Load Attributes - Load field values from source theme (multiple spatial join)

With this function you can transfer attributes of a source theme to one or several destination themes by joining the themes spatially (the field attributes of the source theme are added to the destination theme according to the spatial relationship of their features). This kind of join is only possible between the themes of the active view.

In opposite to the spatial join of ArcView (where only the field value of the first fitting record is used) the field values of all overlapping features are transferred to separate fields. The new fields are numbered consecutively (e.g. Area1, Area2, Area3 etc.) and the field values are sorted descending by the amount of overlap (e.g. the field values of the largest area or the longest line inside of a polygon are copied to the fields with index 1). This function is very powerful and of multipurpose use (see Examples of use below) and there are many differences to a normal spatial join (see Hints to join attributes).

Warning: Mind that dBASE tables are limited to a maximum of 255 fields. If you load 20 attributes, you can thus create only 12 fields per attribute. If your destination table already has numerous fields, this number decreases further and the function may be stopped with an error message.

Weighting factor: The field values are sorted by the degree of overlap. The calculation of this factor and how the features are related and intersected, depends on the type of the source and destination theme ("buffer" stands for a destination theme of any type that is buffered during calculation):

Source

Destination

Condition for overlap

Weighting factor

Point

Point

coordinate is identically

record number

Point

Line

point is exactly on the line

position along the line

Point

Polygon

point is inside of the polygon

distance to the outline of the polygon

Point

Buffer

point is within the buffer

distance to the outline of the buffer

Line

Point

line contains the point exactly

position along the line

Line

Line

lines are overlapping

length of identical line section

Line

Polygon

line is intersecting the polygon

length of line section within polygon

Line

Buffer

line is intersecting the buffer

length of line section within buffer

Polygon

Point

polygon contains the point

distance to outline of the polygon

Polygon

Line

polygon contains part of the line

length of line section within polygon

Polygon

Polygon

polygons are overlapping

area overlapping with polygon

Polygon

Buffer

polygon overlaps the buffer

area overlapping with buffer

Polygon

=Source

polygons are adjacent

length of the common border line

Adjacent polygons without overlap are normally not considered. If a polygon theme is joined with itself though (destination theme identical to source theme), the adjacent polygons are included and the length of the common border line is used as weighting factor. Polygons that are only connected at a single point are still ignored. Buffer the features to include those neighbors too.

Examples of use:

2003 WLM Klosterhuber & Partner OEG