More Than Technical – Page 14 – Code, content, and more.

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Quick and Easy Head Pose Estimation with OpenCV [w/ code]

Post author By Roy
Post date March 19, 2010
30 Comments on Quick and Easy Head Pose Estimation with OpenCV [w/ code]

Update: check out my new post about this https://www.morethantechnical.com/2012/10/17/head-pose-estimation-with-opencv-opengl-revisited-w-code/
Hi
Just wanted to share a small thing I did with OpenCV – Head Pose Estimation (sometimes known as Gaze Direction Estimation). Many people try to achieve this and there are a ton of papers covering it, including a recent overview of almost all known methods.
I implemented a very quick & dirty solution based on OpenCV’s internal methods that produced surprising results (I expected it to fail), so I decided to share. It is based on 3D-2D point correspondence and then fitting of the points to the 3D model. OpenCV provides a magical method – solvePnP – that does this, given some calibration parameters that I completely disregarded.
Here’s how it’s done

Tags 3d, augmented reality, computer vision, head pose, opencv, opengl

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Implementing PTAM: stereo, tracking and pose estimation for AR with OpenCV [w/ code]

Post author By Roy
Post date March 6, 2010
23 Comments on Implementing PTAM: stereo, tracking and pose estimation for AR with OpenCV [w/ code]

Hi
Been working hard at a project for school the past month, implementing one of the more interesting works I’ve seen in the AR arena: Parallel Tracking and Mapping (PTAM) [PDF]. This is a work by George Klein [homepage] and David Murray from Oxford university, presented in ISMAR 2007.
When I first saw it on youtube [link] I immediately saw the immense potential – mobile markerless augmented reality. I thought I should get to know this work a bit more closely, so I chose to implement it as a part of advanced computer vision course, given by Dr. Lior Wolf [link] at TAU.
The work is very extensive, and clearly is a result of deep research in the field, so I set to achieve a few selected features: Stereo initialization, Tracking, and small map upkeeping. I chose not to implement relocalization and full map handling.
This post is kind of a tutorial for 3D reconstruction with OpenCV 2.0. I will show practical use of the functions in cvtriangulation.cpp, which are not documented and in fact incomplete. Furthermore I’ll show how to easily combine OpenCV and OpenGL for 3D augmentations, a thing which is only briefly described in the docs or online.
Here are the step I took and things I learned in the process of implementing the work.
Update: A nice patch by yazor fixes the video mismatching – thanks! and also a nice application by Zentium called “iKat” is doing some kick-ass mobile markerless augmented reality.

Tags 3d, augmented reality, code, opencv, opengl, sfm

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iPhone OS 3.x Raw data of camera frames

Post author By Roy
Post date February 27, 2010
1 Comment on iPhone OS 3.x Raw data of camera frames

Hi All
It looks like it’s finally here – a way to grab the raw data of the camera frames on the iPhone OS 3.x.
Update: Apple officially supports this in iOS 4.x using AVFoundation, here’s sample code from Apple developer.
A gifted hacker named John DeWeese was nice enough to comment on a post from May 09′ with his method of hacking the APIs to get the frames. Though cumbersome, it looks like it should work, but I haven’t tried it yet. I promise to try it soon and share my results.
Way to go John!
Some code would be awesome…
Roy.

Tags frame grabbing, iphone, video

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SmartHome – Embedded computing course project

Post author By Roy
Post date February 21, 2010
1 Comment on SmartHome – Embedded computing course project

Hi
In the past few weeks I have been working hard at a few projects for end-of-term at Uni. One of the projects is what I called “SmartHome”, for Embedded computing [link] course, is a home monitoring [link] application. In the course the students were given an LPC2148 arm7-MCU (NXP) based education board, implemented by Embedded Artists [link]. My partner Gil and I decided to work with ZigBee extension modules [link] to enable remote communication.
Here are the steps we took to bring this project to life.

Tags arm, embedded, java, school, swt, zigbee

Solutions Stream work

Stream your favorite radio station to your workplace

Post author By arnons
Post date January 29, 2010
1 Comment on Stream your favorite radio station to your workplace

I want to suggest a trick that worked for me. My work place blocks most of the popular radio stations stream sites in my country.
I can understand why they’re doing that, but hey – if you want to save bandwidth I suggest you block YouTube (not that I complain…)
Well, I thought of a way to listen to my favorite radio station from work, by re-streaming it from my home. And it worked!

It can also work for you, in case your IT does not block by protocol, only by address.

So here’s how to do it:

Tags block, bypass, corporate, re-stream, Stream, vlc, worksplace

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Recoloring via Histogram Matching with OpenCV [w/ code]

Post author By Roy
Post date January 28, 2010
16 Comments on Recoloring via Histogram Matching with OpenCV [w/ code]

Hi
I wanted to do the simplest recoloring/color-transfer I could find – and the internet is just a bust. Nothing free, good and usable available online… So I implemented the simplest color transfer algorithm in the wolrd – Histogram Matching.
Here’s the implementation with OpenCV