Cast and Attached Shadow Detection via Iterative Light and Geometry Reasoning

Fuente: arXiv
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Hauptverfasser: Hu, Shilin, Xu, Jingyi, Das, Sagnik, Samaras, Dimitris, Le, Hieu
Format: Preprint
Veröffentlicht: 2025
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author Hu, Shilin
Xu, Jingyi
Das, Sagnik
Samaras, Dimitris
Le, Hieu
author_facet Hu, Shilin
Xu, Jingyi
Das, Sagnik
Samaras, Dimitris
Le, Hieu
contents Shadows encode rich information about scene geometry and illumination, yet existing methods either predict a unified shadow mask or overlook attached shadows entirely. We address this gap by proposing a framework for jointly detecting cast and attached shadows through explicit physical modeling of light direction and surface geometry. Our approach is grounded in a simple observation: surfaces facing away from the light source tend to fall into shadow. We exploit the reciprocal relationship between shadow formation and light estimation to construct a closed feedback loop, a dual-module architecture in which a shadow detection module and a light estimation module iteratively refine each other. At each pass, updated light estimates with surface normals produce partial attached shadow maps that guide detection, while improved shadow predictions sharpen light estimation. To support training and evaluation, we introduce a dataset of 1,458 images with manually annotated cast and attached shadow masks sourced from three existing benchmarks. Experiments demonstrate that our physically grounded, iterative formulation outperforms prior methods, with at least a 33% reduction in attached BER, while maintaining strong full and cast performance.
format Preprint
id arxiv_https___arxiv_org_abs_2512_06179
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Cast and Attached Shadow Detection via Iterative Light and Geometry Reasoning
Hu, Shilin
Xu, Jingyi
Das, Sagnik
Samaras, Dimitris
Le, Hieu
Computer Vision and Pattern Recognition
Shadows encode rich information about scene geometry and illumination, yet existing methods either predict a unified shadow mask or overlook attached shadows entirely. We address this gap by proposing a framework for jointly detecting cast and attached shadows through explicit physical modeling of light direction and surface geometry. Our approach is grounded in a simple observation: surfaces facing away from the light source tend to fall into shadow. We exploit the reciprocal relationship between shadow formation and light estimation to construct a closed feedback loop, a dual-module architecture in which a shadow detection module and a light estimation module iteratively refine each other. At each pass, updated light estimates with surface normals produce partial attached shadow maps that guide detection, while improved shadow predictions sharpen light estimation. To support training and evaluation, we introduce a dataset of 1,458 images with manually annotated cast and attached shadow masks sourced from three existing benchmarks. Experiments demonstrate that our physically grounded, iterative formulation outperforms prior methods, with at least a 33% reduction in attached BER, while maintaining strong full and cast performance.
title Cast and Attached Shadow Detection via Iterative Light and Geometry Reasoning
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2512.06179