Oracle Spatial and Mapviewer Problems From Real World Applications

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Oracle Spatial and MapviewerProblems From Real
World Applications
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Oracle Spatial Capabilities
Spatial Analysis
Spatial Data Types
Spatial Indexing
Fast Access to Spatial Data
All Location/Spatial Data Stored in the Database
Spatial Access Through SQL
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Manage ALL Geospatial Data Types
Networks (Connectivity)
Parcels (polygons)
Locations (points)
Data
Imagery (Raster)
3D data (models, LIDAR)
Structured Networks/Boundaries (persistent
topology)
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ltInsert Picture Heregt
Some Interesting Problems From The Commercial
World
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Network Partitioning
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Network Data Model

• Data Model
• Store network (graph) structure in the database
• Maintains connectivity of the network
• Attributes at link and node level
• Network Analysis Functions
• Traditional network algorithms are based on main
  memory
• Need new approaches to deal with large networks
  that are too big to fit into main memory

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Load On Demand Analysis

• Supports load-on-demand approach for very large
  networks
• Networks are logically partitioned
• Each sub-network is small (thousands of
  nodes/edges)
• Sub-networks are incrementally loaded into memory
  as needed for analysis
• Partitioning utilities are available for
  partitioning large spatial networks

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Spatial Network Partitioning
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Logical Network Partitioning
Very Large networks (few hundred million
nodes/links) Updates to the data are common
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Automated Generation of 3D data
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SDO_GEOMETRY for 3D Data

• Points
• Lines
• Simple Surfaces
• All points of a surface lie in a 3D plane
• A 3 point 3D polygon is the simplest surface
• A simple surface can have any polygonal shape
• Composite surfaces
• has one or more connected simple surfaces
• It can be closed or open
• The simple surfaces in a composite surface cannot
  cross each other
• surface of a cube is an example of a composite
  surface
• Cube has six simple surfaces
• Each simple surface is a 3D square

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SDO_GEOMETRY for 3D Data

• Simple Solids
• Solids are composed of closed surfaces
• It has to have one outer surface and one or more
  interior surfaces
• Cube is an example of a simple solid
• A pyramid is another example of a simple solid
• Composite Solids
• Consists of n simple solids as a connected solid
• Can be represented as a simple solid with a
  composite surface
• Topologically there is an equivalent simple
  solid, but the composite solid representation is
  easier
• Example A building composed of rooms
• Simple, composite solids
• Always define a single contiguous volume

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3D Data Extraction

• Extract faces of buildings
• Generation of valid 3D objects from primitive
  elements
• Generating a valid multi-surface from a set of
  planar polygons
• Generating a valid solid/multi-solid from a set
  of planar polygons

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3D Extrusion

• Extruding 2D foot-prints to valid 3D objects

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Generalization in 3D
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City GML Example

• Start with building models generating using CAD
  data
• Generate generalized views of the data for large
  volumes of data (city models)

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Map Generalization
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Map Simplification with Multiple Layers

• Mapshaper.org

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Managing Very Large TINs
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TIN Triangulated Irregular Network

• What is a TIN?
• Vector-based topological data model used to
  represent terrain/surface
• Contain a network of irregularly spaced triangles
  
• 3D surface representation derived from
  irregularly spaced points
• Each sample point has an x, y coordinate and a z
  value or surface value

Node No X Y Z
1 5 6 3
2 3 6 5
3 1 5 6
4 4 4 4
5 6 5 3
6 2 2 2
. . . .
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Disk based TIN Generation

• Many main memory algorithms for creating TINs
• These algorithms do not scale for very large
  number of points
• Constrains add additional complexity
• Break lines, stop lines
• Void polygons

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Grid based TIN Generation