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NeilRick
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My office is relatively new to the GPS marketplace and so we are trying to determine an appropriate field procedure for GPS work.  We are currently using Topcon Hiper V equipment, and use Carlson SurvCE in our mini and Carlson Survey for drafting.  Currently, we are starting a procedure where upon arrive on the job site we will set two control points using a MiFi and connected to our state plane coordinates.  We then determine we will set up a Base Receiver over one of those coordinates and configure using the point number.  We can then double check the coordinates for the second control point for tolerance acceptance, and any other control we have on the property.

We will then continue around the property and shoot in corners, roads, etc.

Does this seem appropriate, and will this procedure, once processed and adjusted using the SurvNET program in Carlson, keep our coordinates in state plane coordinates?  In the past we have set up using Read GPS (unknown points), and then localized on the MiFi/State Plane points.  When doing this, after the adjustment process, if we returned and shot only using the Rover and not setting up and localizing, the points would differ by around 6-15 feet (it is my understanding this is because we did not set the Base over a known State Plane point).

Thank you for all your help and suggestions.

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bama7x57
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"Currently, we are starting a procedure where upon arrive on the job site we will set two control points using a MiFi and connected to our state plane coordinates.  We then determine we will set up a Base Receiver over one of those coordinates and configure using the point number.  We can then double check the coordinates for the second control point for tolerance acceptance, and any other control we have on the property.

We will then continue around the property and shoot in corners, roads, etc."

 

This is the method I have used since about 2001. It works well.

I have returned to projects years later and easily reproduce my results. I have shared coordinates on section corners with other surveyors and they have checked and matched my results.

It's a good idea to check into a NGS monument with good horizontal to confirm you have your data collector settings correct.

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Nate The Surveyor
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Do you know what bearings you are on?

Nate

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NeilRick
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So, we turn on the vectors from the Base to the Rover.  Is that what you mean?  So, we have the vectors from the Base in order toe adjust the points.

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Nate The Surveyor
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Posted by: NeilRick

So, we turn on the vectors from the Base to the Rover.  Is that what you mean?  So, we have the vectors from the Base in order toe adjust the points.

No, it's a little bigger than that.

It's the theoreticaly perfect north, that your particular "grid" is based on. You can use any north you want... Within some reason. And, you can make your gps do it. 

Some folks in the early days used "true north by gps". Problem is that true north is no longer true north. If you move east or west. True north is a series of converging lines, in the northern hemisphere. So, really, there is no such thing as true north, without telling us WHERE it's true. Move 1/4 mile east, or west, and you are not on true north. The lines that point at the north pole are converging. True north is ambiguous, without telling us WHERE it's true. We're surveyors. We get hired, to remove ambiguity, not inject into the title chain.

Nate

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Nate The Surveyor
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Are you applying theta, or not?

I've used Carlson data collector before. As I remember, you have an option to use state plane grid, or ground. Are you using either of those? 

I used to use ground, THEN apply theta. To get Grid brngs, ground scale, at the base.

In an attempt to make field crew feel like kings, some of the calculations are hidden. This has the bad effect of hiding important metadata. 

I've not used Carlson in years, so I'd hazard a guess that it has changed some... But I don't know for sure.

I've migrated to Javad, and it gives me metadata, as I like.

N

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spledeus
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Run least squares by any chance?

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NeilRick
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I did see the ground to grid option today.  I will look into that.

We run the lease squares data and that seems to be when the error occurs.  When I run the unadjusted coordinates into the software it matches up the the MiFi Rover shots, but once adjusted it goes off around 9 feet.  Not sure why.

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JKinAK
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Posted by: NeilRick

I did see the ground to grid option today.  I will look into that.

We run the lease squares data and that seems to be when the error occurs.  When I run the unadjusted coordinates into the software it matches up the the MiFi Rover shots, but once adjusted it goes off around 9 feet.  Not sure why.

Don't take this the wrong way but you would be smart to get some formal training.

The knowledge of the forum is great but you need to understand what's going on from the theoretical level on up... and it's highly unlikely that this is the place that you'll get the thorough foundation needed to develop sound processes, debug problems, and reliably deliver what your client needs.

Without that foundation, you'll have lots of sleepless nights wondering if your data is valid or not...

This isn't meant to discourage you - it's to point you towards hooking up with a good trainer for 3 or 4 week long sessions where you get to explore the topics being mentioned here. While that sounds like a big investment - it's nothing compared to the stress and cost of seeing poured concrete curing in the wrong location.

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Bill93
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Doesn't the least squares report tell you what measurement is in conflict with the rest to give such a discrepancy?

Depending on where you are relative to your state plane zone, the discrepancy could be which kind of foot is selected?

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