pointOnLine.location does not return correct distance

[Andi-Lo]

I currently wonder if the @turf/pointOnLine package does return a wrong location value.
Here is a short fiddle of the problem:

http://jsfiddle.net/andi_lo/95q4Lgqc/

I would like to set a point (which is a train station in my project) onto the polyline (representing the routes shape) via turf.pointOnLine and use the returning location property as of how far the train traveled. However if I use turf.along with the distance provided by turf.pointOnLine(...).properties.location I will get a point that does not match my expectations. I would expect to get a point that lays onto the station but I get a point that is positioned falsely.

The used geojson is inside the fiddle. Feel free to ask for clarification if needed.

[DenisCarriere]

@Andi-Lo Thanks for reporting this issue. I've managed to get the result closer to the station point by applying reverse() to the LineString's coordinates, however it's still a bit off, one would assume that doing pointOnLine+ along would result in nearly the same location.

We should try to replicate this behavior in the TurfJS tests.

Example - reverse()

lineString.features[0].geometry.coordinates.reverse();

[DenisCarriere]

Related To-Do on @turf/along: #691

[Andi-Lo]

Thanks for reply,

until it is fixed I will use a workaround (measuring all sub-segments with turfs lineDistance module)

[DenisCarriere]

@Andi-Lo Feel free to send a PR if you do find a solution for the @turf/point-on-line issue you mentioned.

[dpmcmlxxvi]

@Andi-Lo Can you double check that this is resolved with PR #750 so the issue can be closed?

[Andi-Lo]

@dpmcmlxxvi not sure how to validate.

I would need to checkout the turf master branch and get myself a bundled turf.min.js file and include that in my project to see if results are not as expected or is there a faster way?

[dpmcmlxxvi]

@Andi-Lo That's what I do. Check out, install, and build. Then you can use packages/turf/turf.min.js. Not sure if there is a nightly build of the master branch built somewhere online. Maybe @DenisCarriere would know.

[DenisCarriere]

There isn't any nightly builds, however it might be a good idea. The process would need to be automated and be based on the master branch.

[Andi-Lo]

With the latest release I updated the version of my fiddle:

https://jsfiddle.net/andi_lo/95q4Lgqc/

As you can see the result seems now correct to me. Nice work @dpmcmlxxvi !

[DenisCarriere]

👍 Glad it works, definitely nice work from @dpmcmlxxvi