Introduction: How to Trace an Image in SketchUp
Before I learned Rhino or CorelDraw, and definitely before I wanted to dish out money for Illustrator, there was SketchUp. I was a sophomore in college who just scratched the surface of learning about digital fabrication. I needed something free, versatile, and preferably with a support community. Enter SketchUp.
This tutorial is how to easily trace an image in SketchUp and export it to be laser cut, CNC cut, or even uploaded to a Cricut Die Cutter. I chose an image of the Kansas City skyline, although I only trace the iconic Power and Light Building.
Attached is a full-screen recording of my process to define future vector paths as well as step by step instructions.
Step 1: Image Inversion
For some reason, SketchUp's Paint Bucket Tool inverts an image when applied to a surface as a texture. So before I open SketchUp, I horizontally flip the image I want to trace in Photoshop CS5. This way the image will have the correct orientation once opened in SketchUp.
Step 2: Create Surface
My SketchUp workspace is set to use the Construction Documentation Template in Feet and Inches. The camera is set to top view.
Create a surface with desired dimensions. I drew a rectangle 6' x 4'.
Step 3: Select Paint Bucket Tool
After a surface is created, select the Paint Bucket Tool. A dialogue box will pop up. Select the Brick icon.
Step 4: Add Texture
To add a New Texture, double-click inside the box, and New Texture will appear as the only option in the drop-down menu. Select New Texture and select the saved inverted image. A new dialogue box will open listing dimensions, click OK.
Step 5: Adding Image to Surface
Click and select the image thumbnail then click the surface. The image will appear on the surface.
Step 6: Position Image
As you can see, the image has flipped back to its proper orientation. The image also becomes a tile pattern. To make the one image fill the entire surface, double-click the image and select Texture, then select Position.
Step 7: Scale
The primary image will now have little pins in each corner. Drag the bottom left hand (green) pin. This toggle proportionally scales and rotates the image. I enlarged the image until the Power & Light Building fit comfortably on the surface. Hit enter once you are finished and the image will restrain to the surface boundaries.
Step 8: Tracing With the Pencil Tool
Now select the Pencil tool and trace around the edges of the desired shape. When the shape is closed, you should be able to select it, bound by the new pencil lines.
Step 9: Clean Up the Shape
After the shape is closed, I clean up the image. Delete the extra lines around the shape as well as the bounding rectangle. Select and Delete to erase the surface. The Eraser tool can then be used to delete individual lines. This will help when the shape is more complex and lines tend to go in all directions.
Step 10: Way No. 1 to Prepare Shape for Fabrication
In this step, I use the Offset tool and move the outline past the shape. I then set the distance at 1/2", typed in the bottom, left of the screen. This is the best way if the image you are using is simple and rectilinear. In my personal work, the shapes I trace tend to be more complex and irregular. The Offset tool produces too many overlapping lines which become tedious to delete. The open line I deleted at the end of this clip could have become an unwanted vector path.
Step 11: Way No. 2 to Prepare Shape for Fabrication
In this step, I use the Tape Measure tool to manually create the offset lines. The Tape Measure tool permits the customization of line width. I then use the Pencil tool to trace the measured lines making sure to snap to line intersections.
Step 12: Delete Surface and Export
For the final step, delete the surface, so only lines remain. Next check to make sure there are no additional line segments, as they will transfer as unwanted cuts. Highlight what lines you wish to export.
Next, export the lines as a DXF file. Since I use the free version of SketchUp this feature is not available.
Instead, I downloaded a plugin linked here: http://sketchupplugins.com/plugins/convert-sketch...
Once, downloaded and installed, the plugin appears under the file menu.
Follow the prompts, export in the desired dimensions, save, and finished!
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