Dual Band Thermal Videography: Separating Time-Varying Reflection and Emission Near Ambient Conditions

Fuente: arXiv
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Autores principales: Narayanan, Sriram, Ramanagopal, Mani, Narasimhan, Srinivasa G.
Formato: Preprint
Publicado: 2025
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author Narayanan, Sriram
Ramanagopal, Mani
Narasimhan, Srinivasa G.
author_facet Narayanan, Sriram
Ramanagopal, Mani
Narasimhan, Srinivasa G.
contents Long-wave infrared radiation captured by a thermal camera includes (a) emission from an object governed by its temperature and emissivity, and (b) reflected radiation from the surrounding environment. Separating these components is a long-standing challenge in thermography. Even when using multiple bands, the problem is under-determined without priors on emissivity. This difficulty is amplified in near ambient conditions, where emitted and reflected signals are of comparable magnitude. We present a dual-band thermal videography framework that reduces this ambiguity by combining two complementary ideas at a per-pixel level: (i) spectral cues (ratio of emissivity between bands is unknown but fixed), and (ii) temporal cues (object radiation changes smoothly while background radiation changes rapidly). We derive an image formation model and an algorithm to jointly estimate the object's emissivity at each band, and the time-varying object and background temperatures. Experiments with calibrated and uncalibrated emissivities in everyday scenes (e.g., coffee pot heating up, palm print on mirrors, reflections of moving people), demonstrate robust separation and recovery of temperature fields.
format Preprint
id arxiv_https___arxiv_org_abs_2509_11334
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dual Band Thermal Videography: Separating Time-Varying Reflection and Emission Near Ambient Conditions
Narayanan, Sriram
Ramanagopal, Mani
Narasimhan, Srinivasa G.
Computer Vision and Pattern Recognition
Long-wave infrared radiation captured by a thermal camera includes (a) emission from an object governed by its temperature and emissivity, and (b) reflected radiation from the surrounding environment. Separating these components is a long-standing challenge in thermography. Even when using multiple bands, the problem is under-determined without priors on emissivity. This difficulty is amplified in near ambient conditions, where emitted and reflected signals are of comparable magnitude. We present a dual-band thermal videography framework that reduces this ambiguity by combining two complementary ideas at a per-pixel level: (i) spectral cues (ratio of emissivity between bands is unknown but fixed), and (ii) temporal cues (object radiation changes smoothly while background radiation changes rapidly). We derive an image formation model and an algorithm to jointly estimate the object's emissivity at each band, and the time-varying object and background temperatures. Experiments with calibrated and uncalibrated emissivities in everyday scenes (e.g., coffee pot heating up, palm print on mirrors, reflections of moving people), demonstrate robust separation and recovery of temperature fields.
title Dual Band Thermal Videography: Separating Time-Varying Reflection and Emission Near Ambient Conditions
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2509.11334