9.34.2. Geometric Objects
Virtuoso supports a wide variety of spatial features that can be represented in WKT or SHP: BOX, BOX2D, BOX3D, BOXM, BOXZ, BOXZM CIRCULARSTRING COMPOUNDCURVE CURVEPOLYGON EMPTY GEOMETRYCOLLECTION, GEOMETRYCOLLECTIONM, GEOMETRYCOLLECTIONZ, GEOMETRYCOLLECTIONZM LINESTRING, LINESTRINGM, LINESTRINGZ, LINESTRINGZM MULTICURVE MULTILINESTRING, MULTILINESTRINGM, MULTILINESTRINGZ, MULTILINESTRINGZM MULTIPOINT, MULTIPOINTM, MULTIPOINTZ, MULTIPOINTZM MULTIPOLYGON, MULTIPOLYGONM, MULTIPOLYGONZ, MULTIPOLYGONZM POINT, POINTM, POINTZ, POINTZM POLYGON, POLYGONM, POLYGONZ, POLYGONZM POLYLINE, POLYLINEZ RING, RINGM, RINGZ, RINGZM
Some less popular types are not yet supported: CIRCULARSTRINGM, CIRCULARSTRINGZ, CIRCULARSTRINGZM COMPOUNDCURVEM, COMPOUNDCURVEZ, COMPOUNDCURVEZM CURVE, CURVEM, CURVEZ, CURVEZM CURVEPOLYGONM, CURVEPOLYGONZ, CURVEPOLYGONZM GEOMETRY, GEOMETRYZ, GEOMETRYZM MULTICURVEM, MULTICURVEZ, MULTICURVEZM MULTIPATCH MULTISURFACE, MULTISURFACEM, MULTISURFACEZ, MULTISURFACEZM POLYHEDRALSURFACE, POLYHEDRALSURFACEM, POLYHEDRALSURFACEZ, POLYHEDRALSURFACEZM POLYLINEM SURFACE, SURFACEM, SURFACEZ, SURFACEZM TIN, TINM, TINZ, TINZM
For the sake of speed and scalability, spatial support has some intentional restrictions, that will probably persist for long time.
--- No support for circumpolar shapes. A ring with a pole inside it or on the border of it may be treated as an error or result in wrong calculations of spatial relations. E.g. the st_intersects of two triangles POLYGON((0 89, 120 89, 240 89, 0 89)) and POLYGON((0 88, 120 88, 240 88, 0 88)) may return FALSE. st_intersects of two triangles POLYGON((0 89, 60 90, 120 89, 0 89)) and POLYGON((120 88, 180 90, 240 88, 120 88)) may also return FALSE. Note that Equator is a circumpolar shape.
--- No support for long orthodromic or near-orthodromic arcs. The implementation assumes that shapes reside inside their bounding boxes so st_intersects of two orthodromic arcs, LINE (0 1, 180 1) and LINE (90 1, 270 1) may return FALSE. However big shapes made of small segments (such as a coastline of Eurasia) will be handled correctly. Shapes that are close to 180 longitude get two sets of bounding boxes, shifted 360 one from another, so relations between Alaska and Chukotka will be calculated correctly no matter what offset is used.
--- In order to deal with weird data sources, the range for longitudes is -270 to -540 and the range for latitudes is -90 to +90 for most cases and -96 to +96 for some features such as bounding boxes. If the parsing of a shape did not report range errors for co-ordinates then there's no warranty that all points are in WGS ranges.
--- Peculiarities like self-touch or self-intersection of polygons can be detected, but no warranties are given.
--- Arcstrings are poorly supported and their support will never be optimized for speed. Each arc is supposed to be no longer than 180 degrees. As a result, ESRI circles that consist of two arcs 180+180 are supported whereas ST_Intersects on "ill" circles like 270+90 may return wrong answers.