Archive for the ‘Electronics’ Category

Hardware design tools for the web – Upverter

November 18, 2011 Leave a comment

Social Making: Hardware design tools for the web – Upverter.

It’s like github for open source hardware


Why the Arduino Won and Why It’s Here to Stay

Make: Online | Why the Arduino Won and Why It’s Here to Stay.

Really nice article explaining some of the reasons for the Arduino Success. One of the most important reasons is, IMHO, its open source hardware/software approach.

Android Adds USB Host + Audio, Open Hardware ADK with Arduino; Good News for Mobile Music

Laser Harp Project

February 21, 2011 Leave a comment

This Laser Harp 2010 project is the inspiration for a project at FEUP I’m currently co-advising (more news on that soon).

Some pointers related to this:

What the Kinect sensor actually does…

February 21, 2011 Leave a comment

What the Kinect sensor actually does…

Interesting post on how the MS Kinect may actually work.

Some (unofficial and still to be confirmed) specs summarized from the post linked above (and comments):

  • the Kinect appears to be a 640×480 30fps video camera that knows the *depth* of every single pixel in the frame. It does this by projecting a pattern of dots with a near infrared laser over the scene and using a detector that establishes the parallax shift of the dot pattern for each pixel in the detector (parallax seems to be more robust than intensity – some sources said that materials ( hair in particular ) caused large fluctuations in intensity, so it doesn’t seem like it would be a useful channel to probe for depth data).
  • The depth buffer is only 320×480 (unconfirmed). It seems that the hardware will happily give a 640×480 version (this is Xbox360 API memory, so upscalingmay actually occur on the XBox360) but the hardware itself only gets enough data to fill 320×480.
  • Alongside this there is a regular RGB video camera that detects a standard video frame. This RGBZ (or ‘D’) data is then packaged up and sent to the host over USB.
  • It seems that the Kinect framerate (for RGB image and depth buffer) is 30Hz.
  • The Kinect does not identify shapes within the field of view and does not attempt to map skeletal outlines of those shapes recognised. For that, you would need to take each one of the 640×480 frames and copy them into a framebuffer so they can be processed by a vision library like OpenCV. Typical operations would be to threshold the depth image to get the “closest” pixels – then perform a blob analysis ROI to group these pixels into identifiable features and then track those blobs over their lifetime.
  • The Kinect uses a pattern of laser dots to detect depth, as can be seen in this video (and another one, and another one, and another one ;-)) and in these images. It seems to exist a 3×3 checker board effect in that dot pattern (no clue why yet… any suggestions?).

So, processing all this data seems to be quite heavy (mainly if you try to do it in an embedded board like the guy from the post above). Using a full-fledged PC/Mac using openCV and/or OpenCL in a multicore machine will get you the required juice for advanced image processing.

Finally, some quite interesting resources for Kinect related stuff:

Arduino Tutorials

February 10, 2011 Leave a comment

More than 20 chapters of Arduino Tutorials « t r o n i x s t u f f.

Project HiJack uses iPhone audio jack to make cheap sensors

January 18, 2011 Leave a comment
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