Space time Prisms, I Wish I Knew How to Quit You

Transcription

1 Space time Prisms, I Wish I Knew How to Quit You Harvey J. Miller Department of Geography and The Ohio State University M: miller.81@osu.edu W: u.osu.edu/miller.81

2 Time geography- A love story I have a long romance with time geography 2

3 Space-time prisms What are space-time prisms? Envelope of all possible space-time paths between two locations and times given maximum speed and stationary time Accessibility or sampling error Both are critical for mobility science Hägerstrand T (1970) Papers Regional Science Association, 24,

4 Space-time prisms Why are prisms so fascinating? Beauty: Intuitive and pleasing geometry Elegance: Explains much with little Robust: Wide range of applications Sensitive: Individualistic, social differences Ecological: Links individual to aggregate Practical: Location-aware technologies, mobility data Fractal-like: Endlessly fascinating properties! 4

5 From static aggregates to dynamic individuals A fundamental change in many fields Transportation, social sciences, public health, environmental science, animal ecology, Why? Its how things work! Human/physical systems are complex More data and computation Space-time prisms Lenntorp B (1999) GeoJournal Rainham D, McDowell I, Krewski D, Sawada M (2010) Social Science and Medicine, 70, Neutens T, Schwanen T, Witlox F (2011) Transport Reviews, Ellegård K, Svedin, U (2012) J Transport Geography, 23, Kwan MP (2013) Annals AAG, 103,

6 A galaxy of prisms! Planar prisms Network prisms Field prisms Kinetic prisms Prism intersections Hybrid prisms 6

7 Planar prisms Analytical prisms Spatial extent at a moment in time Easy to describe mathematically Easy to compute Applications Time geographic queries Analytical measures Spatial error Miller HJ (2005) Geographical Analysis, 37,

8 Prism error Error in prism parameters Anchors, time budget, max speed, stationary time Strategies Monte Carlo simulation Spatial error propagation Reliable/rough prisms Hall RW (1983) Transportation Research B, 17B, Kobayashi T, Miller HJ, Othman W. (2011) J Geographical Systems, 13, Delafontaine M, Neutens T, Van de Weghe N (2011) IJGIS, 25, Chen BY, Qingquan L, Wang D, Shaw SL, Lam WHK, Yuan H, Fang Z (2013) Annals AAG, 103,

9 Spatial networks Network time prism Prism subject to network space, speed, connectivity Alibi query Do two prisms intersect? Where and when? Miller HJ (1991) IJGIS, 5, Kuijpers B, Othman W (2009) IJGIS, 23, Kuijpers B, Grimson R, Othman W (2011) IJGIS, 25, Neutens T, Van de Weghe N, Witlox F, De Maeyer P (2008) J Geographical Systems, 10,

10 Velocity fields Field-based prisms Velocities vary across space Why? Urban Fields Dual representation (object, field) High-resolution networks Off-network travel (terrain, air, water) Angel S, Hyman GM (1970) Urban Fields. London: Pion Miller HJ, Bridwell SA (2009) Annals AAG, 99, Downs JA, Horner, MW (2014) EP-B, 41, Liu X, Yan WY, Chow JYJ (2015) J Transport Geography, 42,

11 Kinetics Prisms are physically impossible! Assume instantaneous acceleration & deceleration Kinetic paths and prisms Obey physical limits on acceleration & deceleration Easy to solve in 1D Not easy to solve in 2D Kuijpers B, Miller HJ, Othman W (2011) ACM SIGSPATIAL Long JA, Nelson TA, Nathoo FS (2014) IJGIS, 28,

12 Prism intersections Social interaction potential Prism-prism intersections Where/when for contact & interaction SIP and social outcomes Social networks, social capital, social mobility, Neutens T, Schwanen T, Miller HJ (2010) GA, 42, Farber SA, Neutens T, Miller HJ, Li X (2013) Annals AAG, 103, Widener MJ, Farber SA, Neutens T, Horner MW (2013) Health and Place, 21,

13 Hybrid space Prisms and ICTs Information / Communication Technologies Strategies Implicit ICT: Relations between paths, prisms Explicit ICT: Temporal events generated through interactions with ICT Hybrid prisms: Physical + virtual space Miller HJ (2005) EP-B, 32, Yu H (2006) CaGIS, 33, 3-19 Shaw SL, Yu H (2009) J Transport Geography Couclelis H (2009) EP-A, 41,

14 Prism interiors are heterogeneous Visit probabilities, speeds Strategies Stochastic process: RW, Brownian, Markovian Spatio-temporal interpolation: KDE Why? Environmental impacts: Energy, emissions, GHG Animal movement ecology Prism interior Winter S, Yin ZC (2010) IJGIS, 24, Winter S, Yin ZC (2011) Geoinformatica, 15, Downs JA (2010) GIScience 2010, LNCS 6292, Song Y, Miller HJ (2014) IJGIS, 28, Song Y, Miller HJ, Zhou X, Proffitt D (2015) GA, in press 14

15 Much has been accomplished! But there is more to be done What s left? Heuristics/approximations for error Prism summaries and comparisons Multiscale dynamics Scalability Locational privacy Applications across a wide range human and physical phenomena 15

16 Thank you! (and you too, Prof. Hägerstrand!) Contact Web: u.osu.edu/miller.81 Lund, Sweden November