Merging GPS Points to Polyline

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05-01-2014 12:52 PM
NickUlrich
New Contributor
Hello everyone. I am currently working on a project with a local county, making a fish barrier map represented by stream polyline data. The problem is, the data that was collected were from GPS points taken in the field by a biologist. A lot of these points don't actually fall on the stream, and in most cases are anywhere from 1-100 meters off the polylines. Yet they don't want to actually physically move the points, but rather just bring that data into the polylines. I am having trouble figuring out how to do this, a simple join doesn't work because there are no like fields in the attribute table to join the data with, and I can't run an intersect or merge either since the points and polylines don't actually physically match up. I have been reading up on linear referencing, but can't quite get it to work. Is there any tool in which I could set a 100 meter buffer on all the polylines and then merge all the points that fall in the buffer? Any help or ideas would be appreciated, I hope I didn't make this to confusing :confused:
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2 Replies
JasonScheirer
Regular Contributor II
You could either do a Spatial Join on a specified search radius distance, or more destructively, use the Snap tool to move the points to the polylines.
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RichardFairhurst
MVP Honored Contributor
I would create a route of the stream and use the Locate Features Along Route tool with a radius of about 100 meters.  This will create point events along the rivers, and you can specify whether you want only the closest route or all routes within the radius (I always to the latter with road related points).  No destructive changes to the geometry will be made to either the lines or the points.

There are ways to chain the points into line segment events using standard joins after the point event table has been created.  See this post for an example.  Once the segments between each nearest point pair is created you can use the join to transfer point attributes to assign FROM and TO values of the points to the attributes associated with each segment.  Where the attribute is identical in both the FROM and TO fields the segment can be considered a stretch of the stream with that attribute.  You can then use the Dissolve Route Events tool to join the end to end chain segments into a single continuous line event for each contiguous and unique set of related attribute values.
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