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	Space-Time Cube	時空間カーネル密度推定（ST-KDE）
分野	Human Geography	空間分析
系統	Process / pipeline	Regression model
提唱年	1970	2010 (space-time extension); 1956 (KDE origin)
提唱者	Torsten Hägerstrand (time geography); cube popularized by Menno-Jan Kraak	Nakaya & Yano (space-time formulation); KDE foundation by Rosenblatt and Parzen
種類	Spatiotemporal data structure and visualization framework	Non-parametric density estimation
原典	Hägerstrand, T. (1970). What about people in regional science? Papers of the Regional Science Association, 24(1), 6–21.	Nakaya, T., & Yano, K. (2010). Visualising crime clusters in a space-time cube: An exploratory data-analysis approach using space-time kernel density estimation and scan statistics. Transactions in GIS, 14(3), 223-239.
別名	Hägerstrand Space-Time Cube, Space-Time Aquarium, Spatiotemporal Cube, Time-Geographic Cube	ST-KDE, spatiotemporal kernel density estimation, space-time KDE, 3D kernel density estimation
関連	4	5
概要	The space-time cube is a framework from time geography for representing and analyzing phenomena that move and change over both space and time. Two horizontal axes carry geographic location and a vertical axis carries time, so each observation becomes a point in a three-dimensional x–y–t volume and a moving object traces a continuous 'space-time path' through the cube. Introduced conceptually by Torsten Hägerstrand in 1970 and turned into a practical analytic and cartographic tool by Menno-Jan Kraak, it underpins modern spatiotemporal hot-spot and trajectory analysis.	Space-Time Kernel Density Estimation extends classical KDE into three dimensions — two spatial and one temporal — to reveal how the intensity of point events (crimes, accidents, disease cases) varies continuously across both geographic space and time. It produces a smooth probabilistic surface that highlights where and when events concentrate most densely.