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Author Topic: P4RTK and Evo2 RTK - Dealing with mrk files.  (Read 2285 times)

dpitman

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P4RTK and Evo2 RTK - Dealing with mrk files.
« on: January 07, 2022, 01:48:27 AM »
On these drones, precise camera positions are written to a text file (.mrk) 
Unfortunately, the coordinates are not written cleanly with a header, but rather with text added to each value.
For example, an image will have the coordinate values "36.0138568743,Lat   -115.2255755428,Lon   794.088,Ellh".

How are others converting this to a .csv to import as a camera reference file into MS?  It is easy enough to delete or exclude columns in the .mrk file that are not needed.  But how to remove the text at the end of each coordinate value, e.g. ".Lat" without doing it one by one.   Perhaps it can be done with a python script?
Sample file attached.

Thank you!
Dave
« Last Edit: January 07, 2022, 01:57:23 AM by dpitman »

hadestong

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #1 on: January 07, 2022, 08:40:16 AM »
Actually the .mrk file doesn't contain precious position,YET.
As you can see from the file name "timestampe", it means recording the GPS time and original GNSS coordinates when shooting pictures, and if you got a GNSS base station near your flight location, you can process the MRK file with the base station AND EVO2 RTK RINEX file to get a real precise position file by using some kind of PPK software such as GeoTagZ from septentrio.
« Last Edit: January 07, 2022, 08:42:29 AM by hadestong »

gto234

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #2 on: January 08, 2022, 01:00:20 PM »
On these drones, precise camera positions are written to a text file (.mrk) 
Unfortunately, the coordinates are not written cleanly with a header, but rather with text added to each value.
For example, an image will have the coordinate values "36.0138568743,Lat   -115.2255755428,Lon   794.088,Ellh".

How are others converting this to a .csv to import as a camera reference file into MS?  It is easy enough to delete or exclude columns in the .mrk file that are not needed.  But how to remove the text at the end of each coordinate value, e.g. ".Lat" without doing it one by one.   Perhaps it can be done with a python script?
Sample file attached.

Thank you!
Dave
You can use notepad++ or other notepad app to replace (Ctrl+H) the ,Lat with no character. You do the same with the other ,Lon ,Ellh
It is a very easy if I understand correctly.
See the attachment if this is what you need.

dpitman

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #3 on: January 08, 2022, 07:47:45 PM »

You can use notepad++ or other notepad app to replace (Ctrl+H) the ,Lat with no character. You do the same with the other ,Lon ,Ellh
It is a very easy if I understand correctly.
See the attachment if this is what you need.

Excellent tip, thank you!

Dave

c4moto

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #4 on: February 04, 2022, 07:04:22 PM »
Dave,
I am an Evo II Enterprise/ RTK user and I am curious about what this process involving a camera reference .csv is used for.
I have added photos to my projects and noticed high accuracies in the reference panel.
Is there an added benefit with the .mrk file?
Curt

Paulo

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #5 on: February 04, 2022, 08:19:26 PM »
Hello c4moto,

if the RTK has been successfully accomplished during the flight with RTK corrections being sent from the base to the rover, then the camera coordinates will be precise and this will be reflected in each camera Exif data. This is seen by looking at GPSXYAcuuracy and GPSZAccuracy entries in Exif data. And this accuracy will be read by Agisoft during image import. For example here is an extract from Exif of an Evo2RTK image:
Quote
---- XMP-Camera ----
Pitch                           : 0.070000
Yaw                             : 88.870000
Roll                            : 0.000000
GPSXYAccuracy                   : 1.093456
GPSZAccuracy                    : 2.998834

AboveGroundAltitude             : 761.994629
ModelType                       : perspective
PrincipalPoint                  : 6.585612,4.437313
PerspectiveFocalLength          : 10.131384
PerspectiveDistortion           : 0.072300000000,-0.230500000000,0.272600000000,0.001000000000,0.001100000000
HorizCS                         : EPSG:4326
VertCS                          : ellipsoidal
as you can see in this case the accuracy  is at the meter level and thus posprocessing (PPK) of base, rover GNSS data along with Time stamps file (MRK) would need to be done to get cm accuracy.

Hope this helps,
« Last Edit: February 05, 2022, 09:00:47 PM by Paulo »
Best Regards,
Paul Pelletier,
Surveyor

c4moto

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #6 on: February 04, 2022, 10:24:45 PM »
Got it.
Thank you, Paul.

dpitman

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Re: P4RTK and Evo2 RTK - Dealing with mrk files.
« Reply #7 on: February 05, 2022, 08:43:24 AM »
Hi Curt,

Paulo answered nicely.  The .mrk file comes into play when the workflow is PPK vs RTK.   This can be helpful if either RTK is not available or, for some reason, the RTK connection fails.  Centimeter accuracy can still be achieved with the PPK workflow. 

Dave