High-Resolution Urban Greenery Mapping for Micro-Climate Modelling Based on 3d City Models

Abstract

Commission VI, WG VI/4 KEY WORDS: urban greenery, 3D city model, LiDAR, urban microclimate ABSTRACT:Urban greenery has various positive micro-climate effects including mitigation of heat islands. The primary root of heat islands in cities is in absorption of solar radiation by the mass of building structures, roads and other solid materials. The absorbed heat is subsequently re-radiated into the surroundings and increases ambient temperatures. The vegetation can stop and absorb most of incoming solar radiation mostly via the photosynthesis and evapotranspiration process. However, vegetation in mild climate of Europe manifests considerable annual seasonality which can also contribute to the seasonal change in the cooling effect of the vegetation on the urban climate. Modern methods of high-resolution mapping and new generations of sensors have brought opportunity to record the dynamics of urban greenery in a high resolution in spatial, spectral, and temporal domains. In this paper, we use the case study of the city of Košice in Eastern Slovakia to demonstrate the methodology of 3D mapping and modelling the urban greenery during one vegetation season in 2016. The purpose of this monitoring is to capture 3D effects of urban greenery on spatial distribution of solar radiation in urban environment. Terrestrial laser scanning was conducted on four selected sites within Košice in ultra-high spatial resolution. The entire study area, which included these four smaller sites, comprised 4 km 2 of the central part of the city was flown within a single airborne lidar and photogrammetric mission to capture the upper parts of buildings and vegetation. The acquired airborne data were used to generate a 3D city model and the time series of terrestrial lidar data were integrated with the 3D city model. The results show that the terrestrial and airborne laser scanning techniques can be effectively used to monitor seasonal changes in foliage of trees in order to assess the transmissivity of the canopy for microclimate modelling.

Estimating Visible Band Albedo from Aerial Orthophotographs in Urban Areas

“…The methodology described above was applied to the data representing the inner city of Košice. The DSM and orthophotographs were prepared during our previous studies [14][15][16]. All calculation steps were completed in GRASS GIS.…”

“…The study area also contains residential zones with single family detached houses, blocks of flats (5-12 floors) and commercial buildings. The typical width of streets (urban canyons) is in the range of 10-20 m. The area was mapped during several surveying campaigns in 2016 and 2017 including photogrammetric, airborne and terrestrial laser scanning data [16]. In this study, we used RGB orthophotographs and a raster-based DSM representing terrain, buildings and urban greenery derived from airborne laser scanning and photogrammetry, both at 0.5-m spatial resolution.…”

Impact of 2050 tree shading strategies on building cooling demands

“…Advances in modeling three dimensional (3D) trees has also been conducted using light detection and ranging technology (i.e. lidar or aerial laser scanning-ALS) (Hofierka et al 2017;Zhang et al 2015). For example, Lu et al (2022) used ALS-based tree and building models to assess the tree canopy shading effect on roofs and exterior walls for Vancouver.…”

Modeling Diurnal Changes in Land Surface Temperature in Urban Areas under Cloudy Conditions

“…This study focuses on the central part of the Košice City in Eastern Slovakia (Figure 1) as an example of urban area typical for moderate climate of Central Europe that experiences hot summer days and associated UHI phenomenon [29]. The study area (4 km 2 ) was mapped in 2016 and 2017 during several surveying campaigns [30]. The collected data include photogrammetric, satellite, airborne and terrestrial laser scanning data.…”

“…In this study, we used a DSM with 0.5 m cell size derived from a 3D city model with a level of detail (LoD) 2 consisting of buildings, urban greenery and terrain (Figure 2) as well as spaceborne multispectral imagery of the Sentinel 2A satellite to derive albedo values for the LST model [21]. The study area (4 km 2 ) was mapped in 2016 and 2017 during several surveying campaigns [30]. The collected data include photogrammetric, satellite, airborne and terrestrial laser scanning data.…”