Problem with Locate Features Along Route (Linear Referencing)

[toddsams]

Hi,

I am attempting to measure the distance between sites (points; n=50) that were sampled along a trail using the Linear Referencing tools. I created a "route" from my trail feature class (line; dissolved into one single feature) and was able to run the Locate Features Along Route tool without any errors. I then ran Make Route Event Layer so that I could view my points after they had been "snapped" to the trail, which all looked great.

The problem I am having is with the values in the Measure Field, which is supposed to list the distance at which each point exists along the trail. I sorted the Measure Field in descending order and expected that my sites would then be listed in the order in which they appear along the trail, and this is the case for the first 12 sites. However, the 13th site listed is the one at the opposite end of the trail and then the remaining sites are listed in sequential order and meet back up with the 12th site. I checked to see if this could be explained due to the values being measured from the other end of the trail, but this didn't add up.

So basically, it seems that the Measure Field was not calculated properly. I would greatly appreciated any insight into this. Many thanks in advance!

[toddsams]

The smoothed line still has MMONOTONIC = 10 for all records. I built topology and rules for the smoothed line and there were no errors.

Is there something else I can do to ensure monotonicity in the dataset?

[RichardFairhurst]

The smoothed line still has MMONOTONIC = 10 for all records. I built topology and rules for the smoothed line and there were no errors.

Is there something else I can do to ensure monotonicity in the dataset?

10 is an odd result for the MMonotonic calculation.  It should mean that nearly every measure is the identical on every vertice.  Have you looked at the sketch properties of the route to see how many parts it is made up of and how the measures look?  Also you should set the M tolerance and resolution in the environment for the Create Route tool to ensure it has the decimal precision you need (if you use miles and it rounds to whole numbers, most measures will be identical).

So in an edit session open the sketch properties and let me know what you see.

You could also set hatching on the route layer to display the measure layout.

I also want to be sure again that this trail is not complete loop.

Can you screenshot the whole trail just so I understand what you are working with?

[toddsams]

So in an edit session open the sketch properties and let me know what you see.

I'm have an edit session open and selected sketch properties. However, I am not seeing anything listed (image attached). I have not done much editing since Version 3.x and the new editing interface is a bit confusing to me.

There are 368 features that comprise the trail (trail attribute table also attached).

You could also set hatching on the route layer to display the measure layout.

Also not familiar with how to do this.

I also want to be sure again that this trail is not complete loop.


Can you screenshot the whole trail just so I understand what you are working with?

The trail is not a complete loop.

[toddsams]

I had previously ran MMONOTONIC on the trail data (not the trail as a "route"). After running it on the route, I obtain values of either 15 or 9 for each feature.

It does look like there are overlapping lines (9) and other problems (15). I was hoping these had been cleaned up because I checked for errors with topology rules and everything seemed fine.

[RichardFairhurst]

I'm have an edit session open and selected sketch properties. However, I am not seeing anything listed (image attached). I have not done much editing since Version 3.x and the new editing interface is a bit confusing to me.

There are 368 features that comprise the trail (trail attribute table also attached).



Also not familiar with how to do this.



The trail is not a complete loop.

To build the trail you need a single attribute on all segments when building the Create Route.  Having 300+ segments makes no sense for positioning events, since each event will have the same measures, since each segment will restart the measures.  Breaking it apart was only a temporary step to help you clean up the topology, but once that is clean you want to rebuild a single route feature.  Therefore Make id 1 again on all segments and then Create Route with the Length option and the orientation priority using that id.

To see the Sketch properties you have to select a single feature and then edit its vertices.  Right click the single selected feature with the Editor cursor and choose "Edit Vertices" and the sketch table will show up.  Only look at the sketch properties of the route built the way I explained above.

The fact that the original lines were not Routes is why they came up as 10.  Everything was Not a Number so it was all one value.  My logic should probably be altered to make that just an 8, but in any case the fact that there were not polyline M values explains the answer.

To apply hatches, choose a route feature layer (polyline M features) and open the Property window for the layer (right click and choose Properties or double click the layer).  There will be a Hatches tab.  See the help here on setting up hatching.  But only do that after building the route on the combined segments that form a single trail.

[toddsams]

I decided to "trace" over the trail layer and although my new layer does not capture all of the twists and turns of the trail, at least I can get a general sense for the relative difference in distance between the sites along the trail. The Linear Referencing tools and measures calculated just fine after creating the new (clean) line to generate the route with. Someone else gave the original trail data to me and it clearly has bad topology!

Many thanks for all of your help! All of the suggestions you made were helpful.

[RichardFairhurst]

I decided to "trace" over the trail layer and although my new layer does not capture all of the twists and turns of the trail, at least I can get a general sense for the relative difference in distance between the sites along the trail. The Linear Referencing tools and measures calculated just fine after creating the new (clean) line to generate the route with. Someone else gave the original trail data to me and it clearly has bad topology!

Many thanks for all of your help! All of the suggestions you made were helpful.

Glad I could help.  I knew once you had a clean line topology your problems would go away, so I'm glad you worked out a way to get there.