Current Oracle Spatial Blog Articles
• Some Oriented Point Functions
• Extracting Inner Rings Changed Ordinate Ordering: A Trap For Players Who Don't Read Documentation!
• PLS-00306: wrong number or types of arguments in call to 'SDO_GEOMETRY'
• Converting Google Earth Formatted Longitude/Latitude points to decimal degrees
• Oracle Business Intelligence Warehousing and Analytics - Spatial Summit
• How far inside, is inside? Measuring actual distance.
• Noding and building a polygon from single, overlapping linestrings
• Analyzing Spatial Query Performance Improvements in Oracle Spatial and Graph 12c Through Cross-Vendor Comparison
• ST_VertexN / ST_PointN - Extracting a specific point from any geometry
• Convert Single Point stored in SDO_ORDINATES to SDO_POINT_TYPE
• Aggregate APPEND Islands and XOR polygons
• Circular Arcs in Geodetic Polygons
• Some SDO_GEOMETRY/DIMINFO handling functions
• Applying And Extending Oracle Spatial - Book Released
• Changing all DIMINFO sdo_tolerance values for all metadata records in one go.
• Building Polygons from Incomplete Linestrings using ST_PolygonBuilder
• Computing Cardinal Directions to nearby geometries
• Intersecting two aggregated polygon layers with SC4O
• Spatial and Oracle 12c
• Update Triggers and SDO_GEOMETRY Equality
• Duplicate Geometry data and Data Models
• CENTROID package update
• How to calculate cumulative length of a linestring
• Useful Package of Wrapper Functions for Sdo_Util.AffineTransforms
• Compute Location from known Lat/Long point using delta easting and northing in miles
• Sorting SDO_GEOMETRY data using the ORDER BY clause of a SELECT statement
• Creating linestrings (2002) from points (2001)
• Rounding Coordinates or Ordinates in SDO_GEOMETRY
• Effects of Sdo_Geometry Ordinate Precision on Performance
• Effects of Sdo_Geometry Ordinate Precision on Storage
• The Spatial filtering of geometries: The effect of tolerances on relationships
• Application of Delaunay Triangulation and Inverse Distance Weighting (IDW) in Oracle for Soils Interpolation
• Selecting all SDO_GTYPE values for all tables/sdo_geometry columns in a schema
• CENTROID package - Tips for Use
• Announcing the Spatial Companion For Oracle (SC4O)
• Filtering Rings (Oracle Spatial)
• Splitting a polygon using one or more linestrings
• isValid, isSimple, Dimension and CoordDim methods for SDO_Geometry
• Line Merging or Collecting lines together: ST_LineMerger
• ST_DeleteVertex for Oracle SDO_Geometry based on Jaspa/JTS
• 3D/4D and SRID aware Conversion functions for SDO_Geometry: WKT and EWKT
• Topological vs Non-Topological Simplification/Generalization of Aggregated Area Geometies in Oracle
• Filtering very short linestrings via bitmap function index
• CENTROID For Oracle
• Gridding a sdo_geometry line/polygon object (Oracle)
• Finding centre and radius of a circular geometry
• Constraining geometry type for sdo_geometry column in a table.
• CASE Statements and SDO_GEOMETRY
• The Power of Constraints and Indexes for Spatial Constraints: stopping duplicate points
• Replacement for SDO_GEOM.RELATE - ST_Relate based on JTS
• Changing Oracle Spatial Index Parameters on existing index
• Writing Excel Spreadsheets files from within the Oracle database using Java and PL/SQL
• Writing xSV (eg csv) files from within the Oracle database using Java and PL/SQL
• A simple spike finder for Spatial/Locator
• JTS Java class compilation for 11g and above
• Random Spatial Search Procedure
• Geometry Snapping using JTS in Oracle
• Exposing JTS's MinimumBoundingCircle functionality
• Exposing JTS's Densifier functionality
• Using JTS's Comparison Functions - HausdorffSimilarityMeasure & AreaSimilarityMeasure with SDO_GEOMETRY
• Free JTS-based Area/Length Functions
• Handy way of systematically fixing polygon geometries with 13349 and other errors
• Standalone CENTROID package now available for download
• Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 4 Processing Geodetic data
• Configurable Buffer: JTS and Oracle
• Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 3
• Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 2
• Free Union, Intersection, Xor and Difference Functions for Oracle Locator - Part 1
• Building Lines into Polygons in Oracle Locator / Spatial
• Finding Intersection Points between Line and Polygon
• Free version of sdo_length
• Alternative to my SQL based GetNumRings function
• External Tables and SDO_Geometry data.
• layer_gtype keyword issue when indexing linear data on 11g
• String Tokenizer for Oracle
• Free Aggregate Method for Concatenating 2D Lines in Oracle Locator 10g
• Reducing 5 Vertex Polygon to Optimized Rectangle
• Square Buffer
• Converting decimal seconds to string
• SDO_GEOM.VALIDATE_GEOMETRY_WITH_CONTEXT - 13356 Issues
• Valid conversion unit values for Oracle sdo_geom.sdo_length()
• Removing Steps in Gridded Vector Data - SmoothGrid for Oracle
• Oracle Spatial DISJOINT search/filtering
• Creating SDO_Geometry from geometric data recorded in the columns of a table
• Concave Hull Geometries in Oracle 11gR2
• Projecting SDO_GEOM_METADATA DIMINFO XY ordinates
• Instantiating MDSYS.VERTEX_TYPE
• New PL/SQL Packages - Rotate oriented point
• GeoRaptor Development Team
• Fast Refreshing Materialized View Containing SDO_GEOMETRY and SDO_GEOM.SDO_AREA function
• Performance of PL/SQL Functions using SQL vs Pure Code
• Implementing the BEST VicGrid Projection in Oracle 10gR2
• Making Sdo Geometry Metadata Update Generic Code
• ORA-13011 errors when using SDO_GEOM.VALIDATE_LAYER_WITH_CONTEXT()
• Extract Polygons from Compound Polygon
• Detecting sdo_geometries with compound (3-point Arcs) segments
• GEOMETRY_COLUMNS for Oracle Spatial
• Convert GML to SDO_Geometry in Oracle 10gR2
• Spatial Sorting of Data via Morton Key
• Swapping Ordinates in an SDO_GEOMETRY object
• New To_3D Function
• Extend (Reduce/Contract/Skrink) Function for Oracle
• Loading and Processing GPX 1.1 files using Oracle XMLDB
• Loading Spatial Data from an external CSV file in Oracle
• Calling the Oracle Spatial shapefile loader from within the Oracle database itself
• Implementing SDO_VertexUpdate/ST_VertexUpdate for Oracle
• Implementing SDO_RemovePoint/ST_RemovePoint for Oracle
• Implementing SDO_AddPoint/ST_AddPoint for Oracle
• ESRI ArcSDE Exverted and Inverted Polygons and Oracle Spatial
• Funky Fix Ordinates By Formula
• Implementing a SetPoint/ST_SetPoint function in Oracle
• Implementing an ST_SnapToGrid (PostGIS) function for Oracle Spatial
• Generating random point data
• Implementing an Affine/ST_Affine function for Oracle Spatial
• Implementing a Scale/ST_Scale function for Oracle Spatial
• Implementing a Parallel/ST_Parallel function for linestring data for Oracle Spatial
• Implementing a Rotate/ST_Rotate function for Oracle Spatial
• Limiting table list returned when connecting to Oracle Database using ODBC
• ST_Azimuth for Oracle: AKA Cogo.Bearing
• Implementing a Translate/ST_Translate/Move function for Oracle Spatial
• Elem_Info_Array Processing: An alternative to SDO_UTIL.GetNumRings and querying SDO_ELEM_INFO itself
• Minumum Bounding Rectangle (MBR) Object Type for Oracle
• How to extract elements from the result of an sdo_intersection of two polygons.
• How to restart a database after failed parameter change
• Fixing failed spatial indexes after import using data pump
• generate_series: an Oracle implementation in light of SQL Design Patterns
• Multi-Centroid Shootout
• Oracle Spatial Centroid Shootout
• On the use of ROLLUP in Oracle SELECT statements
• Surrounding Parcels
• Spatial Pipelining
• Using Oracle's SDO_NN Operator - Some examples
• Converting distances and units of measure in Oracle Locator
• Split Sdo_Geometry Linestring at a known point
• Forcing an Sdo_Geometry object to contain only points, lines or areas
• Unpacking USER_SDO_GEOM_METADATA's DIMINFO structure using SQL
• Generating multi-points from single point records in Oracle Spatial
• Object Tables of Sdo_Geometry
• Oracle Locator vs Oracle Spatial: A Reflection on Oracle Licensing of the SDO_GEOM Package
• FAST REFRESHing of Oracle Materialized Views containing Sdo_Geometry columns
• Australian MGA/AMG Zone Calculation from geographic (longitude/latitude) data
• Loading Shapefiles (SHP) into Oracle Spatial
• Oracle Spatial Mapping and Map Rendering Performance Tips
• The significance of sdo_lb/sdo_ub in USER_SDO_GEOM_METDATA: Do I need it?
• Oracle Spatial Forum - Melbourne April 2007
• Layer_GTypes for spatial indexes
• Oracle's SQL/MM Compliant Types
• Tips and Tricks
Anyone who has used an ESRI client software to edit data which is then stored in Oracle via ArcSDE has probably come across some peculiarly organised polygons that pass ArcSDE validation but not Oracle’s.
These peculiarly organised polygons are inverted or exverted polygons that have their genesis in the original programming of the Spatial DataBase Engine (SDBE) 1.0 by Geomatic Technologies Incorporated (GTI) based in Bellingham, Washington (a company owned by the brilliant Mike Butler) before its sale to ESRI.
I am sure inverted polygons exist in ArcSDE (and have double checked the original “Introduction to ArcSDE” course notes I wrote for ESRI Inc back in 1995) but I cannot remember if exverted polygons were a part of ArcSDE. When I held the position of GIS Manager at my last employer, my team constantly had problems with ArcInfo creating bow tie (ie exverted) polygons which ArcSDE would pass and store in Oracle (we used SDO_GEOMETRY storage) yet would not pass our daily PL/SQL based DBMS_JOB that checked all spatial edits done that day. Because of this I have included discussion of exverted (eg bow tie ) polygons in this article.
OK, since a picture is worth a thousand words, let’s have a look at these polygons.
Firstly, let’s create a table to hold our data.
Now, let’s create a singly inverted polygon.
This polygon looks like this.
Now, let’s create a doubly inverted polygon.
This polygon looks like this.
Now let’s create a simple, exverted polygon.
This polygon looks like this.
Finally, though unnecessary (as the previous exverted polygon is also a “bow tie”), let’s create a classic Bow Tie (exverted) polygon.
This polygon looks like this.
Now let’s check the status of these geometries
Note that all of them are described in the SDO_ELEM_INFO array by a single outer shell (ie 1003). This is correct with respect to the organisation of inverted and exverted polygons. For those not used to Oracle, the error number 13349 is described as follows:
Of course, because they are not OGC/SFS or SQL/MM compliant polygons, they fail Oracle’s validation software.
Now, check what happens when they are passed through Oracle’s own, internal, Sdo_Util.Rectify_Geometry routine.
They are corrected. Normally one would correct these either in the client or in the database via a trigger or a DBMS_SCHEDULER task run at the end of each day to check the day’s edits. Fixing via interactive SQL executed in SQLPlus or SQL Developer would occur as follows:
Whilever these geometries exist in the database uncorrected, what is the effect on geoprocessing results?
First, are buffers correctly formed?
Yes they are. Secondly let’s create a test, overlay geometry.
Which looks like this (over oid = 2):
Firstly let’s union (SDO_GEOM.SDO_UNION) this geometry with the ‘Doubly Inverted Polygon’ (oid 2).
Which (correctly) looks like:
Now let’s intersect (SDO_GEOM.SDO_INTERSECTION) this geometry with the ‘Doubly Inverted Polygon’ (oid 2).
Which (correctly) looks like:
Of course, one should really only conduct geoprocessing on valid geometries, but if you have to do so on invalid geometries, please check the results oneself as Oracle, I believe, does not guarantee the results of processing when the geoemtry data is invalid.
I hope this article is of use to someone.