Pattern identification and analysis for the traditional village using low altitude UAV-borne remote sensing: multifeatured geospatial data to support rural landscape investigation, documentation and management

Li, Chun; Cao, Yujie; Yang, Chen; Zhou, Yuan; Ai, Mengchi

doi:10.1016/j.culher.2019.12.013

Cited by 25 publications

(17 citation statements)

References 33 publications

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“…Owing to the advantages of low cost, high resolution and high efficiency, UAVs are widely used in the fields of industry, agriculture, forestry and construction [34][35][36][37]. In the field of urban planning and city management, this technology is often used to obtain 3D models for satisfying research demand from governments and designers [8].…”

Section: Methodsmentioning

confidence: 99%

Analysis of the Thermal Environment in Pedestrian Space Using 3D Thermal Imaging

Zhao

Luo²,

2020

Energies

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Pedestrian space is an important place for people’s outdoor activities. Its thermal environment affects pedestrian walking experience, route selection and physical health. This study presents a 3D thermography-based method to analyze and evaluate the spatial distribution of thermal comfort. The proposed 3D thermal image was generated using 3D city models captured by an unmanned aerial vehicle (UAV) and thermal images gathered by an infrared camera. It can visualize construction elements, but also simply output surface temperatures at selected points. This paper described the process of using 3D thermal images to analyze the built environment, and selected two pedestrian spaces as case study objects. Their thermal images and mean radiant temperatures (MRT) were obtained from field measurement data collected by a drone and infrared camera. The following findings were obtained: (a) the MRT difference in the pedestrian space between sunlit and shaded areas was more than 3 °C; (b) the MRT values at the measurement points near vegetation were lower; (c) when the ratio of street height to width (H/W) was larger, the MRT values at all measurement points varied slightly. These findings can be used for the designers to evaluate and improve the thermal environment in pedestrian space.

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Section: Methodsmentioning

confidence: 99%

Analysis of the Thermal Environment in Pedestrian Space Using 3D Thermal Imaging

Zhao

Luo²,

2020

Energies

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“…The use of drones equipped with an on-board multi-frequency multi-constellation GNSS receiver used in Real-Time Kinematic (RTK), Network RTK (NRTK), or Post-Processing Kinematic (PPK) modes makes the use of direct georeferencing techniques with a centimeter-level accuracy of camera locations possible [24,25]. The most common field of application is the mapping of a broad land extent [26,27], with the subsequent production of orthomosaics and digital elevation models without the need for surveying a high number of GCPs [28][29][30]. In any case, whichever it is the GNSS kinematic mode adopted, the vertical accuracy of the photogrammetric models that were obtained is strongly related to a consistent estimate of the focal length of the camera, in particular, for nadiral datasets [31].…”

Section: Introductionmentioning

confidence: 99%

Quality Assessment of Photogrammetric Models for Façade and Building Reconstruction Using DJI Phantom 4 RTK

et al. 2020

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Aerial photogrammetry by Unmanned Aerial Vehicles (UAVs) is a widespread method to perform mapping tasks with high-resolution to reconstruct three-dimensional (3D) building and façade models. However, the survey of Ground Control Points (GCPs) represents a time-consuming task, while the use of Real-Time Kinematic (RTK) drones allows for one to collect camera locations with an accuracy of a few centimeters. DJI Phantom 4 RTK (DJI-P4RTK) combines this with the possibility to acquire oblique images in stationary conditions and it currently represents a versatile drone widely used from professional users together with commercial Structure-from-Motion software, such as Agisoft Metashape. In this work, we analyze the architectural application of this drone to the photogrammetric modeling of a building with particular regard to metric survey specifications for cultural heritage for 1:20, 1:50, 1:100, and 1:200 scales. In particular, we designed an accuracy assessment test signalizing 109 points, surveying them with total station and adjusting the measurements through a network approach in order to achieve millimeter-level accuracy. Image datasets with a designed Ground Sample Distance (GSD) of 2 mm were acquired in Network RTK (NRTK) and RTK modes in manual piloting and processed both as single façades (S–F) and as an overall block (4–F). Subsequently, we compared the results of photogrammetric models generated in Agisoft Metashape to the Signalized Point (SP) coordinates. The results highlight the importance of processing an overall photogrammetric block, especially whenever part of camera locations exhibited a poorer accuracy due to multipath effects. No significant differences were found between the results of network real-time kinematic (NRTK) and real-time kinematic (RTK) datasets. Horizontal residuals were generally comparable to GNSS accuracy in NRTK/RTK mode, while vertical residuals were found to be affected by an offset of about 5 cm. We introduced an external GCP or used one SP per façade as GCP, assuming a poorer camera location accuracy at the same time, in order to fix this issue and comply with metric survey specifications for the widest architectural scale range. Finally, both S–F and 4–F projects satisfied the metric survey requirements of a scale of 1:50 in at least one of the approaches tested.

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“…This, coupled with other features such as low cost and high efficiency [69,70], makes UAS a great candidate for mapping buildings in remote settlements. Successful applications of such kind have been demonstrated in villages in China [71], Dominican Republic [72], and Rwanda [73]. In addition to the aforementioned advantages, another capacity of UAS-based VHR is the ability to generate the 3-d structure of the buildings.…”

Section: Technical Innovation and Future Directionsmentioning

confidence: 99%

Characterizing Small-Town Development Using Very High Resolution Imagery within Remote Rural Settings of Mozambique

et al. 2021

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While remotely sensed images of various resolutions have been widely used in identifying changes in urban and peri-urban environments, only very high resolution (VHR) imagery is capable of providing the information needed for understanding the changes taking place in remote rural environments, due to the small footprints and low density of man-made structures in these settings. However, limited by data availability, mapping man-made structures and conducting subsequent change detections in remote areas are typically challenging and thus require a certain level of flexibility in algorithm design that takes into account the specific environmental and image conditions. In this study, we mapped all buildings and corrals for two remote villages in Mozambique based on two single-date VHR images that were taken in 2004 and 2012, respectively. Our algorithm takes advantage of the presence of shadows and, through a fusion of both spectra- and object-based analysis techniques, is able to differentiate buildings with metal and thatch roofs with high accuracy (overall accuracy of 86% and 94% for 2004 and 2012, respectively). The comparison of the mapping results between 2004 and 2012 reveals multiple lines of evidence suggesting that both villages, while differing in many aspects, have experienced substantial increases in the economic status. As a case study, our project demonstrates the capability of a coupling of VHR imagery with locally adjusted classification algorithms to infer the economic development of small, remote rural settlements.

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Pattern identification and analysis for the traditional village using low altitude UAV-borne remote sensing: multifeatured geospatial data to support rural landscape investigation, documentation and management

Cited by 25 publications

References 33 publications

Analysis of the Thermal Environment in Pedestrian Space Using 3D Thermal Imaging

Analysis of the Thermal Environment in Pedestrian Space Using 3D Thermal Imaging

Quality Assessment of Photogrammetric Models for Façade and Building Reconstruction Using DJI Phantom 4 RTK

Characterizing Small-Town Development Using Very High Resolution Imagery within Remote Rural Settings of Mozambique

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