Urban surfaces studied by VIS/NIR imaging from UAV: possibilities and limitations

Burud, I.; Vukovic, Marija; Thiis, Thomas K.; Gaitani, Niki

doi:10.1117/12.2326057

Cited by 3 publications

(4 citation statements)

References 15 publications

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“…In recent years, there have been many examples of successful use of UAV-based thermal studies in different parts of the world. For instance, in several studies, Gaitani et al [72][73][74] presented the results of a thermal survey in a suburb of Athens, and Naughton & McDonald [75] used a UAV quadcopter drone and thermal camera at two university campuses in Milwaukee (Wisconsin) and El Paso (Texas). However, we are not aware of any UAV-based thermal studies of LCZs that have been performed so far throughout the whole city.…”

Section: Introductionmentioning

confidence: 99%

An Application of the LCZ Approach in Surface Urban Heat Island Mapping in Sofia, Bulgaria

2021

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This article presents the results of the thermal survey of the capital of Bulgaria (Sofia) carried out in August 2019, with the application of an unmanned aerial system (UAS). The study is based on the concept of local climate zones (LCZs), taking into account the influence of the features of land use/land cover and urban morphology on the urban climate. The basic spatial units used in the study are presented in the form of a regular grid consisting of 3299 cells with sides of 250 ´ 250 m. A total of 13 types of LCZs were identified, of which LCZs 6, 5, 8, 4, D, and A form the largest share. In the thermal imaging of the surface, a stratified sampling scheme was applied, which allowed us to select 74 cells, which are interpreted as representative of all cells belonging to the corresponding LCZ in the urban space. The performed statistical analysis of the thermal data allowed us to identify both the most thermally loaded zones (LCZs 9, 4, and 5) and the cells forming Urban Cool Islands (mainly in LCZs D and C). The average surface temperature in Sofia during the study period (in the time interval between 8:00 PM and 10:00 PM) was estimated at 20.9 °C, and between the different zones it varied in the range 17.2–25.1 °C. The highest maximum values of LST (27.9–30.6 °C) were registered in LCZ 4 and LCZ 5. The relation between the spatial structure of the urban thermal patterns and urban surface characteristics was also analyzed. Regression analysis confirmed the hypothesis that as the proportion of green areas increases, surface temperatures decrease, and, vice versa, as the proportion of built-up and impermeable areas increases, surface temperatures increase. A heat load map (via applying a z-transformation to standardize the temperature values), a map of the average surface temperature, and a map of the average intensity of the heat island on the surface were generated in the GIS environment. The results of the study adequately reflect the complex spatial model of the studied phenomenon, which gives grounds to conclude that the research approach used is applicable to similar studies in other cities.

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Section: Introductionmentioning

confidence: 99%

An Application of the LCZ Approach in Surface Urban Heat Island Mapping in Sofia, Bulgaria

2021

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“…Recent trends in both technological solutions and data analytics offer new pathways to overcome monitoring challenges. Smaller scale unmanned autonomous vehicles (UAVs) equipped with thermal and multi/hyperspectral camerascancollecturbanimageryatmoresuitabletimesoftheday (Gaitani et al 2017;Burud et al 2018). In addition, merging differentdataproductscangeneratesyntheticremotesensingequivalent imagery, based on complementary datasets including satellite imagery from multiple sensors with different spatial and temporal scales, and local vector-based geo-information such as built-up contours and land use-land cover classification (Zurita-Milla et al 2009;Weng et al 2014).…”

Section: Local Regional and Synoptic Scale Sensingmentioning

confidence: 99%

Technological opportunities for sensing of the health effects of weather and climate change: a state-of-the-art-review

et al. 2021

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Sensing and measuring meteorological and physiological parameters of humans, animals, and plants are necessary to understand the complex interactions that occur between atmospheric processes and the health of the living organisms. Advanced sensing technologies have provided both meteorological and biological data across increasingly vast spatial, spectral, temporal, and thematic scales. Information and communication technologies have reduced barriers to data dissemination, enabling the circulation of information across different jurisdictions and disciplines. Due to the advancement and rapid dissemination of these technologies, a review of the opportunities for sensing the health effects of weather and climate change is necessary. This paper provides such an overview by focusing on existing and emerging technologies and their opportunities and challenges for studying the health effects of weather and climate change on humans, animals, and plants.

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“…Techniques of 3-D modelling, like structure-from-motion (SfM) [17], were combined to process the acquired UAV photos and to construct the digital elevation model (DEM). The landscape of an urban area can be investigated in detail with the acquisition of multi-band UAV imagery [18], which can yield more valuable information than satellite imagery.…”

Section: Introductionmentioning

confidence: 99%

“…The separated flight enables a closer watch on the objects, increases photo overlaps, decreases the pixel size and improves image resolution. In addition, auxiliary data such as camera global positioning system (GPS) data and ground control points (GCPs) are usually more indispensable during thermal mosaicking than RGB mosaicking [18,39,40]. However, planning a separated flight mission and setting GCP boards on the ground [31,38] beforehand are both labor intensive, not to mention that the thermal band will have a smaller sampled area compared to the RGB band.…”

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confidence: 99%

Four-band Thermal Mosaicking: A New Method to Process Infrared Thermal Imagery of Urban Landscapes from UAV Flights

Yang

Lee

2019

Remote Sensing

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Unmanned aerial vehicles (UAVs) support a large array of technological applications and scientific studies due to their ability to collect high-resolution image data. The processing of UAV data requires the use of mosaicking technology, such as structure-from-motion, which combines multiple photos to form a single image mosaic and to construct a 3-D digital model of the measurement target. However, the mosaicking of thermal images is challenging due to low lens resolution and weak contrast in the single thermal band. In this study, a novel method, referred to as four-band thermal mosaicking (FTM), was developed in order to process thermal images. The method stacks the thermal band obtained by a thermal camera onto the RGB bands acquired on the same flight by an RGB camera and mosaics the four bands simultaneously. An object-based calibration method is then used to eliminate inter-band positional errors. A UAV flight over a natural park was carried out in order to test the method. The results demonstrated that with the assistance of the high-resolution RGB bands, the method enabled successful and efficient thermal mosaicking. Transect analysis revealed an inter-band accuracy of 0.39 m or 0.68 times the ground pixel size of the thermal camera. A cluster analysis validated that the thermal mosaic captured the expected contrast of thermal properties between different surfaces within the scene.3 of 17 register, with sufficient positional accuracy, the thermal mosaic to the RGB imagery of the same target for proper interpretation of the former [29].Motivated by these challenges and the importance of thermal mosaicking, this work aims to design a novel method, referred to as the four-band thermal mosaicking (FTM), in order to process thermal images acquired by a UAV, with three goals in mind:

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Urban surfaces studied by VIS/NIR imaging from UAV: possibilities and limitations

Cited by 3 publications

References 15 publications

An Application of the LCZ Approach in Surface Urban Heat Island Mapping in Sofia, Bulgaria

An Application of the LCZ Approach in Surface Urban Heat Island Mapping in Sofia, Bulgaria

Technological opportunities for sensing of the health effects of weather and climate change: a state-of-the-art-review

Four-band Thermal Mosaicking: A New Method to Process Infrared Thermal Imagery of Urban Landscapes from UAV Flights

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