MixFab: a mixed-reality environment for personal fabrication
Christian Weichel, Manfred Lau, David Kim, Nicolas Villar, Hans Gellersen
Personal fabrication machines, such as 3D printers and laser cutters, are becoming increasingly ubiquitous. However, designing objects for fabrication still requires 3D modeling skills, thereby rendering such technologies inaccessible to a wide user-group. MixFab is a new mixed-reality environment for personal fabrication that lowers the barrier for users to engage in personal fabrication. Users design objects in an immersive augmented reality environment, interact with virtual objects in a direct gestural manner and can introduce existing physical objects effortlessly into their designs.

Mixed Reality

MixFab provides an immersive, mixed-reality environment where virtual and physical objects coexist. Figure a shows a user placing an existing physical object into a virtual one, which interacts with the phsyical entity by occluding it. Even though one object is virtual, the other one a physical entity, both objects share the same space.

Existing objects can be scanned in place to make them virtual ones; either instanntenously with limited precision, or more detailed usin a 3D scanning process within a minute. This integrated transition of physical to virtal objects further blurs the line between virtual and physical objects.

Virtual objects in MixFab can be manipulated as if they were physical entities. They can be grabbed, moved around and rotated much like one would in the real world.

Example Walkthrough: a desktop organizer

 

We start with creating the base shape by drawing a circular outline. The system recognizes the drawing as a circle, beautifies it and offers the outline for extrusion. We set the height using one hand; the height snaps to 5mm increments and is displayed just above the object. To confirm the height, we tap with the other hand.

To create the semi-rectangular shape of the organizer, we cut off both sides. First we cut off the right side of the object by indicating the cut position with the right hand and confirming with the left. To cut the left side, we repeat the procedure, this time holding the left hand where we want to cut and confirming with the right one.

Next, we create the first hole which will hold the glue-stick. We position the real glue-stick where we want the hole to be within the virtual object. Once in position, we select "capture outline" and move our hands out of the frame. The system then captures the outline of the glue-stick and extrudes its height. Confirming that initial height with the left hand, turns it into a virtual glue-stick replica. As the glue-stick was standing on the ground of the frame, the virtual glue-stick replica is on the ground as well. If we were to assemble the object as it is, we would create a hole through the whole shape. To have some material at the bottom of the hole, we grab the virtual glue-stick, move it a few millimeters up and release it to fix it in that position. Eventually we assemble the virtual glue-stick and the previously created base to create the hole for the stick. After selecting assembly, we are asked to choose the method of assembly. Choosing subtract removes material where the glue-stick was, leaving a hole of correct size and position.

Lastly we repeat the steps above for the pen, placing it in its desired position, capturing its outline, extruding it and moving it up a few millimeters. To make the pen easier to access, we tilt it forward by grabbing at a point in space, forming a lever with which the object is re-oriented. Once in correct position and orientation, we assemble the virtual pen replica resulting in the final desktop organizer.

Things designed with MixFab

We designed a few objects with Mixfab; a set that is by no means exhaustive but only shows what it can be used for. All of these objects interact with a previously existing artefact, such as a pen, toy car or mobile phone. During the design of e.g., the phone dock, the phone itself was used to create a slot of the right size.

We have uploaded the phone dock and desk organizer on Thingiverse. So should you have a Nexus 4, or the depicted stationary items, feel free to print or remix them.

Publication

Christian Weichel, Manfred Lau, David Kim, Nicolas Villar and Hans Gellersen. 2014.
MixFab: A Mixed-Reality Environment for Personal Fabrication.
In Proceedings of CHI '14 (to appear).


Download high-resolution pictures here.