3d Terrain mapping 3D Model

Hello,

I want to use two tiny rtk u-blox NEO-M8P-2 (one for base, one as rover) to generate a 3D model of a terrain (100x100m) with elevations (as point cloud) by simply walking over this area with antenna of rover at defined level over ground while recording the (x,y,z) coordinates to a file.

Is this possible with a precision of 2-5cm in z-direction (=height)?

If yes, what other components do I need (base-rover transmitter, antennas, software) and how to configure the base, rover and U-center software?

Thanks!

The precision in Z direction is the double of X and Y.
You need to order one rover RTK GPS, one base RTK GPS and a radio telemetry.
You can find more information on DOCS and LEARN section of the site.
Don’t hesitate if you have further questions.

Hi Stepo

Tou have to be aware that:

1- tiny RTK gives 2.5-10cm relative precision. And no absolute precision.
2- to have an absolute precision you have to correct it using terrestrial stations. (RTKLiB f.e.)
3- tiny RTK does NOT produce RINEX or NME data straight forward.
4- you have to consider a good antenna and a ground plate for patch antennas in order to increase signal reliability.
5- as tiny RTK only is L1 band it is more likely to be affected by rebound interference and trees.

I have asked many times here and to ublox on how to get RAW Data on RiNEX format and so far I have never had an answer.

It seems possible but not straight forward. Nobody tells me how. Unfortunately I could not find it by myself neither

However I am not unhappy with tiny RTK solution. Knowing limitations of the product is very important. I am using it for drones and in terms of trajectory reliability it gives very good results.

So I am wating to know how to correct all those GPS points for absolute precision (via RiNEX/RTKLiB or whatever ).

Dan

Hello
I have exactly the same purpose. Is there a tutorial which explains how to use PPK with tiny RTK?

I would be very interesting. Anyway I am not sure about the first point. Tiny RTK gives 10cm precision but if it is in fix mode it is an absolute precision . PPK is a processing just to improve the “fix mode” ? Am I wrong on that?

Hello Dan,

thank you for the informations!

Is there maybe another device that supports RAW data output and aboslute precision like the SMARTNAV L1 RTK GNSS?

Hello, a few additions to your comments :

  • it is possible to use TinyRTK with an absolute precision, that only depends on the positioning precision of your base. If you use Survey-In mode, you will likely introduce an offset, but if you use Fixed mode then you are working in absolute mode.
  • TinyRTK can output raw messages that can be directly converted to RINEX with RTKlib for example

Hi Kevin

Thank you for your answer.

The big question therefore is : would it be possible to show us how to get the raw messages from the output please ?

As far as I know, exporting messages does not give raw messages, so it cannot be converted to RINEX.

Thanks

Sorry, I just figured out that someone else answer it to me in other post (any other option?)

Hi Dan,

1st, you have to set the UBX messages to be outputted. This can be done using u-center > Configuration > Messages > RAWX, ???X , ???X to be turned on at UART and USB.

2nd: you need a kind of logger (an external for UART or a PC for USB). For PC, start u-center, an press the record button. This will create an *.ubx file from the datastream derived from TinyRTK. If you need a UART GNSS Logger, contact me. Our company REDcatch is producing one and will shortly ship them.

3rd: You need step 2 at both, Rover and Base. So two *.ubx files at the same time period + 12minutes

4th: Use RTKconv.exe from RTKlib to convert *.ubx to rinex *.obs

5th: Use RTKpost.exe from RTKlib to postprocess the Rover positions with the one from the Base. (Use Kinematic mode, and “Fix and Hold” on both, GPS and GLONASS.)

6th: Eventually you have Trigger events, from UAV? You also have to geotag the images… For this, we will provide a software with the logger mentioned above.

Everything a bit tricky, but working very well. Keep us up to date, if you are able to manage the steps in this short guide.

best regards,
Hans