In order to integrate seamlessly a virtual object in a real scene in augmented reality (AR) system, we need to simulate the
interactions of the virtual object with the illumination of the scene. Acquiring the knowledge of illuminant direction is
crucial in this work. We present a novel approach for estimating the direction from a single image of a scene that is
illuminated by a light source regardless it is point light source or directional one. We propose to employ a marker cube,
which is used to register to determine the rigid transformation relating 2D images to known 3D geometry, and a
Lambertian probe sphere, which is used to estimate the light source direction by image processing. The key process is
finding and extracting the intensity occluding curve on the sphere. Experimental results show that our approach is
computationally efficient and the light source direction can be accurately obtained by it.
KEYWORDS: Embedded systems, Autoregressive models, Digital signal processing, Image transmission, Data transmission, Augmented reality, Signal processing, Image processing, Telecommunications, LCDs
Network transmission is of great effect to capability of the desktop AR system, so speed and veracity of
network transmission is very important. This article introduces hardware and software design about the network
transmission system and experimental result shows that both speed and veracity of network transmission can
satisfy the requirement of image data transmission in desktop AR system.
The traditional tabletop AR systems general use head mounted display (HMD) that has some shortcomings, such as
the imprecise precision and low flexibility. To solve these problems, a new design of video see-through tabletop system
is presented. In this paper, we describe an outline of the system and the registration algorithms for the system. A system
origin calibration algorithm is proposed. In the calibration experiment, a sign cube is introduced for the first shooting of
the camera. The position of the sign cube becomes the origin of the world reference frame, in which the translation and
rotation of the virtual objects relative to the origin can be calculated easily. The experimental results show that the video
see-through tabletop system meets the precision and flexibility requirements very well.
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