Hello:
At https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_Transformers/Transformers/spatialrelations.htm the Pattern Matrix for OGC "Equals" relation is filled with some * characters .
However, Simple Features OGC 06-103r4 document (p. XXXV) at https://www.ogc.org/standards/sfa defines "Equals" relation with no * characters:
a.Relate(b, “TFFFTFFFT”)
To follow OGC specifications, shouldn't the matrix be filled up accordingly?
Thank you very much
Best answer by markatsafe
@pmonteiro I'm not sure what the OGC specification you referenced is trying to tell us - I find that presentation very confusing as I odn't really understand the matrix algebra. But I'm pretty sure Equals is typically thought to be T*F**FFF*. Equals is equivalent to Within & Contains:
WithinT*F**F***
ContainsT*****FF*
EqualT*F**FFF*
Also defined for PostGIS here
@pmonteiro I'm not sure what the OGC specification you referenced is trying to tell us - I find that presentation very confusing as I odn't really understand the matrix algebra. But I'm pretty sure Equals is typically thought to be T*F**FFF*. Equals is equivalent to Within & Contains:
WithinT*F**F***
ContainsT*****FF*
EqualT*F**FFF*
Also defined for PostGIS here
@pmonteiro I'm not sure what the OGC specification you referenced is trying to tell us - I find that presentation very confusing as I odn't really understand the matrix algebra. But I'm pretty sure Equals is typically thought to be T*F**FFF*. Equals is equivalent to Within & Contains:
WithinT*F**F***
ContainsT*****FF*
EqualT*F**FFF*
Also defined for PostGIS here
Thanks Mark.
Googling a bit, found here that OGC definition is not fully compliant with some situations, such as equality between points: the boundary of a Point is by definition empty, whereas OGC states a non-empty intersection between boundaries of equal geometries: TFFFTFFFT.
Better to use T*F**FFF*, then.
Best regards.
