Survey Coordinate entry. RTK GPS and even drone, help...

[tjones99]

Surveying is very time consuming. With RTK (Real Time Kinematics) GPS getting considerably cheaper it would be nice to be able to enter GPS coordinates for the data. A pair of RTK GPS units can literally be had for under $500 that can provide cm accuracy survey points. It literally should allow you to place a base GPS base unit at a fixed location and then place the rover GPS unit over each ball (element) and get a coordinate within a minute or two. It can be done in the dark when the site is not in use and the water is typically dead calm.

Any plans on allowing this form of data entry?

(for those not familiar with RTK GPS but are wary that GPS is not very accurate, the base unit and the rover get the SAME inaccurate coordinates and the base sends correction values to the rover so the rover knows within a few cm where it is relative to the base. The coordinates of the base are either known exactly before hand or they are determined over a period of time by averaging out a large number of inaccurate reading. The only important thing is to position the base exactly where it was for the previous surveys and to use the SAME base coordinate values every time for a re-survey to get the same results from the rover.

I have been experimenting with Reach RTK units but many more are becoming available such as Navspark RTK GPS, Drotek XL RTK GPS
Here+ RTK GPS. The latter two are suported by QGroundControl for use with drones which is the next step in making a waterski survey easier by taking photos from above using RTK GPS drone positioning and using Ground Control Points and multiple photos to get coordinates of every element on the water in literally a few minutes.

My biggest hurdle in all this is getting the coordinates into a form that Waterski Homologation Software can accept. I am open to anyone providing suggestions on any of the topics I have touched base on here...

[emmanuel]

Hi,

In the Homologation software, there is already a possibility to enter x/y coordinates.
Some theodolites provide such output.

Otherwise, I could implement the GPS coordinate input...
But I am missing some technical information.
Could you provide a GPS coordinates list, which correspond to a waterski survey (slalom course...) ?

Is there an interface on RTK GPS Equipment to communicate their measurements to the software (COM, Rs232 over BlueTooth) ?
if yes, could you provide the documentation to see if I can implement it ?

Emmanuel

[tjones99]

Thanks Emmanuel for the prompt reply and the willingness to look at this option.

I will do a full GPS survey of our slalom course and provide the GPS coordinates. I believe there are ways to convert the GPS to XY coordinates and then enter them in using that approach but every additional step (i.e. conversion) adds complexity.

I do not think there is a way to obtain the point by point data via RS232/COM port/bluetooth, what I have seen so far is the survey programs output the equivalent of a CSV file of GPS coordinates. The Reach RTK solution I am experimenting with lets you name each survey point so the plan was as I survey I would name them G1 G2 B1 B2 S1 S2 etc as I captured the data then if there was a direct way to enter GPS coordinates it would be a copy/paste operation... I am not sure what the survey data for the other units looks like but I suspect it will be similar.

Still ice on the ski lake here so the balls are not quite in the water yet to do a real survey but I think next weekend might be possible...

[emmanuel]

Hi,

With x/y coordinates, I meant that some of the theodolite provides themselves x/y coordinates.
Then there might be something similar in RTK GPS systems.

Well if not, as said, I could add that, but I need help for GPS data and software test, as I am not homologating anything anymore, and do not have such GPS system myself.

If you are willing to help, it should be possible for me to add that feature in software.

Doing the full slalom survey will help (even a frozen slalom survey !), thanks.
If you can export a CSV file with named points, please attached one here: I could add an import function to the software.
If the points are named exactly as in the software, this would automate the whole thing.

Emmanuel

[tjones99]

I am 100% on board with working with you on this!

I will get you a full slalom course survey to start with. Will name each point exactly as they are in the homologation software to simplify and eliminate confusion. The survey I will provide will be from a real course that we just put in through the ice this winter... the ice is finally out now actually so I will clip on the balls and do the survey. I hope to get that done this weekend! It should be close to RC right off the bat (the one advantage of being able to walk on the lake to in install a slalom course... well actually, we drove on the lake which makes it a lot easier moving tons of anchors around). Amazing what you can do with a chainsaw and a measuring tape!

Look forward to working with you on this!!

[emmanuel]

What would be very good to get from you as well, is the same slalom surveyed with both GPS and normal theodolite.
(without changing any buoy position in between, of course).
Then, once it is programmed, I could compare the issued results to be sure the software is working.

Having only GPS survey, could issue a slalom course that show like a slalom course, but over scaled or under scaled, if earth ellipsoid and altitude is not correctly integrated in GPS coordinate transformation.

Emmanuel

[tjones99]

That will take longer to get but that can and will be done. Won't happen this weekend as the total station is off at another site doing a survey... Completely understand where you are coming from on this request.

[emmanuel]

Don't worry if not this week-end:
I need more times to find out how to work with GPS coordinates,
and then to program in software...
But I will start, and then when I get your survey, finish the work.

Emmanuel

[emmanuel]

Hi Terry,

Did you have the time for a GPS survey ?

Emmanuel

[tjones99]

Have done the traditional total station survey but have not done the GPS survey yet. Hopefully will have time this week.

[tjones99]

Here is the RTK GPS survey data for the slalom course. Will follow up with the survey data from total station when I get that file.

I have named all the elements as per your software. Should be easy to correlate.

This is in LLH format.

See what you think...

I am looking at LLH to ECEF conversion tools to see if they will do what we need.

[tjones99]

here is the traditional survey...

[tjones99]

I have to say this looks promising as a survey approach. I have spent countless hours with a partner where one is on the total station and the other moves the prism around the lake.

This approach can be done by a single person. The base is placed in a fixed location. The rover is moved from ball to ball. I used an iPad to capture each point and named for the water ski homologation program as I went along. I think it took me an hour and a bit total to survey a slalom course. It doesn't have to be an iPad. For the Reach units I was using all that is needed is ANY device that has wifi and a browser. That is the total technical requirement. The Reach RTK GPS provides a wifi hotspot. You connect to that wifi from whatever device you are using (so the device has to be within wifi range so you usually have to follow the GPS unit around the lake as the wifi will not reach shore from one end of the course to the other... maybe if you walked along shore parallel to the course it might but then you are back to two people, one moving the GPS and one recording...)

I was doing this early in the morning when it was calm, but it was extremely hard to see the iPad in the sunlight... which turns into another advantage I believe... The best time to do this survey is at night. At night it is calm usually. At night the lake is not being used for skiing. At night the iPad is easy to see. Especially leading up to a level of tournament where you need to survey... lake time is a premium so being able to do this survey in the dusk or even total dark is ideal.

I just added some pictures to show the gear. The gear is complex but the whole setup is pretty simple and using it is pretty simple compared to a total station in my opinion. My setup is as follows:

2 Reach RTK GPS units with GPS antennas
2 SIK (3DR) radio units
2 batteries
One smart device (iPad, iPhone, Android tablet or phone, laptop, tablet, whatever)

[emmanuel]

Hi Terry,

Thanks for your GPS test file and the traditional survey.
I will work on that on soon as possible.
As I am quite busy, it might be a few weeks until I get something programmed... and working !

I give you some news as soon as it get further.

Emmanuel

[tjones99]

Thanks Emmanuel.

I am also looking into command line utilities that may work to convert the GOS data to XYZ data. I will keep you informed on my progress.

Any thoughts on this survey approach in general?