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Why over and undercounts spatial join points to line?

Question asked by BFosberg on Sep 18, 2020

I am seeking to join points to lines (Street segments). I have tried intersect, closest with and without search distances.

I have snapped the points to the lines and run without snapped points.

All joins are 1 to 1 Search distances vary when using Intercept. 

in the most recent case a join of 42,000 snapped points yielded a join count of over 66,000

Running the same points, pre-snapped means I must use a search distance. Results are  order of magnitude over counts or under counts and nothing in between.

Closest yielded join counts of 1 on every line or an 84,000 count total - against a 42,000 possible.

Using Pro 2.6

I made wild guesses at other possible join operation and get other strange results.


We think one cause of errors are points that lay at the juncture of two or more street segments. Why does the 1 to 1 rule not apply?




Update: using Arc desktop 10.5 and snapped points I get within 1% of the correct join count