# Spatial Match Behavior

The behavior of the Spatial Match tool depends on the intersection method selected (Intersects, Contains, or Within) and the types of objects being tested. The tables below list the various combinations.

## Intersects

A Spatial Object | Intersects A | If | The Type of the Returned Intersection Object (If Requested) |
---|---|---|---|

Polygon | Polygon | The polygons share any area. Touching edges without overlap is not considered an intersect. | Polygon |

Polygon | Line | The line touches the edge or interior of the polygon. | Polyline |

Polygon | Point | The polygon contains the point. | Point |

Line | Line | Any part of the lines cross each other or share endpoints. | Point Lines might intersect at multiple points, in which case 1 point is returned and a warning is issued. |

Line | Point | The point is a vertex of the line. Note: A line might cross over a point geometrically without a vertex there, and this is not counted as an intersection. | Point |

MultiPoint | Any Object | If it intersects any of the points. | MultiPoint |

Point | Point | The points are the same. | Point |

## Contains and Within

A Target | Contains a Universe | If... |
---|---|---|

Polygon | Polygon | 99.99% of the second polygon's area lies inside the first polygon. |

Polygon | Line | 99.99% of the length of the line lies inside the polygon. |

Polygon | Point | The point is inside the polygon. |

Polygon | MultiPoint | All the points are in the polygon. |

Line | Polygon | Never |

Line | Line | Every segment (for example, 2-point series) in the contained line also appears in the containing line. Segments consisting of the same 2 points in the opposite order (in other words, coded in the opposite direction) still match. Lines that follow the same route geometrically might still not match if one uses more (unnecessary) points. |

Line | Point | The point is a vertex of the line. A line might cross over a point geometrically without a vertex, and the line is not counted as containing the point. |

Line | MultiPoint | All the points are vertexes of the line. |

MultiPoint | MultiPoint | All the universe points are in the target. |

MultiPoint | Point | One of the points are in the MultiPoint. |

MultiPoint | Polygon or Line | Never |

Point | Polygon | Never |

Point | Line | Never |

Point | Point | The points are the same. |

## Spatial Index

If specifying a Calgary (cydb) file, be aware that the Calgary spatial index uses 5 decimal places of accuracy for compression and speed. The YXDB spatial index uses 6 decimal places. This adds an additional round-off error of up to a maximum of 1.8 feet to Calgary indexes. In other words, it is possible that a point can be 1.8 feet inside of a polygon and be found as outside in Calgary.