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Up Topic Discussions / LiDAR Support / Unclassified points
- - By murph636 Date 2013-01-27 00:20
I am looking at data in Nicollet County and I notice an overwhelming amount of unclassified points.  Is there a reason there are so many?  They appear to be mostly ground points, but there are unclassified points that appear to be erroneous.
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Parent - By Tim Loesch Date 2013-01-28 17:05
I took a look around and see what you are referring to - I've sent a message to the vendor to get some specifics.
Parent - By Tim Loesch Date 2013-01-31 21:59
I've received an explanation for the number of unclassified points in Nicollet county and the rest of the Minnesota River basin collect.

Data was classified into a number of different classes. The USGS Specification does not allow for the use of the standard Overlap class those points were sent back to class 1 (non ground). The overlap between flight lines was processed so there is a more equal distribution of points and the surface created from bare earth has the same density throughout the project.  This project was collected with 50% overlap so when overlap points are classified that is roughly 50 percent of each individual swath (the outer 25% from each side of the field of view) that gets classed to "overlap".  This makes for a very nice looking data set when making the bare earth surface and products.  Since an overlap class was not delivered those points were assigned to class 1 non ground because they represent all elevations of points from the raw swath.  Also, we ran a building and vegetation macro on the data as requested. The macro did a nice job  but it was not part of the contract to edit those points. When doing this the macro also put points into the class 1 non ground class. This added some more points to class 1. The main contributor is the overlap as  I mentioned above because the project was collected with so much overlap.

hope that helps explain the issue.

tim
Up Topic Discussions / LiDAR Support / Unclassified points

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