I have been collecting GPS data in the field using a Trimble G series nomad. The collection site is a forested area with moderate tree cover. The features will be exported into a shapefile for further analysis in ArcGIS. However, Following differential correction some of my features are still above the 1m horizontal accuracy I require so I am am manually removing the feature related positions with very high vertical accuracy in an attempt to reduce the effect of multipath errors.

Upon opening the files in PFO I am noticing a large number of not in feature positions (as seen in the attached picture) which are complicating the process as they overlap with the feature related positions upon feature deletion, so I am wondering:

  1. If the these positions are indicative of a methodological misstep in my collection?
  2. what effect, if any these may have on the horizontal accuracy of the features and as such if deleting them is likely to negatively impact the accuracy of the features?

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2 Answers 2


My understanding of these "not in feature positions" is that they're just a "breadcrumb trail" of the rover's position during data collection. I get these too in my data, and from what I can see, they are just single pings that it records every now and then. I see more in areas that I stood in for longer periods of time. I am sure that there is a way to deactivate their creation, but I haven't looked into it because I just ignore them and don't export them.
I have not noticed any negative impact to the accuracy of my actual features


To stop TerraSync from recording "Not In Feature Positions", run TerraSync, select Setup / Logging Settings, and set Between Feature Logging to Style = Time and Interval = Off.

It's possible that your GIS administrator has disabled your ability to mess with this option - I know TerraSync allows users to be locked down for their own good!

If you have an SSF file which contains "not in feature positions" you can remove them easily by editing the file in SSF Record Editor (one of the PFO tools), then selecting Edit menu / Delete Positions outside Features. Once you've done that I recommend doing "Save As", and save the file with a new name, don't save deleted records. If you just Save the SSF file using the original name, the deleted records are still there (marked as deleted) but I've had these deleted positions mysteriously showing up in some tools.

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