Package pyvision :: Package surveillance :: Module BackgroundSubtraction :: Class MotionCompensatedFrameDifferencer

Class MotionCompensatedFrameDifferencer

AbstractBGModel --+
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                 MotionCompensatedFrameDifferencer

This class represents a more sophisticated frame differencing algorithm that takes into account potential camera motion, and applies a registration method to align subsequent images prior to frame subtraction.

Instance Methods

[hide private]

__init__(self, imageBuffer, thresh=20, soft_thresh=False)

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_initFlow(self)
Should be called after buffer is full to compute the optical flow information on the buffered frames.

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getOpticalFlow(self)
Returns: A handle to the pv.OpticalFlow object being used by this object.

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setOpticalFlow(self, OF_Object)
This is an optional method that allows the user to provide an optical flow object (pv.OpticalFlow) with non-default settings.

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_computeBGDiff(self)
This private method should be overridden by a concrete background subtraction class to yield a difference image from the background model.

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Inherited from AbstractBGModel: getForegroundMask

Method Details

[hide private]

init(self, imageBuffer, thresh=20, soft_thresh=False)
(Constructor)

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Parameters:

imageBuffer - An ImageBuffer object that has already been filled with the appropriate number of images. (Provide a full buffer...so a few frames of initialization will be required in most cases to fill up a newly created buffer.)
thresh - A noise threshold to remove very small differences.

Overrides: AbstractBGModel.__init__

(inherited documentation)

_initFlow(self)

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Should be called after buffer is full to compute the optical flow information on the buffered frames. Only needs to be called once, prior to first call of _computeBGDiff(), because from then on, the flow will be updated as new frames are added to the buffer.