Overview#
Good sketches rarely exist in isolation. You need to locate a hole relative to an existing edge, trace the outline of a face, or capture where a body crosses your sketch plane. Fusion has a family of commands that bring existing 3D geometry into the active sketch. According to Autodesk's Sketch help, they all live in the Sketch > Create panel under Project/Include. The help lists six tools; Spun Profile and Isoparametric Curve are summarized after the table.
| Command | In one line |
|---|---|
| Project | Projects faces, edges, points, or bodies onto the sketch plane |
| Intersect | Captures points, edges, work geometry, and sketch curves that cross the sketch plane |
| Include 3D Geometry | Brings edges, work geometry, and sketch curves into the sketch as 3D geometry |
| Project To Surface | Projects sketch curves, edges, vertexes, or work points onto selected faces |
| Intersection Curve | Creates a 3D sketch curve from intersecting geometry |
| Spun Profile | Projects the spun profile of a solid body about a selected axis into the sketch |
| Isoparametric Curve | Extracts UV curves from a surface as sketch geometry |
Projected and intersected geometry is generally associative: it stays linked to its source and updates when the source changes. That is both a strength and a hazard; this page explains how to use it safely.
Where to find it#
- Sketch tab > Create > Project/Include (a flyout with the commands above).
- Project shortcut: not listed in Autodesk's help. P is the commonly used default, so confirm it in your install.
- You must be inside a sketch. Start one with Create Sketch, or Edit Sketch an existing one. The 3D commands (Project To Surface, Intersection Curve) create 3D sketch geometry; Autodesk's help notes that Project To Surface puts the projected result in a new sketch, and that for Intersection Curve the curve and the geometry it intersects cannot be in the same sketch.
Step by step: Project#
- Enter a sketch.
- Choose Create > Project/Include > Project (or press P).
- Set the Selection Filter in the dialog: Specified Entities (faces, edges and points) or Bodies.
- Select the bodies, faces, edges, or points to project onto the sketch plane.
- Leave Projection Link checked to keep an associative relationship, so the sketch updates when the source changes. Uncheck it for non-associative geometry.
- Click OK or press Enter. The projected geometry appears as purple projection geometry and is locked by default.
Projecting a body produces closed profiles for the body's silhouette on the plane, ready to be used by features. Projecting a face projects its boundary edges; the face outline can then be offset, trimmed, or extruded.
Projected geometry rules#
- Projected geometry is locked by default.
- If you create a sketch on an existing planar face, the edges of that face are projected into the sketch automatically.
- You can constrain your own geometry to projected geometry with Coincident, Tangent, dimensions, and so on.
- Projected geometry can be converted to construction geometry (Linetype in the Sketch Palette) so it does not create unwanted profiles (general practice).
- Show or hide it with Show Projected Geometries in the Sketch Palette.
- When the associative link is lost, a yellow warning appears on the sketch in the Timeline and the affected geometry is highlighted orange or yellow. Right-click the sketch in the Timeline and choose Manage Lost Projections, then select an item and an operation: Re-Link (select a new body, face, edge or point), Break Link (keep the geometry as non-associative), or Delete Geometry. The dialog also offers Fade Other Geometry, Delete All and Break Link All.
- A separate help video covers breaking the link so the projected curves can be modified independently.
Step by step: Intersect#
- Enter a sketch whose plane cuts through the model (an offset construction plane through a body, for instance).
- Choose Create > Project/Include > Intersect.
- In the dialog, choose the Selection Filter: Specified Entities (faces and edges to select) or Bodies. According to Autodesk, Specified Entities finds the intersection of points, lines, arcs and similar entities with the plane, while Bodies projects the entire intersecting profile of the selected body.
- Select the geometry (or the body), then click OK or press Enter.
- The cross-section outline or intersection points appear in your sketch.
Intersect is extremely useful for organic bodies and curved surfaces where drawing the section by hand would be difficult: place a plane through the area of interest, intersect the body, and you instantly have its cross-section for loft guides or follow-on features. Like Project, the result is typically associative.
Step by step: Include 3D Geometry#
Include 3D Geometry includes edges, work geometry, and sketch curves in the current sketch as 3D sketch geometry. Autodesk's tool page says you can select faces, edges, and points.
- Enter the sketch.
- Choose Create > Project/Include > Include 3D Geometry.
- Select the objects to include.
The tool has no further options. Contrast with Project, which projects onto the sketch plane; Include 3D Geometry brings the geometry in as 3D sketch geometry.
Note: not confirmed in Autodesk's documentation: that included curves behave as locked references and are never flattened. Check the result in your sketch.
Step by step: Project To Surface#
Project To Surface wraps sketch curves, edges, vertexes, or work points onto one or more faces.
- Create or choose the curves to project. Because the result lands in a new sketch, start a new sketch on any plane (or empty space) to contain it.
- Choose Create > Project/Include > Project To Surface.
- Select the face, surface feature or work plane to project onto.
- Select the objects to project (sketch geometry, edges, vertices or work points).
- Choose a Project Type: Closest Point (projects along the surface vector to the closest point on the faces) or Along Vector (projects along a selected vector).
- Click OK or press Enter. The result is a 3D sketch.
Use it to lay text or a logo outline onto a curved face, define a split line, or position features on a non-planar surface.
Step by step: Intersection Curve#
- Create the first sketch curve in one sketch.
- Choose Create > Project/Include > Intersection Curve in a different sketch (per Autodesk, the projected curve and the selected sketch curve cannot be in the same sketch).
- Select a sketch curve, then select the faces, surface features, work planes or curves to intersect on.
- Click OK or press Enter. A 3D sketch curve results where they meet.
Typical use: the intersection of two extruded sketch curves yields a 3D path, for example a pipe route defined by the plan view and the elevation view.
Options reference#
| Option | What it does | Notes/default |
|---|---|---|
| Selection Filter (Project) | Specified Entities (faces, edges, points) or Bodies | |
| Projection Link | Keeps projected geometry associative | Uncheck for non-associative geometry |
| Intersect: Specified Entities | Finds intersections of selected entities with the plane | Faces and edges to select |
| Intersect: Bodies | Entire intersecting profile of the body | Good for organic shapes |
| Include 3D Geometry | Includes edges, work geometry, sketch curves as 3D sketch geometry | No options |
| Project To Surface | Faces, Curves, Project Type (Closest Point / Along Vector) | Result lands in a new sketch |
| Intersection Curve | 3D curve from a sketch curve and faces or curves | Curves must be in different sketches |
| Manage Lost Projections | Re-Link, Break Link, Delete Geometry | Right-click the sketch in the Timeline |
| Show Projected Geometries | Visibility toggle | Sketch Palette |
Tips and pitfalls#
Tip: Project edges and points as construction geometry, and constrain your own sketch geometry to them. If the source moves, your sketch follows, and projected profiles don't produce unwanted extra regions.
Tip: To dimension from the origin in a sketch on a face, project the origin point into the sketch with the Project tool.
Tip: For a cross-section, put a construction plane through the body, sketch on it, and use Intersect with the Bodies filter.
Warning: Associativity is a double-edged sword. If a later change reorders or deletes the source geometry, projected curves in downstream sketches can fail and cascade failures. For parts that need to be robust, project from stable references (origin planes, sketches) and not from faces that might get replaced.
Warning: Projecting edges that lie parallel to the projection direction can yield points or collapsed lines (general behavior), which may seem like "nothing happened".
Warning: Projected curves overlay your own geometry; stacked duplicates can silently prevent profile creation. Hide or delete duplicates.
Practice exercise#
- Create a block (60 x 40 x 20 mm) and a sketch on its top face.
- Choose Create > Project/Include > Project (the sketch may already contain the face's edges, which project automatically when you sketch on a planar face), and make the projected edges construction.
- Draw a rectangle inset by 5 mm using Offset on the projected edges, or by constraining to them with 5 mm dimensions.
- Extrude the inset rectangle 3 mm up.
- Edit the original block's width to 80 mm and verify that the inset rectangle follows.
- Add an offset construction plane through the block middle, sketch on it, and use Intersect with Bodies to capture the cross-section.
Expected result: a raised pad that tracks the block outline, and a cross-section outline in the offset sketch.
Related#
- Constraints (02-sketching/constraints)
- Sketch best practices (02-sketching/sketch-best-practices)
- Troubleshooting sketches (02-sketching/troubleshooting)
- Sketch basics (02-sketching/sketch-basics)