topic Find nearest point on a line (and M value) in Attribute Rules Questions

Find nearest point on a line (and M value)

ChaimSchwartzIroads — Wed, 08 Nov 2023 21:13:00 GMT

I have a point feature class (BUS_STATIONS), and an M-enabled line feature class (ROADS)

We are trying to build an attribute rule on the BUS_STATIONS feature class, that would populate a field with the M-value of the nearest point of the road. NOTE: I don't want the M-value of the nearest vertex (which could be far away) but rather the nearest portion of the line. What I was thinking to do was the following:

1. Find the coordinates of that nearest point (not vertex) on the line

2. Then find the M-values of the vertex before and after that point and calculate the M value.

But right now I'm stuck with step #1. Any ideas how to achieve that?

Thank you

Chaim

a point feature class, that will populate the M value of the nearest li

Re: Find nearest point on a line (and M value)

MikeMillerGIS — Thu, 09 Nov 2023 11:43:08 GMT

Since you want the calculated M for that location, I am guessing that https://developers.arcgis.com/arcade/function-reference/geometry_functions/#nearestcoordinate will not work?

All the logic you need to get the nearest points and the two bounding vertex to calculate the M is in this rule:

https://github.com/Esri/arcade-expressions/blob/master/attribute_rule_calculation/SplitIntersectingLine.md

Re: Find nearest point on a line (and M value)

ChaimSchwartzIroads — Fri, 24 Nov 2023 09:25:00 GMT

We eventually got it to work, thanks to our amazing developers Eduard and Sara. The logic we use is basically:

1. Calculate the distance between the BUS_STATION point and all the vertices in the adjacent ROAD.

2. For all segments between vertices, calculate the nearest distance from the BUS_STATION to that segment (length of line perpendicular to that segment).

3. Choose the shortest of all outcomes and retrieve the M-value of that point.