Christian S. Pilz

This work addresses the problem of estimating heart rate from face videos under real conditions using a model based on the recursive inference problem that leverages the local invariance of the heart rate. The proposed solution is based on the canonical state space representation of an Itō process and a Wiener velocity model. Empirical results yiel...

We study the impact of prior knowledge about invariance for the task of heart rate estimation from face videos in the wild (e.g. in presence of disturbing factors like rigid head motion, talking, facial expressions and natural illumination conditions under different scenarios). We introduce features invariant with respect to the action of a differe...

We study the vector space of visible wavelength intensities from face videos widely used as input features in Pho-toplethysmography Imaging (PPGI). Based upon theoretical principles of group invariance in the Euclidean space, we derive a change of the topology where the corresponding distance between successive measurements is defined as geodesic o...

We investigate the regulation of human brain arousal in the central nervous system and its synchronization with the autonomic nervous system affecting the facial dynamics and its behavioral gestalt. A major focus is made on the sensing observable during natural human eye to eye communication. Although the inner state of the autopoietic system is de...

We study the statistical properties of facial behaviour altered by the regulation of brain arousal in the clinical domain of psychiatry. The underlying mechanism is linked to the empirical interpretation of the vigilance continuum as behavioral surrogate measurement for certain states of mind. Referring to the classical scalp-based obtrusive measur...

We study the vector space of visible wavelength intensities from face videos widely used as input features in Photoplethysmography Imaging (PPGI). Based upon theoretical principles of Group invariance in the Euclidean space we derive a change of the topology where the corresponding distance between successive measurements is defined as geodesic on...

The role of physiological signals has a large impact on driver monitoring systems, since it tells something about the human state. This work addresses the recursive probabilistic inference problem in time-varying linear dynamic systems to incorporate invariance into the task of heart rate estimation from face videos under realistic conditions. The...

Method for controlling user access to a service available in a data network and/or to information stored in a user database, in order to protect stored user data from unauthorized access, such that the method comprises the following: input of a user's speech sample to a user data terminal, processing of the user's speech sample in order to obtain a...

Digital method for authentication of a person by comparing a current voice profile with a previously stored initial voice profile, wherein to determine the relevant voice profile the person speaks at least one speech sample into the system, this speech sample is conveyed to a voice-profile calculation unit and thereby, on the basis of a prespecifie...