Nick Armstrong-Crews

July 24, 2014

3D Sensing for 3D Printing:(because CAD is hard)

3D Printer Meetup - 2NAC 7/24/14

• Current: Roboticist, MIT Lincoln Laboratory– Focus: 3D perception

• Past: Carnegie Mellon Robotics Institute– Focus: Planning under uncertainty

• Future: Heuristic Labs– Focus: 3D sensors

• Origin (fun fact): Alaska– Focus: None

Who am I?

“Nick Armstrong-Crews” - http://www.linkedin.com/in/nickarmstrongcrews

3D Printer Meetup - 3NAC 7/24/14

• Theme: CAD is hard; a barrier to 3D printing revolution– Imagination ---(CAD)---> digital model ---(3D printing)---> Reality– Harder than 2D (i.e., photo-realistic painting/sketching)

• Aside: 2D sensing sucks– Loss of depth information; loss of absolute dimensions– Simply insufficient to aid creation in a 3D world

• Solution: 3D sensing to the rescue!

• Caveat: 3D sensing can be noisy– But fixing up a 3D model is easier than creating!

Why 3D Sensing is Important

“This stuff is really hard. It's hard to learn, hard to use, and mistakes have real consequences. This [is true] of any CAD or modeling software.”

“CAD is Hard” - http://sliptonic.com/cad-is-hard/

3D Printer Meetup - 4NAC 7/24/14

The “Matter Remixer”

“Reality Remixing” - http://bit.ly/MatterRemixerKS

3D Printer Meetup - 5NAC 7/24/14

• Principles:– Time-of-flight: ,– Stereo parallax (triangulation): ,– Multi-view stitching (mapping, SLAM): (complicated)

• Implementations:– Passive stereo vision: like humans! two cams, rigid mount, sparse and not robust

and reliant on background texture

– Structure-from-motion: monocular, move camera over time

– LIDAR: raster scanning/spinning point detector

– Active stereo vision: create own perfectly structured light

3D Sensing Techniques

𝒅=𝒄𝒕𝟐

“Time-of-Flight Camera – An Introduction” - http://www.ti.com/lit/wp/sloa190b/sloa190b.pdf“Triangulation (computer vision)” - http://en.wikipedia.org/wiki/Triangulation_(computer_vision) “Projected Texture Stereo” - http://www.willowgarage.com/sites/default/files/ptext.pdf“Serveo w/ Planar LIDAR” - http://april.eecs.umich.edu/magic/about/

𝒅=𝒃𝒇∆𝒖

𝒃

𝜺𝒅 𝒅𝟐

𝜺𝒅 𝜺𝒕

3D Printer Meetup - 6NAC 7/24/14

Available Hardware Comparison

“LazeeEye: Turn your Smartphone into a 3D Camera” - http://kck.st/1gVCcrB

Principle Cost Resolution Mobile? Outdoors? Caveats

DepthSense ToF $299 640x480, +-3cm at 3m

kinda

Kinect(Xbox One)

ToF $399 520x240 kinda Windoze 8.1

Xtion / Kinect (original)

ToF $99-$150 640x480, +-2cm at 2m

PrimeSense inside

Cubify Sense Active Stereo

$399 640x480, +-2cm at 2m

PrimeSense inside

Occipital Structure

Active Stereo

$379 640x480, +-2cm at 2m

Yes(tablet)

Apple-only, PrimeSense

inside

Google Project Tango

Active Stereo

$1024 640x480, +-2cm at 2m

Yes(tablet/phone)

Limited release, pre-production

HLLazeeEye

Active Stereo

$75 Yes(phone)

Yes Pre-production

3D Printer Meetup - 7NAC 7/24/14

• Structure-from-Motion– AutoDesk 123D Catch - http://www.123dapp.com/catch – VisualSfM - http://ccwu.me/vsfm – Seene iPhone App - http://seene.co

• DIY– DIY Structured Light - http://mesh.brown.edu/byo3d/source.html – DIY Stereo Cams - http://

wiki.ros.org/camera_calibration/Tutorials/StereoCalibration (any cam pair, but recommend PS4 Eye or dual PS3 Eyes)

• Computer-assisted 3D Editing– Meshlab - http://meshlab.sourceforge.net – AutoDesk Meshmixer - http://meshmixer.com

Useful Resources