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Sep 12, 2016, 09:52 AM
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Quote:
Originally Posted by Ianot
I live in the UK so do eurousc regulations apply here also when it comes to flying commercial. Where can I find more details on these regs, would it be from the CAA in the UK. Thanks
Directly from EuroUSC: www.eurousc.com.
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Sep 12, 2016, 05:43 PM
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Thread OP
It seems like I never answered this properly, you will see sub cm accuracy 2cm would be easily attainable.

It will work in Europe yes.

Steve

Quote:
Originally Posted by Ianot
Hi Steve,

What level of accuracy can be achieved with your system as I would need something less than 2cm. Does the system work in Europe? I'm looking for a system like yours that can be bolted on a leading commercial drone.

Thanks,

Ian
Sep 13, 2016, 01:56 AM
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Thread OP
Here is a small example on how to insert check shots.

You can't see it but we put a GCP at the four corners of the site and one at the high point on the only pile we were allowed to climb.

The two check shots are between GCP locations and there was no point to put a check shot at the top of the pile next to the GCP because data near a GCP is ALWAYS shown as accurate because the program will force the data close to the GCP into accuracy.

In Photoscan Pro check shots are not used to scale and reference the model.

BTW Photoscan has always been the most accurate but dang it's gotten even better over the past year.

This was done with Stryder and an X3 (not direct Geo)

We have an interesting site we did with Stryder along a highway and a real camera we will share next.
Sep 13, 2016, 05:01 PM
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I have been following this thread closely, and am excited for this new product.

Quote:
Originally Posted by saabguyspg
BTW Photoscan has always been the most accurate but dang it's gotten even better over the past year.
How have you come to this conclusion?
Sep 14, 2016, 02:28 AM
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Thread OP
We know this from running the same data sets through pix4d and Agisoft then compare results to check shots.

Agisoft has always been more accurate when comparing with our check shots.

However in the past year Agisoft has become incredibly accurate when using GCP's and our recent direct geo (no gcp) tests with Stryder are... well.... we have to re-run the numbers and do more tests because honestly we can't believe they are this accurate.... so I don't want to say

Now I do agree 100% that pix4d is much easier to use.

Thanks for stopping by and saing hello.

Actually I had such little response from this thread I was not sure anyone was following it



Quote:
Originally Posted by riley.chase
I have been following this thread closely, and am excited for this new product.



How have you come to this conclusion?
Sep 14, 2016, 05:47 AM
Registered User
Quote:
Originally Posted by saabguyspg
We know this from running the same data sets through pix4d and Agisoft then compare results to check shots.

Agisoft has always been more accurate when comparing with our check shots.

However in the past year Agisoft has become incredibly accurate when using GCP's and our recent direct geo (no gcp) tests with Stryder are... well.... we have to re-run the numbers and do more tests because honestly we can't believe they are this accurate.... so I don't want to say

Now I do agree 100% that pix4d is much easier to use.

Thanks for stopping by and saing hello.

Actually I had such little response from this thread I was not sure anyone was following it
Hi Steve
I say hello to. I am following it and we (my colleague and I) are waiting for the kickstarter because we want it badly and reading closely. We will raise question mainly as you will post more how to's etc because we are still learning and need a system for our M600's

Keep up the good works
Gerard
Last edited by Fotopiloot; Sep 15, 2016 at 02:33 AM.
Sep 14, 2016, 09:19 AM
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Thread OP
Hi Gerard, yes thank you for your emails too.

We found that we can pay about 500$ less USD per receiver if we used GPS only. However we found that in our tests GPS is not as good (obviously)

So we feel again it's best to spend a little more and get the reliability of GPS GLONASS.

I will let you know how hardware sourcing goes.

It's looking like $4750 USD for the complete set.

1 GPS GLONASS dual frequency L1 L2 base
1 GPS GLONASS dual frequency L1 L2 rover
1 Hard case
2 chargers
1 alignment plate for base
Software, support.

We are also looking at having wifi and bluetooth onboard in this rev for future software updates so that you can use your phone to start stop logging, name points, etc.


Steve
Sep 14, 2016, 10:57 AM
Registered User
Quote:
Originally Posted by saabguyspg
We know this from running the same data sets through pix4d and Agisoft then compare results to check shots.

Agisoft has always been more accurate when comparing with our check shots.

However in the past year Agisoft has become incredibly accurate when using GCP's and our recent direct geo (no gcp) tests with Stryder are... well.... we have to re-run the numbers and do more tests because honestly we can't believe they are this accurate.... so I don't want to say

Now I do agree 100% that pix4d is much easier to use.

Thanks for stopping by and saing hello.

Actually I had such little response from this thread I was not sure anyone was following it
I'm following! Fascinating.
Sep 14, 2016, 09:29 PM
Registered User
Squawk's Avatar
Quote:
Originally Posted by saabguyspg
Hi Gerard, yes thank you for your emails too.

We found that we can pay about 500$ less USD per receiver if we used GPS only. However we found that in our tests GPS is not as good (obviously)

So we feel again it's best to spend a little more and get the reliability of GPS GLONASS.

I will let you know how hardware sourcing goes.

It's looking like $4750 USD for the complete set.

1 GPS GLONASS dual frequency L1 L2 base
1 GPS GLONASS dual frequency L1 L2 rover
1 Hard case
2 chargers
1 alignment plate for base
Software, support.

We are also looking at having wifi and bluetooth onboard in this rev for future software updates so that you can use your phone to start stop logging, name points, etc.


Steve
Could you elaborate a bit about the 'alignment plate for base'?
Sep 14, 2016, 11:27 PM
Registered User
Thread OP
So when doing a proper survey you want to set up your base (ideally) over a known control point.

This point could be a nail in the ground or a properly placed monument (In Alberta they are called ASCM or Alberta survey control monument)

You want your base over this point as closely as possible... within <1cm if not mm accuracy.

We are developing and testing a few plates right now to allow for this without a tripod.

Of course you can always just screw it onto a tribrach (a fancy thing that allows you to set up over a known point with a tripod)

You can also set up the base somewhere else and "tie into" control using the monument.

It sounds complex but really it's not that bad.

You then enter the known co-ordinates of that control point (monument) into the software and then process the data to all the other points... done.

Not to worry all that black magic sounding stuff comes clear once you do it a few times and we are working on software that will make it simple.

Steve
Sep 14, 2016, 11:35 PM
Registered User
Fascinated too and also waiting for your Kickstarter!
Sep 15, 2016, 04:07 AM
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Squawk's Avatar
As you can tell, I'm a bit new to this. But a few clients are asking us for cm accuracy.
So thanks for explaining!

Just to be sure, with "known point" you mean that you look up a few "known points" from a "database" somewhere and see if they are within your area of operation so you can set up base on that?

What if such points don't exist here. Can't we just use a position (chosen by us and somewhere in the area of operation), place the base station there and wait for the base GPS to have a solid fix/lock?

Second thing, is a RTK GPS any different than a normal GPS? Or does RTK GPS just imply there is a link between 2 GPS's of which 1 is always stationary?
In other words, can any GPS in combination with another GPS and communication link between them, become a RTK GPS?
Sep 15, 2016, 03:41 PM
Registered User
Quote:
Originally Posted by saabguyspg
We know this from running the same data sets through pix4d and Agisoft then compare results to check shots.

Agisoft has always been more accurate when comparing with our check shots.

However in the past year Agisoft has become incredibly accurate when using GCP's and our recent direct geo (no gcp) tests with Stryder are... well.... we have to re-run the numbers and do more tests because honestly we can't believe they are this accurate.... so I don't want to say

Now I do agree 100% that pix4d is much easier to use.

Thanks for stopping by and saing hello.

Actually I had such little response from this thread I was not sure anyone was following it
Thanks for the reply! Yes we are following you .

If you don't mind, what method of checking are you using? Are you using the "checkpoint" method built in to agisoft or are you taking the surface and checking individual points in Civil3d or another software?
Sep 15, 2016, 10:03 PM
Registered User
Thread OP
No problem, many people are new to this even experienced surveyors.

Yes there is a way to find known points. Usually people refer to them as "control" you can get control from your client or the monuments put down usually by the government for surveyors to tie into. Now if there are no control points near by you will have to "Bring control to the site" this is something best left to an experienced surveyor or maybe a good explanation from my lead surveyor here would be better.

The big thing to remember is there a few levels of "accuracy"

Level 1
A survey NOT using any ground control markers. This type of survey is great for pretty photos but can't be used for any type of engineering work. It is not only inaccurate "locally" but also "globally" points, measurements will be off by inches, feet or more locally and globally out by many feet. You can not do a survey then overlay the same area the next day or next month and expect it to line up at all.

Level 2
Now you get your survey gear out and add some ground control points. Every 150m you put them and put a high and low GCP as well as a few extras in areas of importance. Now if you do not tie to control this will be accurate locally (with reference to itself) but will not tie to existing survey in the area. For example if another surveyor was there earlier your data will not line up with his and you will look bad.... to say the least. You can repeat this data set because you can set your base over the same point on the next survey but again it will not line up with other survey in the area.

Level 3
You lay ground control and you set either your base or one of your points that you designate as a "control point" as a known co-ordinate. This can be done by a permanent marker (ASCM or simlar) or a surveyor can "bring in control" from a known point and give you a place to set up over. He gives you the co-ordinates and so long as you set up perfectly over his nail etc. and input this into your base location you are off to the races. This gives you local accuracy as well as global for lack of a better term. Now your survey is repeatable and it will line up with the other survey data they have on site as well as surveys that are done after.

So now we can see just how important it can be to tie into existing control.

If you are flying without GCP (example Stryder Geo) then you don't need any GCP. However your base should be set up over a known point or control point. We don't believe in using network corrections for many reasons. The biggest is why pay subscriptions, second they are not in remote areas, you need cell coverage etc. The most reliable way is with your own base station. But to each their own.

To answer your question, you can just place the base station anywhere yes and get accurate local data. So long as your clients and you know it will be only locally accurate and will not line up with other surveyors data. This is OK too! really just make sure you are not meant to tie into someones control point.

RE RTK etc.
I will simplify. One GPS by itself is inaccurate to the order of meters no matter how long it sits.

However if you attain RAW data from a GPS that does not move you can use that data to correct another GPS and get cm level accuracy. So the one that does not move is called a BASE. This must stay stationary collecting data from the sats for the entire time of the survey. The one you move around is called a Rover.

Now you can do RTK or PPK. RTK is "Real time" as in you get see on a data collector that the position at the rover is being corrected and how good it is. This is quite handy, however you must maintain radio contact with the base at all times. Of course if you have seen a data collector and tried to use one.... they are far more complex than they need to be just to get one point.

PPK is "post process" this style has no contact to the base. With this style you place the rover down and wait a longer period of time than with RTK. With dual frequency RTK you wait about one minute maybe two. With PPK you would likely wait about 2 or 3 minutes.

With PPK you don't have to stay within radio contact and the longer your base sits the farther from your base you can be up to about 10km

When running PPK (OBS is PPK) you then put the sd card into the laptop and post process the data, out comes your cm accurate GCP locations and check shots.

However now we are almost certainly integrating Bluetooth such that there will be no more SD card slot in OBS and the data will be post processed on an android tablet instead of a laptop. More on that soon.

Hope that helps a bit.

Steve

Quote:
Originally Posted by Squawk
As you can tell, I'm a bit new to this. But a few clients are asking us for cm accuracy.
So thanks for explaining!

Just to be sure, with "known point" you mean that you look up a few "known points" from a "database" somewhere and see if they are within your area of operation so you can set up base on that?

What if such points don't exist here. Can't we just use a position (chosen by us and somewhere in the area of operation), place the base station there and wait for the base GPS to have a solid fix/lock?

Second thing, is a RTK GPS any different than a normal GPS? Or does RTK GPS just imply there is a link between 2 GPS's of which 1 is always stationary?
In other words, can any GPS in combination with another GPS and communication link between them, become a RTK GPS?
Sep 15, 2016, 10:04 PM
Registered User
Thread OP
Quote:
Originally Posted by riley.chase
Thanks for the reply! Yes we are following you .

If you don't mind, what method of checking are you using? Are you using the "checkpoint" method built in to agisoft or are you taking the surface and checking individual points in Civil3d or another software?
Hi there, we use the checkpoint method and we also check it in global mapper or Civil3D to be sure.

Steve


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