How to trace around a reference image in Fusion
- Brad Tallis
- Jan 16
- 5 min read
Do you want to organize your tool chest with custom foam cutouts? One of the best ways to get a perfect fit is to trace your actual tools using Fusion. This process lets you take a photo of an object, bring it into your design software, and create a precise outline for a laser cutter or CNC machine. While it might seem as simple as drawing lines over a picture, there are specific tricks you need to know to get the sizing and shapes exactly right.
Start with a Great Photo
The most important part of tracing starts before you even open Fusion. If your photo is bad, your digital model will be wrong. You need to avoid a problem called parallax.
Understanding Parallax
Parallax happens when you are too close to an object. This makes vertical walls look angled. In Fusion, this will make your trace inaccurate because you cannot see the true footprint of the tool.
To fix this, follow these steps:
Move the camera as far away from the tool as possible.
Use your camera’s zoom to get a close-up view of the object.
Keep the camera lens directly over the center of the object.
By standing back and zooming in, the light rays hitting the camera lens become more vertical. This gives you a flat, "top-down" view that is much easier to trace.
Lighting and Focus
Good lighting is another key factor. You want sharp, crisp edges so you can see exactly where the tool ends. Try to avoid heavy shadows, as they can hide the true shape of the object. Make sure the entire object is in focus. If the edges are blurry, your trace will just be a guess.
Pro Tip: Place a ruler or a scale next to your tool in the photo. This makes the next steps in Fusion much faster and more accurate.
Bringing Your Image into Fusion
Once you have your photo, it is time to bring it into Fusion as a Canvas. Go to the Insert menu and select Canvas. Choose your image and pick the plane where you want to place it.
Fixing the Aspect Ratio
Sometimes, your image might look squished or stretched when you first import it. This often happens with photos taken with a camera in portrait mode. Fusion might try to fit a tall portrait image into a wide landscape box.
To fix a squished image:
Go to the image file on your computer.
Right-click the image.
Select Rotate Left or Rotate Right.
Save the change and re-insert the image into Fusion.
Rotating the file before importing it ensures the aspect ratio stays correct.
Calibrating for Real-World Size
Your photo does not have any size data when it first enters Fusion. A stapler might appear as small as a stamp or as large as a car. You must calibrate the canvas to make it the correct size.
In the Browser tree on the left, find the Canvases folder.
Right-click on your image and select Calibrate.
Click two points on the image that you can measure in real life.
Type in the actual distance between those two points.
For the best results, pick points that are as far apart as possible. If you measure a tiny 10mm gap, a small error will grow across the whole tool. If you measure the entire length of a 150mm stapler, your scale will be much more accurate.
Aligning Your Canvas
It is hard to draw straight lines if your photo is sitting at a weird angle. Before you start sketching, turn on your Layout Grid.
Right-click your canvas and select Edit Canvas. Use the rotation handle to line up a straight edge of your tool with the grid lines on the screen. You can also drag the image so a specific corner sits at the 0,0 origin point. This makes the rest of your design work much cleaner.
Smart Tracing Techniques
Many people start tracing by using the Spline tool and clicking dozens of points. Too many points make your sketch hard to change later and is difficult to manage.
Use Arcs and Lines First
The best way to trace is to keep it simple. Most tools are made of basic shapes like straight lines and arcs or circles.
Use the Three-Point Arc for curved edges.
Use the Line tool for straight sections.
Only use Splines for very complex, organic shapes.
When using arcs, place the first two points at the ends of the curve. Use the third point to match the curve of the tool. If the arc doesn't fit perfectly, you can drag the center point to adjust it.
Adding Constraints
Constraints are the "rules" of your sketch. Even when tracing a photo, you should use them. This will make cutting out the profile look nicer and smoother.
Tangency: If a straight line meets a curve, add a Tangent constraint. This makes the transition smooth.
Horizontal and Vertical: Use these for edges that should be perfectly straight.
Coincident: Use this to make sure your lines and arcs are actually touching at the corners.
The Extend and Fillet Trick
A great way to get sharp corners into smooth curves is the "Extend and Fillet" method.
Draw two straight lines that follow the edges of your object.
Have them stop short of each other.
Use the Extend tool to make them meet at a sharp point.
Use the Fillet tool to add a curve to that sharp corner.
This gives you a much more professional result than trying to freehand an arc between two lines.
Mastering the Spline Tool
If you must use a spline for a finger hole or a handle, use as few points as possible. You can often trace a complex hole with just four points instead of fourteen.
Once you place a spline, click on the points to see the green tangency handles. You can pull these handles to change the "weight" of the curve. You can also rotate the handles to change the direction of the curve.
If you find that you truly need more detail, right-click the spline and select Insert Spline Point. This lets you add more control exactly where you need it without cluttering the rest of the shape.
Final Steps for a Perfect Cutout
After you finish tracing the outline, turn the canvas off. This helps you see if there are any gaps in your lines. If the profile doesn't turn blue (or show a closed shape), you have a gap that needs to be closed.
Adding Clearance
If you are cutting foam, you don't want the hole to be the exact size of the tool. It would be too hard to get the tool in and out. Use the Offset tool to create a small gap.
Select your entire trace.
Set an offset to the distance you want.
This creates a slightly larger hole so your tool fits comfortably.
Check Out Automated Tools
If you have a lot of tools to trace, you might want to look at AI options. A site called ToolTrace.ai can take your photos and turn them into outlines automatically. This can save you a lot of time if you are organizing a massive tool chest.
Conclusion
Tracing a physical object in Fusion is a powerful skill for any maker. By avoiding parallax in your photos and using simple arcs and lines instead of complex splines, you can create professional designs. Remember to calibrate your image using the longest measurement possible to ensure your tool fits the first time you cut your foam.
Once you master these steps, you can move beyond tool chests. You can use these same tricks to create custom cases for electronics, reverse engineer objects, or replacement parts for broken items around the house.
Comments