High Resolution Thermal Infrared Research Articles

Minimum configuration of thermal infrared bands for land surface temperature and emissivity estimation in the context of potential future missions

A number of applications rely on the availability of high resolution TIR data, both in terms of spatial and temporal resolution, as well as in terms of spectral configuration. A consensus exists among the thermal community regarding the lack of such a kind of data, since only one operational sensor is currently providing multispectral TIR data at high spatial resolution (the case of ASTER, at 90m spatial resolution and a 16-day revisit time). In this paper we propose a minimum multispectral configuration to allow the retrieval of both land surface temperature (LST) and emissivity (ε) from thermal infra-red (TIR) data. For this purpose, we propose a minimum configuration based on three TIR bands at around 8.9, 10.6 and 12.0μm, which allows the application of two-channel (or split-window) algorithms as well as the application of a temperature and emissivity separation (TES) method (or a combination of both) for LST retrieval. Results presented in this paper are based on studies performed for different candidate missions, but most of the presented results can be also valid in other contexts.

Thermal signature of fear conditioning in mild post traumatic stress disorder

Fear conditioning has been proposed as an important factor involved in the etiology of posttraumatic stress disorder (PTSD). We examined fear processing in PTSD patients with mild symptoms and in individuals who did not develop symptoms (both groups consisting of victims of a bank robbery), through the study of fear-conditioned response. Conditioned responses were quantified by the skin conductance response (SCR) and the facial thermal response, the latter being measured by high-resolution functional thermal infrared (fIR) imaging.We found: (a) a change of the physiological parameters with respect to the baseline condition in both control subjects and PTSD patients during the conditioning phase; (b) the permanence of the conditioning effect in the maintenance phase in both control and PTSD patients; (c) patients and controls did differ for the variation across the phases of the physiological parameters rather than for their absolute values, showing that PTSD patients had a prolonged excitation and higher tonic component of autonomic activity. These results, although preliminary, indicate that the analysis of SCR and facial thermal response during the conditioning paradigm is a promising psychometric method of investigation, even in the case of low level of PTSD symptom severity. To the best of our knowledge, this study is the first attempt to discriminate between control subjects and PTSD patients with mild symptoms through infrared thermal imaging. It may suggest feasible approaches for diagnostic screening in the early phases of the disorder and in the assessment of preventive measures and therapies.

Prediction of water temperature heterogeneity of braided rivers using very high resolution thermal infrared (TIR) images

Braided rivers exhibit high spatial thermal heterogeneity that is difficult to understand using only in situ measurements. In this summer study, we used a drone and a powered paraglider to acquire very high spatial resolution (14–27 cm) thermal infrared (TIR) images of nine braided reaches located in the French Alps. We applied atmospheric corrections to TIR images and calibrated them based on in situ data. To characterize spatial and temporal thermal patterns, three temporal approaches were applied. A single survey of each site was performed to comparatively explore the nine braided reaches. Three reaches were imaged twice, in 2010 and 2011, to explore inter-annual variability. Finally, two reaches were selected for an intra-day survey for which four and three flights, respectively, were realized within one day. We reported two types of thermal patterns in braided reaches, the first showing very low thermal variability throughout the day. This low variability was linked to the low diversity found in the aquatic habitat, notably due to proglacial regimes with high summer flows which homogenize water temperatures. The second type exhibited a higher thermal variability with changes during the day. The temperature of flowing channels changed during the daytime according to air temperature. In contrast, the temperature of channels downstream connected to the main network exhibited smaller changes, which created thermal variability over space and time associated with hyporheic or phreatic flows. Non-proglacial and proglacial reaches behaved differently according to air temperature. Proglacial reaches were colder and less sensitive to air temperature in comparison with non-proglacial reaches. These findings allow for a prediction of habitat diversity from temperature heterogeneity based on time and the proportion of ponds, alluvial, and groundwater channels.

High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at Redoubt Volcano, Alaska

A combination of satellite and airborne high-resolution visible and thermal infrared (TIR) image data detected and measured changes at Redoubt Volcano during the 2008–2009 unrest and eruption. The TIR sensors detected persistent elevated temperatures at summit ice-melt holes as seismicity and gas emissions increased in late 2008 to March 2009. A phreatic explosion on 15 March was followed by more than 19 magmatic explosive events from 23 March to 4 April that produced high-altitude ash clouds and large lahars. Two (or three) lava domes extruded and were destroyed between 23 March and 4 April. After 4 April, the eruption extruded a large lava dome that continued to grow until at least early July 2009.

Increasing the spatial resolution of thermal infrared images using cokriging

Thermal infrared (TIR) satellite images are of great interest in many remote sensing applications. However, owing to well-known physical reasons and technical limitations, the TIR band has a spatial resolution that is coarser than the other multispectral bands for a given satellite sensor, i.e. visible and shortwave IR. Although the correlation coefficient between the TIR band and the other spectral bands is relatively small, the spatial cross-correlation shows a pattern of joint variability. In this fact, and in the spatial correlation of each spectral band, reside the fundamentals of image fusion by cokriging. A method is showed here for obtaining TIR images with enhanced spatial resolution using the TIR band and one or more spectral bands of the same scene and better spatial resolution. The technique is illustrated with a Landsat 7 ETM+ image. The high resolution TIR image has perfect coherence, if the cokriged image is degraded to its original resolution the degraded image is identical to the original and values of ERGAS (Erreur Relative Globale Adimensionnelle de Synthèse) and average Q (Image Quality Index) equal to 0.220 and 0.986 respectively were obtained.

Postural adjustment in experimental leg length difference evaluated by means of thermal infrared imaging

Limb length discrepancy (LLD) is defined as a condition in which limbs are unequal. The asymmetric load of body segments secondary to LLD may cause a tonic contraction of back and lower limb muscles, thus resulting in subtle cutaneous temperature variations. The aim of this study was to test the capability of high-resolution thermal infrared (IR) imaging to measure the cutaneous temperature short-term adaptation, potentially associated with ‘forced’ LLD conditions. An experimental LLD, obtained by placing a 20 mm foot support under the dominant foot, was used. IR imaging on 18 male healthy volunteers was performed in three experimental conditions of standing position: (T0) neutral posture; (T1) experimental LLD; (T2) neutral posture as in T0. Temperature variations were evaluated on the cutaneous projection of postural muscles bellies. Significant and specific temperature variations among conditions were ipsilaterally observed on the tibialis anterior, gastrocnemius, quadriceps and latissimus dorsi muscles. Specific patterns characterized the cutaneous temperature as a consequence of the muscle activity associated with the posture variation. IR imaging was able to highlight specific functional activations. The method is non-invasive and it can be repeated without any discomfort for the physiopathological and clinical evaluation of LLD patients.

Determination of persistence effects in spatio-temporal patterns of upward long-wave radiation flux density from an urban courtyard by means of Time-Sequential Thermography

This research analyses upward long-wave radiation flux density from urban surfaces using a high-resolution thermal-infrared (TIR) camera and meteorological measurements in the city of Berlin, Germany. We report spatio-temporal patterns of the difference between upward long-wave radiation flux density from courtyard surfaces and the roof. For temporal analysis, the TIR camera recorded one TIR image per minute over a period of two days from 3rd to 5th May 2007. Three-hourly averaged thermal patterns show persistence effects due to shadow, sky-view factor (SVF) distribution in the courtyard, thermal properties of the surface materials, human activities and turbulence characteristics of the surface–atmosphere interface. The history of shadow influences the 24-hourly mean pattern. Shadow caused by temporarily parked cars results in a lower upward long-wave radiation flux density compared to the non-shadowed surface close to it. Immediately after car departure, this difference decreases. We propose a method to derive the thermal admittance of a concrete surface based on TIR data from this attenuation process. This study shows that ground-based high-resolution TIR imagery is highly suitable to investigate surface thermal properties and dynamic processes controlling thermal patterns within a complex three-dimensional (3D) urban structure.

Surface Temperature Mapping of the University of Northern Iowa Campus Using High Resolution Thermal Infrared Aerial Imageries.

The goal of this project was to map the surface temperature of the University of Northern Iowa campus using high-resolution thermal infrared aerial imageries. A thermal camera with a spectral bandwidth of 3.0-5.0 μm was flown at the average altitude of 600 m, achieving ground resolution of 29 cm. Ground control data was used to construct the pixel- to-temperature conversion model, which was later used to produce temperature maps of the entire campus and also for validation of the model. The temperature map then was used to assess the building rooftop conditions and steam line faults in the study area. Assessment of the temperature map revealed a number of building structures that may be subject to insulation improvement due to their high surface temperatures leaks. Several hot spots were also identified on the campus for steam pipelines faults. High-resolution thermal infrared imagery proved highly effective tool for precise heat anomaly detection on the campus, and it can be used by university facility services for effective future maintenance of buildings and grounds.

Evaluation of Airborne Thermal Infrared Imagery for Locating Mine Drainage Sites in the Lower Kettle Creek and Cooks Run Basins, Pennsylvania, USA

High-resolution airborne thermal infrared (TIR) imagery data were collected over 90.6 km2 (35 mi2) of remote and rugged terrain in the Kettle Creek and Cooks Run Basins, tributaries of the West Branch of the Susquehanna River in north-central Pennsylvania. The purpose of this investigation was to evaluate the effectiveness of TIR for identifying sources of acid mine drainage (AMD) associated with abandoned coal mines. Coal mining from the late 1800s resulted in many AMD sources from abandoned mines in the area. However, very little detailed mine information was available, particularly on the source locations of AMD sites. Potential AMD sources were extracted from airborne TIR data employing custom image processing algorithms and GIS data analysis. Based on field reconnaissance of 103 TIR anomalies, 53 sites (51%) were classified as AMD. The AMD sources had low pH (<4) and elevated concentrations of iron and aluminum. Of the 53 sites, approximately 26 sites could be correlated with sites previously documented as AMD. The other 27 mine discharges identified in the TIR data were previously undocumented. This paper presents a summary of the procedures used to process the TIR data and extract potential mine drainage sites, methods used for field reconnaissance and verification of TIR data, and a brief summary of water-quality data.