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Autor principal: Zawalski, Bartłomiej
Formato: Preprint
Publicado: 2026
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Acceso en línea:https://arxiv.org/abs/2603.29130
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author Zawalski, Bartłomiej
author_facet Zawalski, Bartłomiej
contents In his classical work, W. Blaschke proved that a convex body whose shadow boundaries are flat for every direction of parallel illumination must be an ellipsoid. An extension recently proposed by I. Gonzalez-García, J. Jerónimo-Castro, E. Morales-Amaya, and D.J. Verdusco-Hernández predicts that the same conclusion holds for illumination by point light sources located on a hypersurface enclosing the body. We confirm this conjecture for convex bodies with sufficiently smooth boundaries. We further develop a duality framework relating illumination by point light sources to classical symmetry properties of hyperplane sections, linking several known and conjectured characterizations of quadrics from these complementary viewpoints.
format Preprint
id arxiv_https___arxiv_org_abs_2603_29130
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On flat shadow boundaries from point light sources and the characterization of ellipsoids
Zawalski, Bartłomiej
Metric Geometry
Primary 53A07, Secondary 05D10, 15A69, 52A20, 53A15
In his classical work, W. Blaschke proved that a convex body whose shadow boundaries are flat for every direction of parallel illumination must be an ellipsoid. An extension recently proposed by I. Gonzalez-García, J. Jerónimo-Castro, E. Morales-Amaya, and D.J. Verdusco-Hernández predicts that the same conclusion holds for illumination by point light sources located on a hypersurface enclosing the body. We confirm this conjecture for convex bodies with sufficiently smooth boundaries. We further develop a duality framework relating illumination by point light sources to classical symmetry properties of hyperplane sections, linking several known and conjectured characterizations of quadrics from these complementary viewpoints.
title On flat shadow boundaries from point light sources and the characterization of ellipsoids
topic Metric Geometry
Primary 53A07, Secondary 05D10, 15A69, 52A20, 53A15
url https://arxiv.org/abs/2603.29130