SpatialDB Advisor
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Current Oracle Spatial Blog Articles • 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 • SDO_AGGR_SET_UNION • 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 • SURVEY: The Future of GeoRaptor • 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 • SDO2GeoJSON • 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 • GeoRaptor 3.0 Officially released. • 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 • Converting Google Earth Formatted Longitude/Latitude points to decimal degrees • 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
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In my exploration of the possibilities of using Java Topology Suite’s (JTS) robust algorithms with Oracle SDO_GEOMETRY I have moved to expose three methods within JTS’s GeometrySnapper (com.vividsolutions.jts.operation.overlay.snap) class:
The following examples not not exhaust the possibilities in the implementation. I leave it up to you to install try each function on your own data. Note: I do not test geodetic data though the functions to snap geometries through use of sdo_cs.transform are in the package. 1. Snap Two Lines to Each Other This example might be of use with GPS track logs. Before Image
After Image
2. Snap One Line to Another In the first image above, the red line will be snapped to the blue line.
After Image
3. Snap a Point To a Polygon Before Image
After Image
4. Snap a Line To a Polygon Before Image
After Image In this image both the before and after lines are shown.
5. Snap One Polygon To Another Before Image
The gaps between the three “adjoining” vertices are as shown in the following images.
Knowing these gaps we can set a suitable snapping tolerance to bring snap the left polygon to the right one.
The resultant polygon after snapping is shown below. After Image
I think you will agree that this stuff is pretty cool! Well done JTS and Martin Davis! Now, coupled with the JTS PolygonBuilder functionality, and the geometry editing functions in my GEOM package, we have the basis of some pretty useful editing of geometries. Those functions are:
I hope this article is of interest to someone out there.
        
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