3D Scanning Basics

by Daniel Tankersley

Use the online reservation system to schedule a time for your 3D scan. You may operate the scanner only under supervision of Fab Lab staff.

Cover your object in positioning targets (dots). They should be spaced randomly, about 1 to 3 inches apart. You need to be able to see at least 4 dots from every possible angle of view. If the object is too small to be covered in dots, you may opt to place it on a dot-covered surface instead. You will remove unwanted data later.

Plug in the power cords of the laptop and scanner. Insert the FireWire Dual-Port Cardbus into the slot on the side of the laptop. Connect the scanner via Firewire.

Turn on the laptop. Open the Launch ZScan application.

Go to Configure > Sensor Configuration. Click Auto, wait until it’s ready, aim the scanner at your object (about a foot away), and hold down the trigger. When the colored bar rests between the middle brackets (in the Reliable range), let go of the trigger, click Apply, and click OK.

Click the small triangle next to Scan Surface and choose Scan Positioning Features. Click Record Scan. Hold down the trigger and slowly scan the object until all positioning features (dots) have registered. If you move too quickly, the dots may be recorded twice or in the wrong position. If this happens, you must start over (Reset Scan). When all dots are registered, click Stop Scan.

Go to File > Save Session. Remember to continue saving your session throughout the scanning process. It’s a good idea to use your name in the filename, and to save multiple iterations (e.g. Tank01, Tank02, etc) rather than writing over the same file again and again. You can also go to File > Save Positioning Features to save a file of just the dot positions, in case you need to start over later.

Click the small triangle next to Scan Positioning Features. Choose Scan Surface. Click Record Scan. You are now scanning the object’s surface. Hold down the trigger and move very slowly. Use the red beams (crosshairs) to aim. You can let go of the trigger as often as you want. When pressing the trigger again, make sure to start with an area the scanner has already recognized. The scanner should be about 12 inches from the object at all times. Watch the laptop monitor AND your object at the same time (tricky but you’ll get used to it). Keep the distance-tracking bar in the green zone for best results (not too close nor too far). Be very careful not to move too quickly. If the dots begin to float, multiply, or move separately from the surface, this is a problem. You may need to add more dots or start over.

When you have roughed out the form of the object, click Stop Scan. In the left column of ZScan, click Surface. In the options below that, click Fit Volume. You can also fine-tune the size and placement of the bounding box with these options. Click Apply.

Click Record Scan and slowly scan until the object is completely filled in (or as close as possible). Click Stop Scan. Save your session.

Go to File > Save Facets to save your scan as an STL file.

Open the Rapidform XOR2 application (red icon). Go to Insert > Import. Choose your STL file.

In the left column of Rapidform, click the name of your imported file. Click the Mesh button near the top left of the screen to enter mesh mode.

Delete unwanted data using the different selection tools at the bottom left of the screen and the delete key. One good method is to use the paint bucket (flood fill selection) on the main part of your scan -- what you want to keep -- then go to Select > Inverse, then hit delete.

Go to Tools > Mesh Tools > Rewrap. This function allows you to fill all the holes in your mesh at once. Try playing with the options for best results. Click the check mark button to finalize the rewrap.

You can also use Tools > Mesh Tools > Fill Holes to fill individual holes without rewrapping the entire mesh.

When you are finished fixing the model, click the Mesh button again to exit mesh mode. Go to File > Export. Make sure your mesh is selected. Choose STL as the file type.