Using Photogrammetry To Design 3D Printed Parts

[Stefan] is building a fixed wing drone, and with that comes the need for special mounts and adapters for a GoPro. The usual way of creating an adapter is pulling out a ruler, caliper, measuring everything, making a 3D model, and sending it off to a 3D printer. Instead of doing things the usual way, [Stefan] is using photogrammetric 3D reconstruction to build a camera adapter that fits perfectly in his plane and holds a camera securely.

ScanPhotogrammetry requires taking a few dozen pictures with a camera, using software to turn these 2D images into a 3D model, and building the new part from that model. The software [Stefan] is using is Pix4D, a piece of software that is coincidentally used to create large-scale 3D models from drone footage.

With the 2D images turned into a 3D model, [Stefan] imported the .obj file into MeshLab where the model could be cropped, smoothed, and the file size reduced. From there, creating the adapter was as simple as a little bit of OpenSCAD and sending the adapter model off to a 3D printer.

Just last week we saw photogrammetry used in another 3D object scanner. The results from both of these projects show real promise for modeling, especially with objects that are difficult to measure by hand.

Rigging Your 3D Models In The Real-World

Computer animation is a task both delicate and tedious, requiring the manipulation of a computer model into a series of poses over time saved as keyframes, further refined by adjusting how the computer interpolates between each frame. You need a rig (a kind of digital skeleton) to accurately control that model, and researcher [Alec Jacobson] and his team have developed a hands-on alternative to pushing pixels around.

3D Rig with Control Curves
Control curves (the blue circles) allow for easier character manipulation.

The skeletal systems of computer animated characters consists of kinematic chains—joints that sprout from a root node out to the smallest extremity. Manipulating those joints usually requires the addition of easy-to-select control curves, which simplify the way joints rotate down the chain. Control curves do some behind-the-curtain math that allows the animator to move a character by grabbing a natural end-node, such as a hand or a foot. Lifting a character’s foot to place it on chair requires manipulating one control curve: grab foot control, move foot. Without these curves, an animator’s work is usually tripled: she has to first rotate the joint where the leg meets the hip, sticking the leg straight out, then rotate the knee back down, then rotate the ankle. A nightmare.

[Alec] and his team’s unique alternative is a system of interchangeable, 3D-printed mechanical pieces used to drive an on-screen character. The effect is that of digital puppetry, but with an eye toward precision. Their device consists of a central controller, joints, splitters, extensions, and endcaps. Joints connected to the controller appear in the 3D environment in real-time as they are assembled, and differences between the real-world rig and the model’s proportions can be adjusted in the software or through plastic extension pieces.

The plastic joints spin in all 3 directions (X,Y,Z), and record measurements via embedded Hall sensors and permanent magnets. Check out the accompanying article here (PDF) for specifics on the articulation device, then hang around after the break for a demonstration video.

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MAME cabinet 3D modeled and CNC milled

[Entropia] is just putting the final touches on his bar-top MAME cabinet (translated). The project started out as a 3D model to get the case dimensions just right. An old laptop is being, so the enclosure was designed to fit the bare LCD assembly and hide the rest of the computer. [Entropia] had access to a CNC mill through an education program and used it to cut most of the parts for the case out of MDF.

From there the build proceeds as normal. Mounting holes for the controls were cut with a drill and hole saws. We think it’s a bit easier to lay this design out once you have the control panel itself milled, rather than try to get it right in the 3D model. The image above is part way through the build. Since it was taken the case has been painted and a sound system was added but it looks like it’s still waiting for a bezel over the LCD and a marquee for the masthead.

You can see a demo of the game selection UI after the break.

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Laser cut 3D sculptures remind us of an old Playstation

[Paul] a.k.a. [VoidFraction] put up the source and documentation for his sculptures made with laser cut polygons.

For computing his triangles, [Paul] developed LcAgl, an algorithm that transforms a 3D model into the AutoCAD file needed to cut a whole bunch of triangles and connectors. This file was shot over to a laser cutter and after a confusing assembly, [Paul] can make just about any low polygon count model he wants.

For his sculptures, [Paul] uses Coroplast, a type of corrugated plastic commonly used in political campaign signs. Coroplast is lightweight and flexible, a bonus when [Paul] is fitting his triangles together. The connecting tabs are made from acrylic – a very rigid material, so the triangles are held tightly in place.

Since the models in most 3D games are just a bunch of polygons anyway, this technique reminds us of the first 3D console games. [Paul]’s rhino looks like it walked off the set of a low polygon game like Virtua Fighter or Jumping Flash!.

MINI’s augmented reality ad


We were surprised last month when we saw augmented reality being done completely in flash. It hasn’t taken too long to go mainstream though. MINI has incorporated it into a recent German language magazine ad campaign. The fiduciary marks actually work quite well with MINI’s established ad format. Visit the ad’s URL and hold the magazine up to the webcam and a 3D model of the MINI Cabrio will appear. They have a PDF of the ad that you can print and use if you don’t have the original. Unfortunately, it doesn’t seem to have cross-platform support.

[via Autoblog]