Use inference constraints

Inference Inference is a constraint mode that uses your current snap settings to snap the pointer to inferred geometric relationships between the current vertex and existing feature geometry. Inference is turned on or off on the status bar at the bottom of the active map.


Inference is primarily intended for drawing rectilinear shapes that represent objects in built environments. Using Inference with dense vertices can degrade map performance.

To turn on and use inference constraints, complete the following steps:

  1. On the status bar at the bottom of the active map, click the Inference button Inference.

    Alternatively, hover over the button until the pop-up menu appears and click the Inference toggle button.

    Inference toggle button
  2. On the ribbon, click the Edit tab. In the Snapping group, click the drop-down arrow, and enable one or more of the following snap agents:

    Edge Edge

    Snap to inferred line extensions displayed as straight lines.

    Intersection Intersection

    Snap to inferred intersections of two or more lines or edges.

    Point Point

    Snap to inferred perpendicular intersections displayed as squares.

    Vertex Vertex

    Snap to inferred distance radial intersections displayed as circles.

    To use Inference with feature geometry you are actively drawing, click Snapping Settings Options and check the Snap to sketch check box.

    Snapping Settings

  3. In the Create Features pane, click a polyline or polygon feature template, and click the Line tool Line or Polygon tool Polygon.
  4. Click the map to create a vertex.

    Create at least one segment if you are using Inference to initially constrain the pointer to feature geometry you are actively drawing.

  5. Hover over a segment of a nearby feature or the feature geometry you are actively drawing.

    Inference briefly flashes the segment it is analyzing and displays the related constraints to which you can snap.

  6. Hover over the related constraints allowing the enabled agents to provide feedback and click the pointer to snap the geometry to the constraint. Repeat this step using the tools on the construction toolbar until the feature is fully developed.

    The perpendicular constraint appears as a square and represents the extended intersection of two segments.

    Inferred perpendicular intersection

  7. Click Finish Finish, or press the F2 key to finish the feature.

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