Constellation Model


The constellation model is a probabilistic, generative model for category-level object recognition in computer vision. Like other part-based models, the constellation model attempts to represent an object class by a set of N parts under mutual geometric constraints. Because it considers the geometric relationship between different parts, the constellation model differs significantly from appearance-only, or "bag-of-words" representation models, which explicitly disregard the location of image features.

The problem of defining a generative model for object recognition is difficult. The task becomes significantly complicated by factors such as background clutter, occlusion, and variations in viewpoint, illumination, and scale. Ideally, we would like the particular representation we choose to be robust to as many of these factors as possible.

In category-level recognition, the problem is even more challenging because of the fundamental problem of intra-class variation. Even if two objects belong to the same visual category, their appearances may be significantly different. However, for structured objects such as cars, bicycles, and people, separate instances of objects from the same category are subject to similar geometric constraints. For this reason, particular parts of an object such as the headlights or tires of a car still have consistent appearances and relative positions. The Constellation Model takes advantage of this fact by explicitly modeling the relative location, relative scale, and appearance of these parts for a particular object category. Model parameters are estimated using an unsupervised learning algorithm, meaning that the visual concept of an object class can be extracted from an unlabeled set of training images, even if that set contains "junk" images or instances of objects from multiple categories. It can also account for the absence of model parts due to appearance variability, occlusion, clutter, or detector error.

Read more about Constellation ModelHistory, The Method of Weber and Welling Et Al., The Method of Fergus Et Al., Performance, Variations

Other articles related to "constellation model, model, constellation models, models":

Constellation Model - Variations
... One variation that attempts to reduce complexity is the star model proposed by Fergus et al ... The reduced dependencies of this model allows for learning in time instead of ... This allows for a greater number of model parts and image features to be used in training ...
One-shot Learning - Theory - Object Category Model
... For each query image and training images, a constellation model is used for representation ... To obtain this model for a given image, first a set of N interesting regions is detected in the image using the Kadir brady saliency detector ... training images, the expression for R becomes The likelihoods and are represented as mixtures of constellation models ...
Part-based Models
... Part based models refers to a broad class of detection algorithms used on images, in which various parts of the image are used separately in order to ... these methods a very popular one is the constellation model which refers to those schemes which seek to detect a small number of features and their ... These models build on the original idea of Fischler and Elschlager of using the relative position of a few template matches and evolve in complexity in the work of Perona and others ...

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