12 Review and Outlook

Transcription

1 12 Review and Outlook 12.1 Review 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 926

2 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 927

3 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 928

4 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 929

5 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 930

6 What are the characteristics of the vector model? What problems arise during discretization? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 931

7 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 932

8 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 933

9 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 x 1 a 2 e 1 e 3 a 4 Which operations on fields are there? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 934

10 What is a (thematic or topographical) map? Which means for designing maps are there? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 935

11 Why cartographic generalization is necessary at all? What are the basic operations of generalization? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 936

12 How polylines can be smoothed? How does the Douglas/Peucker algorithm work? Why the Douglas/Peucker algorithm does not preserve right angles? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 937

13 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 938

14 Is it possible to evacuate spatial queries with core SQL? On which level SQL is extended in order to become spatial SQL? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 939

15 How to formulate with spatial SQL the query "Through which parcels do brooks flow"? What are the main differences between Oracle Spatial and Postgres? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 940

16 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 941

17 Can conventional B/B+-trees be used for indexing spatial data? How points in the plane are 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 942

18 How does the data-driven point quadtree work? F E C J I D E A I F H C K J B G 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 D i I j B a c f e g j b d h i C d Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 943

19 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 944

20 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 III 3 ADE IV 2 H II 1 IJG IK I 1 2 BCF V Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 945

21 For what purpose XML can be used? What are the main components of a document type definition (DTD)? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 946

22 What concepts to integrating different XML documents are there? What are the advantages of XML schema in contrast to DTDs? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 947

23 For what purpose GML can be used? What are the characteristics of XSLT? What are some important SVG commands? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 948

24 What are the special features of the combination of Postgres 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 949

25 What are the special features of the combination of Oracle Spatial and JDBC? How GML based data can be processed with Java? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 950

26 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 951

27 How photogrammetry can 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 952

28 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 953

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 954

30 What kinds of automotive navigation are there? How does quadtree spatial cloaking work? Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 955

31 How can environmental data be characterized? What are the properties of monitoring networks? aus: Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 956

32 12.2 Outlook ACM Founded in 1947 as The world's first scientific and educational computing society More than 92,000 members (2009) Headquarters in New York City 35 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 957

33 12.2 Outlook Sessions GIS Privacy GeoWeb Road Networks Industrial Session Computational Geometry Spatial-temporal Data Visualization Map Matching and Labeling Spatial Queries Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 958

34 12.2 Outlook Spatial-temporal Data Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 959

35 12.2 Outlook A Lagrangian Approach for Storage of Spatio- Temporal Network Datasets: A Summary of Results Authors: Michael R. Evans, KwangSoo Yang, James M. Kang, Shashi Shekhar URL: Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 960

36 12.2 Outlook Storage of Spatio-Temporal Network problem Input A spatio-temporal network S A set of Operations O Output Data file containing S stored across data pages Objective Minimize data page access for operations O Constraints S is too large for storage in main memory Preserve temporal edge attribute information Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 961

37 12.2 Outlook Challenges : Complexity of incorporating temporal data into the network Careful analysis required to reduce the disk I/O Accessibility of data records is constrained by Network topology Temporal access patterns. Developing partitioning strategies that account for the space-time interaction that occurs between nodes and edges Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 962

38 12.2 Outlook Lagrangian-Connectivity Partitioning (LCP) Key concepts: Non-orthogonal STN partitioning A sub-node database record format Lagrangian use of time-expanded networks for storage. Nonorthogonal Allows temporally connected information, with variable time information, to be stored on a single data page Graph partitioning can be used to divide the network into spatiotemporal groups (Min-Cut) Attempts to capture movement through a spatiotemporal network. Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 963

39 12.2 Outlook Time-expanded network (TEN) Replicates each node along the time set such that a time varying attribute is represented between replicated nodes Capture non-orthogonal access patterns of route evaluation operations Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 964

40 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 965

41 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 966

42 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 967

43 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 968

44 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 969

45 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 970

46 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 971

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 972

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 973

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 974

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 975

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 976

52 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 977

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 978

54 12.2 Outlook Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 979

55 12.2 Outlook Future work Preserving containment relationships Preserving symmetries Spatial Databases and GIS Karl Neumann, Sarah Tauscher Ifis TU Braunschweig 980

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