Karine Reis Ferreira João Argemiro Carvalho Paiva Gilberto ...

GeoInfo2003

Interface for spatial operations in geographical database

Karine Reis Ferreira

João Argemiro Carvalho Paiva

Gilberto Câmara

GeoInfo 2003

Summary

• Introduction – New generation of GIS and spatial DBMS

– Challenges

– TerraLib

• Goal

• API for spatial operations

– Vector and raster data

• Conclusion and future works

GeoInfo 2003

New generation of GIS

• DBMS (Database Management System) to manage spatial data [Rigaux et al, 2002]– Object-relational DBMS and spatial extension

• Transition from the monolithic systems to Spatial Information Appliances [Egenhofer, 1999] – Small GIS tailored to specific user needs

• Modular and extensible [Voisard and Schweppe,1997] – Support for addition of independent autonomous

systems

GeoInfo 2003

GIS and DBMS

• Use of DBMS to store, manipulate and manage spatial data (descriptive and geometrical data)

– Relational DBMS

� Scheme

� Binary long type (BLOB)

– Object-relational DBMS

� Spatial data types defined by spatial extensions

attributes

GGISIS

DBMS

GeoInfo 2003

Spatial Extension

• Extends object-relational DBMS for treat spatial data:

– Data Model: spatial data types (SDTs)

– Query language: operations and query on SDTs

– Spatial indexing methods (ex. R-Tree) and spatial join

• DBMS + spatial extension = Spatial DBMS

• Oracle Spatial, IBM DB2 Spatial Extender, Informix Spatial Datablade, PostGIS (PostgreSQL) and Spatial Extension in MySQL (release 4.1)

GeoInfo 2003

Spatial Extension

• Oracle Spatial

CREATE TABLE STATES (state_id NUMBER,name VARCHAR2(100)geometry MDSYS.SDO_GEOMETRY);

SELECT ES.state_idFROM STATES ES, RIVERS RIWHERE RI.gid = 234 AND

SDO_RELATE(ES.geometry, RI.geometry, ‘mask=CONTAINSquerytype=WINDOW’)= ’TRUE’;

• Oracle Spatial:

– Spatial data type: SDO_GEOMETRY

– Operators and functions

� SDO_RELATE, SDO_BUFFER, SDO_AREA

– Spatial indexing: R-Tree e QuadTree

GeoInfo 2003

Challenges

• Develop small GIS that:

– supports different DBMS, relational and object-relational

– treats the differences between spatial DBMS

– extends necessary spatial data types for geographical applications, ex. raster data

– provides spatial operations on spatial data types stored in different DBMS

GeoInfo 2003

TerraLib

• Open source GIS software library

• Provides support for the development of:

– Small GIS

� DBMS for manage spatial data

• Support for different DBMS

– Oracle, Oracle Spatial, MySQL, SQL Server, PostgreSQL

GeoInfo 2003

TerraLib

Access

TerraLib

MySQL Driver PostgreSQL Driver

TeDatabase

MySQL Oracle Spatial

PostgreSQL

ADO Driver OracleSpatial Driver

SQLServer

• Interface with DBMS

GeoInfo 2003

TerraLib

• TerraLib data model

TeDatabase

OracleSpatial DriverMySQL Driver

OracleSpatial

MySQL

createPolygonTable(tableName)

GeoInfo 2003

Goal

Development of a generic programming interface or API (Application Programming Interface) for spatial operations in geographical database in the TerraLibenvironment.

GeoInfo 2003

Challenges

• Develop small GIS that:

– supports different DBMS, relational and object-relational

– treats the differences between spatial DBMS

– extends necessary spatial data types for geographical applications, ex. raster data

– provides spatial operations on spatial data types stored in different DBMS

GeoInfo 2003

API for spatial operations

• Function set for spatial operations on geographical data stored in DBMS

• Generic API: supports relational and object-relational DBMS

• Explores spatial extension functionalities

TerraLib

API forSpatial

Operations

Oracle SpatialAccess

MySQLPostgre

SQL

DBMS

Geographic Application

Spatial Operations

Spatial Operations

GeoInfo 2003

API for spatial operations

Intersection

Union

Difference/XOr

calculateDistanceSpatialRelation

NearestNeighbors

Binary

(VD + VD)

MaskZonal-Binary

(VD + RD)

Buffer

ConvexHull

Centroid

calculateLength

calculateArea-

Unary

(VD)

SpatialScalarBoolean

VD: Vector Data RD: Raster Dada

• Vector and raster data

GeoInfo 2003

API – Vector data

DBMS

SELECT *

FROM geomTable

WHERE sigla= “MG”

calculateArea (“MG”)

blob

double Area (TePolygon poly)

TerraLib

(1)

(2)TePolygon

area

• DBMS without spatial extension – TeDatabase

(1) Get geometries from database

(2) Use TerraLib functions to compute operations

GeoInfo 2003

API – Vector data

DBMSOracle Spatial

SELECT SDO_GEOM.SDO_AREA(

geomTable, spatial_data, ...)

FROM geomTable WHERE sigla= “MG”

calculateArea (“MG”)

TerraLib

area

• DBMS with spatial extension

– Oracle Spatial Driver

� Use operators and functions of the spatial extension with SQL language

� Operations are computed by spatial DBMS

GeoInfo 2003

API – Vector data

• SpatialRelation Operation

– Returns the geographical objects which present a specific topological relation

– Topological relation [Egenhofer et al, 1994]

� TeDisjoint

� TeTouches

� TeCrosses

� TeWithin

� TeOverlap

� TeContains

� TeIntersects

� TeEquals

� TeCovers

� TeCoveredBy

GeoInfo 2003

API – Vector data


– DBMS without spatial extension

(1) Gets geometries from database based in their minimal boundary rectangle (MBR)

(2) Uses TerraLib topological functions

GeoInfo 2003

API – Vector data



� Builds a SQL query using the SDO_RELATE operator

� Operation computed by spatial extension

SELECT geomTable1.*

FROM state_polygons geomTable1,

state_polygons geomTable2

WHERE geomTable2.object_id = 'MG'

AND SDO_RELATE(geomTable1.spatial_data,

geomTable2.spatial_data,

'mask = TOUCH querytype=WINDOW')='TRUE'

GeoInfo 2003

API – Vector data

• Buffer Operation

– Generates a new geometry based on a distance to a specific geographical object


Oracle Spatial

SELECT SDO_GEOM.SDO_BUFFER(g.spatial_data, m.diminfo, 1.0)

FROM test_Line g, USER_SDO_GEOM_METADATA m

WHERE m.table_name = 'test_Line'

AND m.column_name = 'spatial_data'

AND object_id = '17'

GeoInfo 2003

API – Vector data


– Generates a new geometry based on a distance to a specific geographical object


Oracle Spatial

SDO_GEOMETRY (2003, NULL, NULL,

SDO_ELEM_INFO_ARRAY (1, 1005, 8, 1, 2, 2, 5, 2, 1, ..., 9, 2, 2),

SDO_ORDINATE_ARRAY (18, 17, 19, 18, 18, 19, 16.4142136, 19,

14.7071068, 20.7071068, 14, 21, ..., 20.7071068)

GeoInfo 2003

API – Vector data


– SDO_GEOMETRY

� Compound polygon: straight line segments (2 points) and circular arcs (3 points).

– TePolygon

� straight line segments (2 points)

GeoInfo 2003

API – Vector data


– Generates a TePolygon from a SDO_GEOMETRY

� TeGenerateArc function

� Generates an arc through 3 points

pt1

spt3 pt2

C(x0, y0)

r� ?�

�

ptnpt1

spt3 pt2

C(x0, y0)

r� ?�

�

ptn

GeoInfo 2003

API – Raster Data

• Zonal Operation

• Calculates statistics of a region or zone of a raster data

GeoInfo 2003

API – Raster Data

• Mask Operation

– Clips a raster data using a mask

GeoInfo 2003

API – Raster Data

• Mechanism to traverse a raster data only in a region inside or outside a specific polygon

• Developed:

– Iterator concept on TeRaster structure

� IteratorPoly

– Route strategies

GeoInfo 2003

API – Raster Data

• Iterator is an abstraction of a pointer to a sequence [Stroustrup, 1999]

• Generic programming: disconnect data structures fromalgorithms

TeCalculateStatistics(itBegin, itEnd, stat)

TeRaster::iteratorPoly itBegin = raster->begin(poly, TeBoxPiIn)

TeRaster::iteratorPoly itEnd = raster->end(poly, TeBoxPixelIn)

TeRaster* rasterData Structure

Iterator

Algorithm

GeoInfo 2003

Conclusions

• Spatial operations are essential in a geographical application

• The developed API:– Provides spatial operations on a high level of

abstraction for the developers of geographical application

– Explores a new generation of object-relational DBMS that manage geographical data

GeoInfo 2003

• Implement other operations on raster data:

– Mathematical Operations

– Reclassify

– Slice

– Weight

• Extend the API to support new spatial extensions

– Spatial Extension in MySQL (release 4.1)

• Use future resources of spatial extensions to treat raster data (ex. Oracle Spacial)

Future Works

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