Dibyendu Nandy

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A novel generalized feature extraction method based on the expansion matching (EXM) method and on the Karhunen-Loeve transform (KLT) is presented. The method provides an efficient way to locate complex features of interest like corners and junctions with reduced number of filtering operations. The EXM method is used to design optimal detectors for a set of(More)
We explore a two-dimensional kinematic solar dynamo model in a full sphere, based on the helioseismically determined solar rotation profile and with an α effect concentrated near the solar surface, which captures the Babcock–Leighton idea that the poloidal field is created from the decay of tilted bipolar active regions. The meridional circulation, assumed(More)
Sunspots, dark magnetic regions occurring at low latitudes on the Sun's surface, are tracers of the magnetic field generated by the dynamo mechanism. Recent solar dynamo models, which use the helioseismically determined solar rotation, indicate that sunspots should form at high latitudes, contrary to observations. We present a dynamo model with the correct(More)
A novel method for representing 3-D objects that uniies viewer and model centered object representations is presented. A uniied 3-D frequency-domain representation (called Volumetric Frequency Representation-VFR) encapsulates both the spatial structure of the object and a continuum of its views in the same data structure. The frequency-domain image of an(More)
In this paper, we develop a novel framework for robust recovery of three-dimensional (3-D) surfaces of faces from single images. The underlying principle is shape from recognition, i.e., the idea that pre-recognizing face parts can constrain the space of possible solutions to the image irradiance equation, thus allowing robust recovery of the 3-D structure(More)
In this paper, a novel framework for the recovery of 3D surfaces of faces from single images is developed. The underlying principle is shape from recognition, i.e. the idea that pre-recognizing face parts can constrain the space of possible solutions to the image irradiance equation, thus allowing robust recovery of the 3D structure of a specific part.(More)
A novel method for extracting parametric junction and corner features in images is presented. By treating each complex feature as a combination of elementary line and edge features, the method provides an efficient way to locate features of interest with reduced number of filtering operations. The Expansion Matching (EXM) method is used to design optimal(More)
Sunspots appear on the Sun in two bands on either side of the equator that drift toward lower latitudes as each sunspot cycle progresses. We examine the drift of the centroid of the sunspot area toward the equator in each hemisphere from 1874 to 2002 and find that the drift rate slows as the centroid approaches the equator. We compare the drift rate at(More)
In this work, a framework for the reconstruction of smooth surface shapes from shading images is presented. The method is based on using a backpropagation based neu-ral network for learning brightness patterns and associating them with range data. The network is designed to reconstruct surface range from localized intensity patches of 77 pixels. Two methods(More)