Survey Control Methods

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charlesdab
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Survey Control Methods

Post by charlesdab »

Hello All-

I currently use an S70 and Scene and am interested in adding some survey control with a total station. I am looking for some guidance on best practices for adding survey control to my workflow.

When adding survey control, what are you normal shooting? Reflector-less to a checkerboard? Reflector-less to a sphere? Adding a PK nail and setting CP then adding a target on top?

Does anyone have any video or manual resources that may be able to help?

Thanks!
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Re: Survey Control Methods

Post by Dave Andrews »

I use Faro, this is how I go about survey control.

I do shoot checker target reflectorless. I use them for column centerlines and elevation, not for primary control.

I also use spheres over PK nails on a tribrach.

Mostly for spheres, I use a -30 seco prism with a Kopo Sphere on top. The tribrach is fairly expensive and I believe the most accurate on the market. Once it is level you can shoot the prism with a negative rod height to the center of the sphere. Nice easy export to excel and straight into Scene with no extra work.
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Re: Survey Control Methods

Post by landmeterbeuckx »

Use this setup : spheres replaced by a prism which shows the center of the sphere. Adapter in tribach.

This is more secure then setup above where errors are easily made with calcs.

https://shop.laserscanning-europe.com/M ... Sphere-Set

https://shop.laserscanning-europe.com/T ... n-sphere_1

But to remind you : running a total station around a building isn't as straightforward as pushung buttons on a scanner. There is a special breed for those to operate which are called "A Surveyor". Get in contact with one and see what would be best in your workflows.
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Re: Survey Control Methods

Post by tengui »

charlesdab wrote: Wed Jan 26, 2022 11:06 pm Reflector-less to a checkerboard? Reflector-less to a sphere? Adding a PK nail and setting CP then adding a target on top?
A mix of all of those, depending of what's possible or most convenient.

Lately I've been using these: https://shop.laserscanning-europe.com/3 ... -100-piece more and more, in combination with this prism: https://shop.laserscanning-europe.com/M ... Sphere-Set.

Occasionally, these: https://shop.laserscanning-europe.com/S ... ut-support. Bubble them over a nail with a simple rod level. They're a bit cumbersome, but not as much as a full tripod+tribrach, especially when you need several of them at the same time for a single scan.

(Might I add that I'm not affiliated to laserscanning-europe :D . There are other shops as well.)
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Re: Survey Control Methods

Post by landmeterbeuckx »

tengui wrote: Thu Jan 27, 2022 10:39 am
charlesdab wrote: Wed Jan 26, 2022 11:06 pm Reflector-less to a checkerboard? Reflector-less to a sphere? Adding a PK nail and setting CP then adding a target on top?
Occasionally, these: https://shop.laserscanning-europe.com/S ... ut-support. Bubble them over a nail with a simple rod level. They're a bit cumbersome, but not as much as a full tripod+tribrach, especially when you need several of them at the same time for a single scan.
Those are only good to place your spheres above ground. They can be placed everywhere but don't ever use them for control. After a few times usage they get wobbly and the disc comes loose.
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Re: Survey Control Methods

Post by charlesdab »

These are all great tips. Thank you.

Luckily my use case is not so tight that I feel like I need to engage a surveyor. Since I have direct line of sight to all points from one total station location, I think I should be OK.

All I want to do is reference my scans to the local coordinate system. It seems like total station with survey control may be my best bet on these projects. Without that I'd be aligning it manually.
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Re: Survey Control Methods

Post by LPaulCook »

I use checkard targets and duct tape them over one of my control points I shot in using my total station or taped to a flat surface and shot in with my total station using the reflectorless setting. I try to get all shot in from the same station but that's not always possible. This method is plenty accurate for all my work in building scanning and Topographical surveys. I am a land surveyor so I have the equipment anyway.
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Re: Survey Control Methods

Post by mikajahkola »

When you measure checkerboard targets with a total station, your targets will generally not be perpendicular to the line of sight, but at varying angles.
The laser spot of the total station has some finite size and if it hits the target at a large angle of incidence, the spot could grow quite large and have an irregular shape.
A black and white checkerboard target returns a much stronger signal from the white part than the black part. This is not a problem as long as the target is looking straight at you, but if it is angled, the distance measurement may go wrong because the white part tends to dominate the result.

In your experience, at what angles of incidence can you still measure checkerboard targets reliably, and how do you mitigate any errors that arise?
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Re: Survey Control Methods

Post by LPaulCook »

I use a Leica TS16 robotic 1" instrument. They have a very small laser dot, unlike some others. Nevertheless I agree that the target should be very close to perpendicular to the line of sight.
If that can not be achieved the run a traverse to another position that is in the correct relationship to the target. Then close your traverse to be sure that traverse is correct and within your allowable accuracy tolerance.
Shooting topography can be much looser than Shooting a factory so set your accuracy standards accordingly.
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Re: Survey Control Methods

Post by jcoco3 »

Considering the concerns expressed over the size of a total station's beam size, this seems like something relevant to add to the conversation:
viewtopic.php?p=84584#p84584
I second the concern about reflector-less shots, which is not to say they cannot be accurate with the right knowledge and practice.
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