Polyline measuring

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02-13-2019 06:20 PM
DavidEastman
New Contributor II

Hey All,

Hoping someone in this community could help with a distance problem, it seems like the logical place to come, as I'm guessing you have the same requirement for pipelines. (i.e. how long is my pipeline) 

I'm trying to measure a trail in ArcGIS Pro (for a trail running race) and wondering what the actual difference is with the methodologies to measure distance. I can't seem to find a description in the help doco.

We have a 160km race (100 miles) over a large varity of mountainous terrain (www.brisbanetrailultra.earth).

For the polyline that describes the course:

  • I have a shape length at 158km
  • From 3D Analyst I can use the "Add Z Information" and it populates Length3D at a value of 160km (after doing an "Update Feature Z" and - the line has a vertex every 10m)
  • From 3D Analyst I can use the "Add Surface Information" and get a length of 163km (same elevation source as the surface).

My first question is – What’s the difference between the two 3D Analyst methods? Which one is 'more correct'?

  • (Using software in the running community (Garmin; Trace de Trails; etc) we get 160km).

My second question is a little more of serious - something that I need to resolve. I need to place a marker on my maps every 5km. Using the 'Generate Points Along Lines' for the Data Management Tool Box, I can quickly do this, the result however appears to be that the interval is based on the Shape Length! So the result I get is that the last marker on the course at 155km is 3km from the finish line instead of the 5km it’s supposed to be (or 8... if it was using Surface Length).

Hope you can help – this is driving me nuts trying to work it out!

Thx

David

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