research
2020.06.25 Thursday

The HIKAGE FINDER

Summer in Tokyo is incredibly hot!

The temperature can reach around 40℃ with high humidity. The hot summer environment significantly decreases people’s motivation to walk outdoors, resulting in reduced quality of life – they can’t fully enjoy what the city has to offer them. To address this problem, we created an app that looks for shaded paths in Tokyo’s Shibuya district. HIKAGE FINDER helps you explore the city in comfort by identifying the coolest paths, rather than the shortest ones. It avoids areas of direct sunlight, meaning you can walk more comfortably on those hot summer days. This is how HIKAGE FINDER can enhance your enjoyment of life in the city.

TECHNICAL DESCRIPTION

1.Google Street Views along with the street network

hikage_finder

We collected Google Street View images and obtained a street network from Open Street Map. We set a collecting point every 10 meters along the street network, covering the Shibuya district. The collected Google Street View panoramas resulted in 45,085 photos.

2.Geometrical transformation from GSV to Hemispherical image

We used PSPNet, an image segmentation algorithm, to segment GSV panoramas into sky pixels and obstruction pixels. This allowed us to calculate the dimension of the area exposed to sunlight. The segmented GSV panoramas were then transformed into a hemispherical image.

3.Human exposure to sunlight in street canyon

The above figure shows a geometrical model of the sun and an overlay of the sun’s path in one day on hemispherical images. This model enables us to estimate the volume and location of sunlight depending on the time and day of the year.

4.Results: the spatial distributions of street-level sunlight exposure

The above image shows the results of the shortest path and the minimum sunlight exposure path. Through the random selection process, our result indicates that HIKAGE route decreases 35.23% of the potential sunlight exposure when it takes the shortest path.

HIKAGE FINDER enables us to explore the most suitable routes, considering the volumes of solar radiation.

OPEN STRATEGY

We publish all codes in Github to make your own HIKAGE FINDER for your city. This enables you to collect the relevant datasets and create the algorithm for setting up the app.

https://github.com/xiaojianggis/shadefinder

DESIGN STRATEGY

The HIKAGE FINDER log was designed by Minako Izumi. The design is based on a combination of a crosswalk and a shadow created by a building in Shibuya, which encourages people a imagine urban exploration. The logo should lead people to intuitively grasp the concept and purpose of HIKAGE FINDER, which is to explore and look for shade in the city. The color choice mainly revolves around a blue tone, as it evokes an impression of cool temperatures. However, we can choose from a variety of colors and tones, and consequently, an appropriate design, depending on the situation.

 

 

The symbol “H” appears when the logo is shrunk. This aspect of the design is based on the same design elements and concepts as above.

 

 

PUBLICATION

Li, X., Yoshimura, Y., Tu, W., Ratti, C. (2020). A pedestrian level strategy to minimize outdoor sunlight exposure in hot summer, arXiv:1910.04312

This work is a collaboration between Urban Sciences Lab at The University of Tokyo and Xiaojiang Li, Department of Geography and Urban Studies, Temple University.

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