Goto

Collaborating Authors

 observer



How to Film ICE

WIRED

Filming federal agents in public is legal, but avoiding a dangerous--even deadly--confrontation isn't guaranteed. Here's how to record ICE and CBP agents as safely as possible and have an impact. In January 2026, two Americans were killed in the act of watching Immigration and Customs Enforcement operations in Minneapolis. Renee Nicole Good was acting as a legal observer while her wife recorded the federal immigration agents they encountered. Alex Pretti was holding a phone in his hand, filming the agents who would soon take his life.


From Entropy to Epiplexity: Rethinking Information for Computationally Bounded Intelligence

Finzi, Marc, Qiu, Shikai, Jiang, Yiding, Izmailov, Pavel, Kolter, J. Zico, Wilson, Andrew Gordon

arXiv.org Machine Learning

Can we learn more from data than existed in the generating process itself? Can new and useful information be constructed from merely applying deterministic transformations to existing data? Can the learnable content in data be evaluated without considering a downstream task? On these questions, Shannon information and Kolmogorov complexity come up nearly empty-handed, in part because they assume observers with unlimited computational capacity and fail to target the useful information content. In this work, we identify and exemplify three seeming paradoxes in information theory: (1) information cannot be increased by deterministic transformations; (2) information is independent of the order of data; (3) likelihood modeling is merely distribution matching. To shed light on the tension between these results and modern practice, and to quantify the value of data, we introduce epiplexity, a formalization of information capturing what computationally bounded observers can learn from data. Epiplexity captures the structural content in data while excluding time-bounded entropy, the random unpredictable content exemplified by pseudorandom number generators and chaotic dynamical systems. With these concepts, we demonstrate how information can be created with computation, how it depends on the ordering of the data, and how likelihood modeling can produce more complex programs than present in the data generating process itself. We also present practical procedures to estimate epiplexity which we show capture differences across data sources, track with downstream performance, and highlight dataset interventions that improve out-of-distribution generalization. In contrast to principles of model selection, epiplexity provides a theoretical foundation for data selection, guiding how to select, generate, or transform data for learning systems.


Optimal visual search based on a model of target detectability in natural images

Neural Information Processing Systems

To analyse visual systems, the concept of an ideal observer promises an optimal response for a given task. Bayesian ideal observers can provide optimal responses under uncertainty, if they are given the true distributions as input. In visual search tasks, prior studies have used signal to noise ratio (SNR) or psychophysics experiments to set the distributional parameters for simple targets on backgrounds with known patterns, however these methods do not easily translate to complex targets on natural scenes. Here, we develop a model of target detectability in natural images to estimate the parameters of target-present and target-absent distributions for a visual search task. We present a novel approach for approximating the foveated detectability of a known target in natural backgrounds based on biological aspects of human visual system. Our model considers both the uncertainty about target position and the visual system's variability due to its reduced performance in the periphery compared to the fovea. Our automated prediction algorithm uses trained logistic regression as a post processing phase of a pre-trained deep neural network. Eye tracking data from 12 observers detecting targets on natural image backgrounds are used as ground truth to tune foveation parameters and evaluate the model, using cross-validation. Finally, the model of target detectability is used in a Bayesian ideal observer model of visual search, and compared to human search performance.


Cascaded Tightly-Coupled Observer Design for Single-Range-Aided Inertial Navigation

Sifour, Oussama, Berkane, Soulaimane, Tayebi, Abdelhamid

arXiv.org Artificial Intelligence

This work introduces a single-range-aided navigation observer that reconstructs the full state of a rigid body using only an Inertial Measurement Unit (IMU), a body-frame vector measurement (e.g., magnetometer), and a distance measurement from a fixed anchor point. The design first formulates an extended linear time-varying (LTV) system to estimate body-frame position, body-frame velocity, and the gravity direction. The recovered gravity direction, combined with the body-frame vector measurement, is then used to reconstruct the full orientation on $\mathrm{SO}(3)$, resulting in a cascaded observer architecture. Almost Global Asymptotic Stability (AGAS) of the cascaded design is established under a uniform observability condition, ensuring robustness to sensor noise and trajectory variations. Simulation studies on three-dimensional trajectories demonstrate accurate estimation of position, velocity, and orientation, highlighting single-range aiding as a lightweight and effective modality for autonomous navigation.




Learning-Enhanced Observer for Linear Time-Invariant Systems with Parametric Uncertainty

Shu, Hao

arXiv.org Artificial Intelligence

This work introduces a learning-enhanced observer (LEO) for linear time-invariant systems with uncertain dynamics. Rather than relying solely on nominal models, the proposed framework treats the system matrices as optimizable variables and refines them through gradient-based minimization of a steady-state output discrepancy loss. The resulting data-informed surrogate model enables the construction of an improved observer that effectively compensates for moderate parameter uncertainty while preserving the structure of classical designs. Extensive Monte Carlo studies across diverse system dimensions show systematic and statistically significant reductions, typically exceeding 15\%, in normalized estimation error for both open-loop and Luenberger observers. These results demonstrate that modern learning mechanisms can serve as a powerful complement to traditional observer design, yielding more accurate and robust state estimation in uncertain systems. Codes are available at https://github.com/Hao-B-Shu/LTI_LEO.



Supplementary Material

Neural Information Processing Systems

The supplementary material is structured as follows. We start with terminology in Section S.1, afterwards we In addition to method details, we provide extended experimental results in Figure SF.3 (error consistency of all Furthermore, Figure SF.4 visualises qualitative error differences by plotting which stimuli were particularly easy We would like to briefly clarify the name error consistency . Two decision makers necessarily show some degree of consistency due to chance agreement. How much observed consistency can we expect at most for a given expected consistency? We distinguish between two cases.