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Current Oracle Spatial Blog Articles

    Create Polygon From Bearings And Distances
    Function That Returns a Compass Point From a Whole Circle Bearing
    Playing around with Centroids by using different seed values
    GeoRaptor 4.x Update 2
    Simple Oracle C Sprintf or Java String.format
    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
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    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
    SDO_AGGR_SET_UNION
    Sorting SDO_GEOMETRY data using the ORDER BY clause of a SELECT statement
    Creating linestrings from points
    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
    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
    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
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    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
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    Split Sdo_Geometry Linestring at a known point
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    Unpacking USER_SDO_GEOM_METADATA's DIMINFO structure using SQL
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    Object Tables of Sdo_Geometry
    Oracle Locator vs Oracle Spatial: A Reflection on Oracle Licensing of the SDO_GEOM Package
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    Oracle Spatial Mapping and Map Rendering Performance Tips
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    Oracle Spatial Forum - Melbourne April 2007
    Layer_GTypes for spatial indexes
    Oracle's SQL/MM Compliant Types
    Tips and Tricks

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All Blog Articles, Data Models and Free Source Code by Simon Greener, The SpatialDB Advisor is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

ESRI ArcSDE Exverted and Inverted Polygons and Oracle Spatial

Monday February 16 2009 at 03:24

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.

(Note: Both products are OGC Simple Features Specification compliant. So why is this? In the main this is because ESRI’s ArcSDE pre-existed the OGC and SQL/MM standards. It would seem to me that the standards compliance process only tests a product’s adherence to the declared aspects of the standard: they do not look at support for features or functions not declared as part of the standard. Nor do they demand that features not in the standard be removed. This could be construed as being a loop-hole allowing vendors to “embrace and extend” the standard, but in this situation it is simply a case of something historically pre-existing the standard.)

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.

(As side node: GTI produced SDBE only for Interbase. One of the main features of Interbase was an Array datatype which GTI used to store the coordinates of a spatial feature in the POINTS column of the Fnnn table. When ESRI bought SDBE and ported it to Oracle they decided to store the points in a LONG RAW column making it impossible for a non-ArcSDE client to access and understand without some effort at reverse engineering. PL/SQL has no functions that allow a programmer to see “inside” a LONG RAW based SDEBINARY geometry.)

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.

drop   table inverted;
delete from user_sdo_geom_metadata where table_name = 'INVERTED';
commit;
create table inverted (
  oid integer, 
  geom_type varchar2(25), 
  geom sdo_geometry
);
insert into user_sdo_geom_metadata (table_name,column_name,diminfo,srid)
values ('INVERTED','GEOM',MDSYS.SDO_DIM_ARRAY(MDSYS.SDO_DIM_ELEMENT(X,0,5000,0.05),MDSYS.SDO_DIM_ELEMENT(Y,0,5000,0.05)),NULL);
commit;

Now, let’s create a singly inverted polygon.

insert into inverted values(1,'Singly inverted polygon',
sdo_geometry(2003,null,null,
  sdo_elem_info_array(1,1003,1),
  sdo_ordinate_array(100,0,400,0,400,150,250,100,250,200,400,150,400,300,100,300,100,0)));

This polygon looks like this.

Polygon with inverted outer shell

Now, let’s create a doubly inverted polygon.

insert into inverted values(2,'Doubly inverted polygon',
sdo_geometry(2003,null,null,
  sdo_elem_info_array(1,1003,1),
  sdo_ordinate_array(450,0,800,0,800,150,725,100,650,150,575,100,500,150,575,200,650,150,725,200,800,150,800,300,450,300,450,0)));

This polygon looks like this.

Polygon with doubly inverted outer shell

Now let’s create a simple, exverted polygon.

insert into inverted values(3,'Exverted Polygon',
sdo_geometry(2003,null,null,
  sdo_elem_info_array(1,1003,1),
  sdo_ordinate_array(125,400,200,400,200,450,275,425,275,475,200,450,200,525,125,525,125,400)));

This polygon looks like this.

Polygon with exverted outer shell

Finally, though unnecessary (as the previous exverted polygon is also a “bow tie”), let’s create a classic Bow Tie (exverted) polygon.

insert into inverted values(4,'Bow Tie',
  sdo_geometry(2003,null,null,
  sdo_elem_info_array(1,1003,1),
  sdo_ordinate_array(400,400,575,475,725,400,725,550,575,475,400,550,400,400)));
commit;

This polygon looks like this.

Polygon with exverted outer shell - A classic bow tie

Now let’s check the status of these geometries

select i.oid,
       i.geom_type,
       substr(sdo_geom.validate_geometry(i.geom,0.5),1,6) as valid,
       i.geom.sdo_elem_info
  from inverted i;

OID                    GEOM_TYPE                 VALID  GEOM.SDO_ELEM_INFO
---------------------- ------------------------- ------ ------------------
1                      Singly inverted polygon   13349  NUMBER(1,1003,1) 
2                      Doubly inverted polygon   13349  NUMBER(1,1003,1)
3                      Exverted Polygon          13349  NUMBER(1,1003,1)
4                      Bow Tie                   13349  NUMBER(1,1003,1)

4 rows selected

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:

Oracle Error 13349 produced by Sdo_Geom.Validate_Geometry

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.

select geom_type,
       substr(sdo_geom.validate_geometry(geom,0.5),1,6) as ovalid,
       r.geom.sdo_elem_info as oelements,
       r.rectgeom.sdo_elem_info as relements,
       substr(sdo_geom.validate_geometry(r.rectgeom,0.5),1,10) as rvalid
  from (select i.geom_type,
               i.geom,
               sdo_util.rectify_geometry(i.geom,0.5) as rectgeom
          from inverted i )r;

GEOM_TYPE                OVALID OELEMENTS          RELEMENTS                            RVALID 
------------------------ ------ ------------------ ------------------------------------ ------
Singly inverted polygon  13349  NUMBER(1,1003,1)   NUMBER(1,1003,1,13,2003,1)           TRUE
Doubly inverted polygon  13349  NUMBER(1,1003,1)   NUMBER(1,1003,1,13,2003,1,23,2003,1) TRUE 
Exverted Polygon         13349  NUMBER(1,1003,1)   NUMBER(1,1003,1,9,1003,1)            TRUE
Bow Tie                  13349  NUMBER(1,1003,1)   NUMBER(1,1003,1,9,1003,1)            TRUE

4 rows selected

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:

update inverted i
   set i.geom = sdo_util.rectify_geometry(i.geom,0.5)
 where sdo_geom.validate_geometry(i.geom,0.5) <> 'TRUE';

Whilever these geometries exist in the database uncorrected, what is the effect on geoprocessing results?

Let’s check.

First, are buffers correctly formed?

select oid,
       geom_type,
       sdo_geom.validate_geometry(sdo_geom.sdo_buffer(i.geom,10,0.05),0.5) as bValie 
  from inverted i;

OID                    GEOM_TYPE                 BVALIE
---------------------- ------------------------- ------
1                      Singly inverted polygon   TRUE
2                      Doubly inverted polygon   TRUE
3                      Exverted Polygon          TRUE
4                      Bow Tie                   TRUE

4 rows selected

Yes they are. Secondly let’s create a test, overlay geometry.

insert into inverted values(5,'Overlay Geometry',
sdo_geometry(2003,null,null,
  sdo_elem_info_array(1,1003,1),
  sdo_ordinate_array(423,-87,880,-98,867,119,429,158,423,-87)));
commit;

Which looks like this (over oid = 2):

Polygon overlaying Doubly Inverted Inverted Polygon

Firstly let’s union (SDO_GEOM.SDO_UNION) this geometry with the ‘Doubly Inverted Polygon’ (oid 2).

select i1.oid,
       sdo_geom.validate_geometry(sdo_geom.sdo_union(i1.geom,i2.geom,0.05),0.05) as uValid
  from inverted i1,
       inverted i2
 where i1.oid = 2
   and i2.oid = 5;

OID                    UVALID
---------------------- ------
2                      TRUE 

1 rows selected

Which (correctly) looks like:
Union With Double Inverted Polygon

Now let’s intersect (SDO_GEOM.SDO_INTERSECTION) this geometry with the ‘Doubly Inverted Polygon’ (oid 2).

select il.oid,
       sdo_geom.validate_geometry(sdo_geom.sdo_intersection(i1.geom,i2.geom,0.05),0.05) as intValid
  from inverted i1,
       inverted i2
 where i1.oid = 2
   and i2.oid = 5;

OID                    INTVALID
---------------------- --------
2                      TRUE 

1 rows selected

Which (correctly) looks like:

Intersection With Double Inverted Polygon

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.

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Comment [1]

Hi Simon,

Great article. We at Safe have seen these issues confound customers for many years now as they use FME to load data into SDE – typically such features are “rejected” and then we help them do things like run self-intersections to clean them up. There are also issues on older SDE installations (or modern ones using single precision) due to the precision issues that used to be present — these could cause inverted polygons where they weren’t originally — we created the http://www.fmepedia.com/index.php/ArcSDEGridSnapper to help folks detect this early.

Anyway, great article. And now I know how to apply a Myers-Briggs personality test to a polygon (oops, that was inverted not introverted…)

Dale

Dale · 17 February 2009, 05:19 · #