map where you are working.


Since Inference works in conjunction with Snapping, you will turn on Snapping and the Snapping Agents. At a minimum, turn on the Edge and Intersection snapping agents, as well as the Snap to sketch setting.

Shows snapping agents turned on
Shows the snapping settings dialog

Create a line

Now that you have both Inference and Snapping enabled, you’re ready to create your line.

From Create Features, choose a line template and the Line tool, and click two points on the map to create a straight segment. Everything looks normal:

inference rays
A line segment with inference "rays"

Or does it? What are those blue lines radiating from the endpoint? Those are inference rays, and they go in two directions: parallel and perpendicular. You can snap to rays while sketching features, so if you want to constrain the next segment perpendicular to the last, hover over the perpendicular ray and let edge snapping take over:

Snapping to Inference rays
You can snap to Inference rays

What if you want to make the next segment perpendicular but also the same length as the first? With Inference, you can. Hover over any segment in the sketch and that segment flashes for a moment, and you’ll get the following:

Distance radii appear
The inferred segment flashes and distance radii appear.

A quick flash and more Inference help appears. The circles are distance radii (there is only one now, but more will show up if you infer from two or more segments that intersect).

So now that you have inference rays and radii being previewed on the map, you can now snap to the intersection of the perpendicular ray and the distance radius, like so:

Second segment
The second segment is the same length and perpendicular to the first.

What about curved segments? Inference works with the Tangent Curve Segment construction tool: 

Tangent Curve Segment construction tool
Tangent Curve Segment construction tool

Once you switch construction tools, you’ll see a different set of inference rays in directions that are inferred from the previous segment in 45-degree increments:

Tangent Inference rays appear when you using the Tangent Curve Segment tool with Inference
Tangent Inference rays appear when you using the Tangent Curve Segment tool with Inference

In this case, you will snap to the intersection of the inferred 90-degree angle and the inferred length of the previous segment, heading back to the beginning point:

The third segment is a curve with an arc length equal and tangent to the previous.
The third segment is a curve with an arclength equal and tangent to the previous.

You can snap and close this polyline on itself to end up with this doorway shape:

A single line created using Inference

All together now

Here it is all together:

How it looks all together

Other capabilities

With Inference, you can infer from more than just the current sketch, and I’ll be covering these capabilities in future articles. For now, here is a list of all the capabilities:

The metaphorical doorway is now open. I welcome you to find new and interesting ways to use Inference in your daily work. If you find something useful and want to share with others, let us know in the comments. Let Inference be your guide to creating squared up and aligned  features.

About the author

Scott Harris

I am a Product Engineer for the ArcGIS Pro Editing team. I have been working in the GIS field since early the early 2000’s. I received a Master of Science degree in Geoenvironmental Studies from Shippensburg University in Pennsylvania in 2013 with a focus on land use planning and remote sensing. I started at Esri in 2014, where I worked in Support Services helping users succeed with Esri software, and now I help design the Editing experience in ArcGIS Pro.

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