Achieving high-resolution thermal imagery in low-contrast lake surface waters by aerial remote sensing and image registration

REMOTE SENSING OF ENVIRONMENT

卷:221

Article

Rahaghi, Abolfazl Irani¹  Lemmin, Ulrich¹  Sage, Daniel²  Barry, David Andrew¹ 

[1] Ecole Polytech Fed Lausanne EPFL, Ecol Engn Lab ECOL, Environm Engn Inst IIE, Fac Architecture Civil & Environm Engn ENAC, CH-1015 Lausanne, Switzerland

[2] Ecole Polytech Fed Lausanne EPFL, Biomed Imaging Grp BIG, Sch Engn STI, CH-1015 Lausanne, Switzerland

关键词: Aerial remote sensing;    Thermal imagery;    Lake surface water temperature;    Image registration;    Uncooled infrared camera;    Lake Geneva;   

DOI  :  10.1016/j.rse.2018.12.018

来源: Elsevier

【 摘 要 】

A two-platform measurement system for realizing airborne thermography of the Lake Surface Water Temperature (LSWT) with similar to 0.8 m pixel resolution (sub-pixel satellite scale) is presented. It consists of a tethered Balloon Launched Imaging and Monitoring Platform (BLIMP) that records LSWT images and an autonomously operating catamaran (called ZiviCat) that measures in situ surface/near surface temperatures within the image area, thus permitting simultaneous ground-truthing of the BLIMP data. The BLIMP was equipped with an uncooled InfraRed (IR) camera. The ZiviCat was designed to measure along predefined trajectories on a lake. Since LSWT spatial variability in each image is expected to be low, a poor estimation of the common spatial and temporal noise of the IR camera (nonuniformity and shutter-based drift, respectively) leads to errors in the thermal maps obtained. Nonuniformity was corrected by applying a pixelwise two-point linear correction method based on laboratory experiments. A Probability Density Function (PDF) matching in regions of overlap between sequential images was used for the drift correction. A feature matching-based algorithm, combining blob and region detectors, was implemented to create composite thermal images, and a mean value of the overlapped images at each location was considered as a representative value of that pixel in the final map. The results indicate that a high overlapping field of view (similar to 95%) is essential for image fusion and noise reduction over such low-contrast scenes. The in situ temperatures measured by the ZiviCat were then used for the radiometric calibration. This resulted in the generation of ISWT maps at sub-pixel satellite scale resolution that revealed spatial LSWT variability, organized in narrow streaks hundreds of meters long and coherent patches of different size, with unprecedented detail.

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