PTAM Revealed

ptam_screenshotPTAM (Parallel Tracking & Mapping) is a robust visual SLAM approach developed by Dr. George Klein at Oxford University. It tracks the 3D pose of the camera quite rapidly at frame rate which in turn becomes an ideal platform for implementing marker-less augmented reality. Through this post I’m going to reveal my own insights about PTAM with the help of my hands-on experience with it.

PTAM runs tracking & mapping in two separate threads. Inside the PTAM implementation we can find two files namely, Tracker.cc & MapMaker.cc (NOT the MapViewer.cc). Before start tracking, it demands an initial map of the environment and it was being built by the tracker.  In System.cc there’s function called Run (). The tracking thread runs in this function. In order to build the initial map, user should supply a stereo image pair, particularly on a planar surface. PTAM calculates the initial pose with Homography Matrix, whereas the 3D coordinates of the initial map points were generated with Triangulation. Then the tracker grabs each frame in a tight loop and calculates the camera pose. The tracker performs the pose calculation in following manner. This was implemented inside the TrackFrame() function (Tracker.cc).  Continue reading “PTAM Revealed”

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Compiling ARToolkit on Ubuntu 10.04

Apparently I’ve given more thought on to ARToolkit these days  (mainly due to my research), so that it makes me  attempt different things with it. Consequently I’ll be writing a series of posts pertaining to my small experiments for future references. I know it’s pretty boring stuff, talking about a dull subject again and again… but it merely gives us a sensation when doing it physically (particularly when you have nothing left to do 😉 ). In general everybody feels great when their imaginations turn into a physical realization.

ARApplicationInUbuntu

So… enough lecturing & let me keep aside my talking. In today’s post I’ll cover-up the installation of ARToolkit in Ubuntu 10.04. Continue reading “Compiling ARToolkit on Ubuntu 10.04”

Demistifying DSVL Configuration

directx-logoIn my previous post I just mentioned how we can use ARToolkit in conjunction with a 3D rendering engine. The camera connection was made by the ARToolkit via DSVL (DirectShow Video Library) . As I promised, through this post, I’ll expose how we can configure DSVL with its supported parameters.

DSVL is a wrapper for DirectShow which in turn is a part of DirectX. We all know that DirectX is the prominent media framework used in windows platforms. Other than DirectShow, Direct3D and DirectSound also come under the brotherhood of DirectX. So what is the specialty of DirectShow? In computers data can be generated in many places, such as file system, network, TV cards or video cameras etc. And data which is produced at each of these locations take many formats. Therefore front-end applications have to explicitly communicate with these underlying data sources and deal with its formats. Obviously this would be pretty cumbersome and overwhelmingly incompatible with different hardware devices. This is where DirectShow comes in to handy. It synchronizes and unifies all the communication flow between our application and the underlying hardware. In particular DirectShow talks directly with the camera drivers, capture card drivers etc… and provide feedback for the user application. This is the simplest way we can understand it, but for more details go here http://msdn.microsoft.com/en-us/library/windows/desktop/dd375454(v=vs.85).aspx .

Continue reading “Demistifying DSVL Configuration”

Combining ARToolkit & OGRE

AR and OGRE

It’s wonderful to see AR Applications, running within our physical environment. For an average guy it really looks like magic. But creating that magic was never easy. A professional magician always has to acquire a proven set of tools and techniques in order to deliver a realistic illusion. So as with the developer! For years ARToolkit served as the fundamental set of software package for crafting AR applications. However it becomes more rewarding to combine ARToolkit with a 3D Graphics Rendering Engine so that a one can create his own 3D graphics or even an animation and turn them into Augmented Reality. Therefore the objective of this article is to share my own experience in combing an AR application with a 3D rendering engine.

Continue reading “Combining ARToolkit & OGRE”

Nature – Is it Just a Coincidence?

It seems to be quite a coincidence how things happen in nature. For instance blooming flowers, reproduction of species, waveforms in the sea appears to be random and chaotic.  There’s no one behind driving these forces. It’s driven by the nature itself. However further insights into these chaotic motions of nature, reveals something unbelievable. That is, things happen in nature according to a pattern.

Obviously nature organizes things in the most effective and easiest manner. Large formations are constructed by combining smaller parts. Yet these large formations are similar in shape to the smaller components. The fern leaf is the best example. The whole fern leaf was formed as a result of recursive placement of smaller leaflets. This phenomenon is known as Fractals – self similar patterns. Self-similar patterns can be seen everywhere. Rock formations, growth pattern of a leaf, surface of broccoli & Cauliflower, Fractal Mountains, lightning, and even clouds express this nature. The growth pattern of fractals are predictable, they are not just random. The following describes how. Continue reading “Nature – Is it Just a Coincidence?”

Turing Machines – A Review

It’s known that the Turing machine was the first theoretical model of modern day computers. But it’ll be a fruitful effort to find out why? The fascinating thing was it’s still capable of computing most of the existing computer operations including basic arithmetic (addition, subtraction, etc…) into much complex algorithms. Therefore it’s worth digging down deep into this idea and see how it relates to (or how it does) computer operations.

The bare roots of Turing Machines go back into the theory of computation. During the early decades of 1900’s there’s been an increasing demand for a machine capable of computing. Obviously this was a part of several military projects run by allied groups for gaining victory over the war. So that, this signifies the necessity for defining the science behind computing. Generally, the computational theory consists of three parts.

Continue reading “Turing Machines – A Review”

Remote Human-Robot Operations with Adjustable Autonomy

CuriosityThis article was based on the work carried out by [1]. In future NASA’s space missions will include more and more interactive robots. The Curiosity rover that has been recently sent to Mars was a good example for that. These kinds of robots require new remote operation mechanisms for effective use. In such a tele-operated context, a human team should constantly supervise the robot and manually perform tasks whenever needed.

An important aspect of such operations is the ability to allocate tasks between humans and robots effectively. This capability was known as Adjustable Autonomy (Adaptive Autonomy) so that the automation can be smart enough to achieve the autonomy required according to changing situations. Human-robot interactions are closely related to adjustable autonomy, and they both go side-by-side. Apparently, human robot operations are highly dependent upon the scenario so that they become specific to a given robot, thus making it hard to generalize them. Given below is a sub-set of such human robot operations. Continue reading “Remote Human-Robot Operations with Adjustable Autonomy”