## 1 Introduction
### Modelling Direct/Diffuse Solar Radiation  
In an environment with tall vegetation, the influence of the spatial distribution of canopies plays a key role in calculating comfort indices at a specific position in space. A location will receive a certain fraction of direct vs. diffuse radiation from sunlight depending on the time of day, day of the year, and nearby objects. The quantification of the effect of canopy obstruction/gaps with respect to solar illumination is an important parameter that affects comfort indices as well as ecological diversity, as direct sunlight can affect the microclimate with impacts on the habitat distribution of plants and animals [11]. The estimation of the canopy cover and the amount of the leaf area is a critical process performed by terrestrial surveys, measuring the width and length of the gaps using hemispherical images or by applying remote sensing analysis [12]. None of the methods can be considered better than any others, since they are affected by bias and estimation errors [13; 14], but the hemispherical photo method is the most widely used technique. For extensive areas, remote sensing analysis is preferred in contrast to a terrestrial investigation, which is time-consuming and expensive [15].  
As mentioned above, indicators of people's physiological comfort, but also psychological well-being, are calculated using the environmental variables. Those indices can give guidance for urban planning at different scales for studying the interaction of the micro-climate in urban gardens and parks. Physiological comfort and psychological well-being, resulting from exposure to vegetation, are related to the canopy distribution, presence of buildings and water bodies, and variates seasonally [16]. In addition, these areas are aggregation spots that attract different types of users, from the young to the elderly, and each of these groups has different requirements regarding well-being. Data collected with sensors placed at 1.5 m above the ground between 7:00 AM and 5:00 PM have shown a high correlation between PET and solar radiation, where the feeling of comfort increases in naturally and artificially shaded areas and near water [17]. A study conducted on eight gardens in Chengdu City showed the optimal ratio between evergreen and deciduous plants to be 1:3, where the elderly need a more warm, humid, and sunlight-exposed microclimate to improve their degree of comfort [18].  
In this study, we calculate and map comfort indices of the garden of Villa Revedin-Bolasco using a real-time data flow of environmental variables. We map the spatial distribution of direct solar radiation values using a 3D model from an airborne LiDAR acquisition of the entire garden. We describe the implementation of a LoRa IoT network in the garden of Villa Revedin Bolasco for collecting data from several environmental sensors. The LoRa antennas collect, in real-time, the data streams of several environmental sensors installed in the garden in a fixed position that can also be deployed on a mobile rover. The environmental variables, namely the air temperature, relative humidity, solar radiation, wind speed, wind direction, and air quality, are stored in a database management system (DBMS). The advantage of this method is the creation of an accessible, spatially distributed, temporally dense data repository of several environmental variables. Moreover, data visualization and analysis are implemented on a web application, so that comfort maps can be calculated in real-time and integrated into a geographic information stem (GIS), and/or simulations of comfort can be carried out at the scale of the urban garden.