Citation

Zhao B, Sui DZ, Li Z. Environ. Plann. A 2017; 49(5): 977-979.

Copyright

(Copyright © 2017, SAGE Publishing)

DOI

10.1177/0308518X16685885

PMID

unavailable

Abstract

Compared with the growing worldwide social acceptance of the lesbian, gay, bisexual, and transgender (LGBT) community (Brown and Knopp, 2008; Ferreira and Salvador, 2015; Gates and Ost, 2004), discussions of LGBT-related matters are still a taboo in China. To raise public awareness of this community, we aim to estimate the distribution of gay people in Beijing using location-based social media (LBSM) feeds. To do that, we collected the gay population data from a popular LBSM app - Jack'd. As an app dedicated to gay social networking, Jack'd primarily attracts the use of gay people. A user who launches the location-based function will leave a geolocation (in the format of a pair of coordinates) in the Jack'd database. On 28 September (Wednesday) 2016, we retrieved the geolocations of active users every 6 hours from the Jack'd database via an API (Burrell et al., 2012). As a result, we had 5209 users at 00:00, 1006 users at 06:00, 4972 users at 12:00, 55431 users at 18:00, and 5214 users at 00:00 of the next day. For each sample, we created a fishnet-grid map layer through aggregating the geolocations into equal area hexagons (each edge of the hexagon is 300 meters in length) by QGIS. By ordering these five map layers into a time sequence, we transformed the layers into several space-time volume elements (voxels) by Voxler. The voxels were rendered in a rainbow-like color ramp using a ray-casting algorithm (Roth, 1982). This algorithm simulates the mechanism of a ray travelling from the eye of an observer to the observing object. Here, an observing object is modeled by a system of numerous tiny points. The ray, cast from the eye of the observer, travels through the points. Only the points along the rays are visualized. This algorithm can represent a much clearer texture of a voxel (Hoang et al., 2016). Moreover, in order to illustrate the core portion of the gay community, we visualized a set of net surfaces made by points of an equal value (seven users per sampling unit in space-time). And, a base layer of Beijing city (created in QGIS) was overlaid on the bottom of the voxels; the axes and labels were post-processed in Adobe illustrator...

Language: en