12 Review and Outlook

Transcription

1 12 Review and Outlook 12.1 Review 12.2 Outlook [TN16] Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 957

2 12.1 Review What are the basic functions of a geographic information system? What are some common names for GIS in diverse areas? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 958

3 12.1 Review What are spatial objects? What are the two main distinctions of spatial objects on basis of their contour? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 959

4 12.1 Review What are the two main models of space? What are the basic concepts of geometry and topology? What are the main topological relationships? spatial field Spatial Framework Attribute Domain spatial reference Object Domain Spatial Embedding Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 960

5 12.1 Review What are the characteristics of the raster model? What are the main compression techniques for raster geometry? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 961

6 12.1 Review What are the characteristics of the vector model? What problems arise during discretization? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 962

7 12.1 Review Which methods for rasterization of vector shapes are there? Which methods for vectorization of raster shapes are there?? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 963

8 12.1 Review What are the main topology models for vector geometry? Which interpolation methods for fields are there? //skagit.meas.ncsu.edu/~helena/gmslab/interp/ Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 964

9 12.1 Review How to intersect vector geometry segments efficiently? a 3 a 1 e 2 e 4 Q (events): T (active segments): x 1, e 3, e 2, a 4, e 4 S 2, S 3 a 2 e 1 x 1 e 3 a 4 Which operations on fields are there? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 965

10 Review What is a (thematic or topographical) map? Which means for designing maps are there? [HGM02] Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 966

11 12.1 Review Why is cartographic generalization necessary at all? What are the basic operations of generalization? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 967

12 12.1 Review How can polylines be smoothed? How does the Douglas/Peucker algorithm work? The Douglas/Peucker algorithm does not preserve right angles. Why? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 968

13 12.1 Review What procedures exist for the transition from polygons to lines? What is the challenge in the placement of text? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 969

14 12.1 Review Is it possible to evaluate spatial queries with core SQL? On which level is SQL extended in order to become spatial SQL? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 970

15 12.1 Review How to formulate with spatial SQL the query "Through which parcels do brooks flow"? What are the main differences between Oracle Spatial and PostgreSQL? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 971

16 12.1 Review What are the two steps in the evaluation of spatial queries? What are the differences between conservative and progressive approximations? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 972

17 12.1 Review Can conventional B/B+-trees be used for indexing spatial data? How are points in the plane ordered according to the Z-order? How good is the Z-order as a spatial index? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 973

18 12.1 Review How does the data-driven point quadtree work? F E C J I A C B D E F G H I K J How does the R-tree work? D A I II A B C D B G K H b a A f c e II g h I j D i B a c f e g j b d h i C d Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 974

19 12.1 Review When does the R-tree become increasingly inefficient as index structure? How in principle does the linear split method work with the R-tree? 9 m e 3,5 g 2 j 11 Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 975

20 12.1 Review What are the characteristics of the K-d tree? What are the characteristics of the BSP tree? What are the characteristics of the Grid File? S S ADE H IJG BCF III IV II I IK V Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 976

21 12.1 Review For what purpose can XML be used? What are the main components of a document type definition (DTD)? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 977

22 12.1 Review What concepts for integrating different XML documents are there? [EE04] What are the advantages of XML schema in contrast to DTDs? <simpletype name="priotype"> <restriction base="positiveinteger"> <mininclusive value="100"/> <maxinclusive value="999"/> </restriction> </simpletype> Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 978

23 12.1 Review For what purpose can GML be used? What are some important SVG commands? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 979

24 12.1 Review What are the special features of the combination of PostgreSQL and JDBC? /** c PGpoint describing * the circle s center r radius of circle */ public PGcircle(PGpoint c, double r) { this(); this.center = c; this.radius = r; } Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 980

25 12.1 Review What are the special features of the combination of Oracle Spatial and JDBC? How can GML based data be processed with Java? XML Parsing Object Based (e.g. DOM) Event Based Push Parsing (e.g. SAX) Pull Parsing (e.g. StAX) Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 981

26 12.1 Review Which are the architectures of geographic information systems? What are the typical functions of a GIS client (GIS server)? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 982

27 12.1 Review How can photogrammetry be characterized? Which kinds of scanner are used in Earth exploration satellites? How does LIDAR work? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 983

28 12.1 Review What are the typical geometric errors in photographic systems? reference plane invisible space invisible space What are the elements of image interpretation? side view Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 984

29 Review How does GPS work? What are the functions of a location transponder? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 985

30 12.1 Review What kinds of automotive navigation are there? How does quadtree spatial cloaking work? [St12] Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 986

31 12.1 Review How can environmental data be characterized? What are the properties of monitoring networks? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 987

32 12.2 Outlook ACM Founded in 1947 as The world's first scientific and educational computing society More than 100,000 members (2014) Headquarters in New York City 37 Special Interest Groups (SIGs) ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 988

33 12.2 Outlook Sessions Ride Sharing Forecasting and Trends Approximation and Incomplete Data Indexing and Query Processing Routing and Path Finding Scene, Labeling and Metadata Maps and Terrains Data Mining and Analysis Sampling and Privacy Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 989

34 12.2 Outlook Spatial-temporal Data Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 990

35 12.2 Outlook An Algorithmic Framework for Segmenting Trajectories based on Spatio-Temporal Criteria Authors: Maike Buchin, Anne Driemel, Marc van Kreveld, Vera Sacristán URL: Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 991

36 12.2 Outlook Trajectory Continuous mapping from a time interval [t0; tn] to the plane (or a higher-dimensional space) Usually represented by a discrete sample of timespace positions Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 992

37 12.2 Outlook Segmentation Aim: obtain segments where movement characteristics inside each segment are uniform in some sense. Useful to understand the behavior of animals from animal trajectories to find and analyze patterns in movement of sports players for content-based motion retrieval tasks. An optimal segmentation of a trajectory is a segmentation into a minimum number of subtrajectories (segments) according to one or more criterion Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 993

38 12.2 Outlook Movement characteristics Speed Heading Velocity Sinuosity Curvature Curviness any combination of such characteristics Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 994

39 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 995

40 12.2 Outlook Characteristics of algorithmic framework Specify criteria formally that should hold for any attribute within each segment of the segmentation No artificial structures like bounding boxes Result is guaranteed to satisfy the criteria and be optimal Algorithmic technique: randomized incremental construction O(n log n) time segmentation for a trajectory with n vertices in many case Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 996

41 12.2 Outlook A Traffic Flow Approach to Early Detection of Gathering Events Authors: Xun Zhou, Amin Vahedian Khezerlou, Alex Liu, Zubair Shafiq, Fan Zhang Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 997

42 12.2 Outlook Detecting gathering events based on human mobility data Given: Spatial framework (grid) Traffic flow between neighboring grids Thresholds for distance, p-value and result size Challenge: Exponential growth of possible event footprints Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 998

43 12.2 Outlook Smart Edge Algorithm Candidate root filter Cells with significant flows within given distance Create index of roots, linked to flows Building G-Graph Dynamic programming Breadth first retrieval G-Graph pruning: Gscore upper-bound Sorted by number of significant incoming flows Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 999

44 12.2 Outlook Case study Trajectories of over taxis in Shenzhen, 08/2013 Grid size 500m * 500m (128 by 64 grids) GPS signal every 40 seconds Flow function: occupied taxis crossing boundaries Baseline: Monthly average traffic flow during same time and weekday Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1000

45 12.2 Outlook Top-5 G-Graphs, 19:30-19:40, 8/16/2013 Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1001

46 12.2 Outlook Experimental evaluation on the efficiency Examine how each design decision impacts the running time Varying number of grids, distance threshold, result size and p-value threshold Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1002

47 12.2 Outlook Optimal and Topologically Safe Simplification of Building Footprints Authors: Jan-Henrik Haunert, Alexander Wolff Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1003

48 12.2 Outlook Simplification of polygonal rings Selecting a subsequence of its original edges The vertices are defined by intersections of consecutive (and possibly extended) edges Aim: minimize the number of all output edges subject to a user-defined error tolerance Problem is NP-hard use integer program (IP) Large, O(m 6 ) constraints (m: number of input edges) Start with O(m) constraints for a smaller running time Add neglected constraints whenever a new solution violates them Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1004

49 12.2 Outlook Requirements R1restricts the creation of new edges Extend or shorten an old edge (at both ends) No turn of its direction R2 means no change of the order of the edges R3 is similar to the bandwidth criterion that is often applied to line simplification R4 ensures the simplicity of the output rings Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1005

50 12.2 Outlook Shortcut Pair of edges in the same original ring. Selecting shortcut (e, f) means that in the solution there will be an edge a that corresponds to e, an edge b that corresponds to f, and no edge that corresponds to an edge between e and f Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1006

51 12.2 Outlook Pairs of consecutive and feasible shortcuts can be infeasible A shortcut violating the constraints with regard to the original edges may still be part of a feasible solution Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1007

52 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1008

53 12.2 Outlook Further cost measures Impact on the area of a building (w area ) Regularity of shapes i.e. angles close to 90 degrees are preferred (w regular ) Difference of edge directions between the original and the simplified building outline (w similar ) Advanced objective function Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1009

54 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1010

55 12.2 Outlook Future work Preserving containment relationships Preserving symmetries Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1011

56 Spatial Databases and Geographic Information Systems Karl Neumann Sarah Tauscher Institut für Informationssysteme Technische Universität Braunschweig

57 Summer Semester 2017 Lecture "Relational Database Systems 2" Lecture "Information Retrieval and Web Search Engines" Lecture "Information Discovery" Lab "Integrity Constraints" Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1013

58 Lab "Integrity Constraints" Database for OSM data of Braunschweig Syntax and semantic analysis of assertions Generate "suitable" PostgreSQL triggers and functions Display "wrong" data graphically Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 1014