## 1 Introduction  
Various environmental problems caused by climate change are directly threatening the ecological stability of cities, and urban ecosystem services are becoming vulnerable due to population growth and reductions in green spaces. As a result, demand to improve the health of urban ecosystems is constantly growing. In major cities worldwide, efforts are being made to restore damaged urban ecosystems and secure additional urban ecological spaces. For example, healthy city development projects are being implemented in more than 3000 cities globally, led by the World Health Organization (WHO), to improve urban residents' health and environments. In particular, because green spaces in cities offer a various benefits that include providing habitats for organisms, controlling the urban microclimate, reducing air pollution, preventing floods, providing leisure and recreation opportunities, and saving energy [1; 2; 3], the expansion and utilization of parks and green areas are widely considered as a representative means to achieve this objective [4; 5; 6]. In a city where urbanization has already considerably progressed however, it is almost impossible to create new large green space due to high development demand and land prices. As a result, small green spaces such as green roofs and roadside trees are gaining attention as key features that can increase ecosystem services in cities. In urban areas, the area of individual buildings tends to be small, but the sum of all buildings' rooftops accounts for a large area. For example, in New York City, the sum of building rooftops is known to be 20 to 30 times the size of Central Park [7]. [PERSON], [PERSON], and [PERSON] [8] reported that 20-25% of the total area of major U.S. cities such as Salt Lake City, Sacramento, Houston, and Chicago is rooftop area. Notably, rooftops can be a good alternative for increasing green spaces in cities where additional space is difficult to secure owing to high land prices and various conflicts of interest [9; 10]. As a result, several studies [11; 12; 13; 14] were conducted to effectively create rooftop greening and roadside trees in cities. [PERSON] [11] proposed a conceptual description of the individual effects of trees and offers a guideline for tree planting to increase such effects. [PERSON] et al. [10] and [PERSON] and [PERSON] [11] presented a species of trees that can effectively adapt to climate change, and the authors provide their respective planting methods and management measures. [PERSON] and [PERSON] [14] established a geographic information system (GIS)-based location analysis algorithm in Hong Kong's Open Space Plan to calculate the amount of additional green spaces needed, plus potential locations and areas according to the population. [PERSON] et al. [15] assessed possible locations for greening and the possible total amount of greening in Los Angeles using GIS spatial analysis and considering the features of roadside trees. However, for rooftop greening, in most cases, the possible areas are indirectly estimated with a certain ratio of the total area of rooftops. In addition, even though relatively clear installation standards exist for planting soil, drinking water density (per square meter), and maintenance measures for rooftop greening, there is still insufficient research on the characteristics of buildings suitable for rooftop greening and the available rooftops [16; 17]. Although it is possible to analyze the possibility of greening with regard to the type, size, and delivery method of trees, roadside trees have been planted by mainly relying on the subjective judgment of planners in terms of landscape improvement. Unlike large-scale urban planning facilities, small-scale projects like rooftop greening and roadside tree planting require the acquisition of detailed and extensive spatial-attribute data and various spatial analysis functions including queries, overlapping, and buffers.