arXiv Computer Vision

Scale-Vector Alignment: A Scale-Aware Framework for Spatially Resolved Morphological Similarity in Astronomical Images

arXiv Computer Vision
Sep 4

Spectral Hierarchy of the Cosmic Web

The paper presents a spectral hierarchy for classifying the cosmic web by applying scale-weighting kernels to the density field before using eigenvalue-based methods. This framework unifies existing web definitions—potential/tidal, curvature-based, and higher-derivative levels—into a single, interpretable hierarchy that captures structure from large to small scales. The authors quantify the hierarchy’s information content by correlating a web contrast field with halo distributions, showing that it retains significant tracer-relevant information across scales, especially at nonlinear levels.

By Francisco-Shu Kitaura, Francesco Sinigaglia
arXiv Computer Vision
Oct 19

A Unified Theory of Image Scaling: Point Spread Functions, Discrete Kernels, and Scale-Spaces

The paper presents a closed‑form system of image‑scaling operators <K_s> that faithfully reproduce optical zoom by leveraging the camera’s point spread function (PSF). These operators compose multiplicatively, form a Moore‑Penrose pseudoinverse pair, and provide a generalized, bidirectional scale‑space that extends beyond conventional Gaussian kernels. The authors validate the model with real captures and simulations, showing improved stability for tasks such as super‑resolution and classification.

By Assaf Shocher
arXiv AI
Aug 26

A survey detection channel overrides the pixels in an astronomical foundation model, and biases tomographic mean redshifts

The study audits the AION-1 foundation model, a 39‑modality transformer trained on over 200 million astronomical objects, and finds that its reliance on a survey detection channel—specifically the segmentation map—introduces a severe systematic bias. By keeping image tokens unchanged and editing only the segmentation map, all model outputs (flux, size, ellipticity, redshift) shift by factors of 110–4400 compared to a placebo, revealing that the model’s predictions are driven more by detection gating than by the actual light distribution. This bias propagates into cosmological analyses, shifting tomographic mean redshifts by a median 0.71 × the LSST DESC requirement and exceeding it in multiple assignments, while removing the detection channel eliminates the effect without measurable cost. whyItMatters":"The bias in the detection channel directly inflates errors in key astronomical measurements, potentially compromising the precision of cosmological studies that rely on accurate redshift estimates."

By Ihor Kendiukhov