RTKLib Geodetic vs ellipsoidal Datum Question

[mwfoshee (Mike Foshee)]

I wish to add geotags to my images, my current workflow:

1. Download logs from reach
2. Postprocess against CORS data to obtain fix and camera event.pos file
3. Convert event.pos file to .gpx using the KLM/GPX button on the main RTKPOST screen
4. use the .gpx file and geosetter to add tags to my images

The elevations in the event.pos file appear correct using these settings, however, when I then use the KML/GPX converter (from the button on the main RTKPost screen) I have to pick again Ellipsoidal or Geodetic. If I choose off, no elevation is calculated in the gpx file.

It seems to me, the only way to achieve correct elevation data is to pick each model once. If I choose ellipsoidal in the main options then I must pick geodetic in the GPX convert menu.

Question 1- is this coincidence is is this the correct workflow?

Question 2- To be most accurate, does it matter which one I pick in which screen or does it work as long as they are opposite?

Question 3- In the options, on the output tab, I choose WGS84 (no other option), Geodetic and internal (I choose internal as I don’t recognize the other available geoids) What internal geoid model being used?

[andrew.yushkevich]

Hi @mwfoshee

@mwfoshee

Question 1- is this coincidence is is this the correct workflow?

@mwfoshee

Question 2- To be most accurate, does it matter which one I pick in which screen or does it work as long as they are opposite?

As KML/GPX converter work as a separate tool, you need to set all settings during each step.
So, it’ a correct workflow.

@mwfoshee

Question 3- In the options, on the output tab, I choose WGS84 (no other option), Geodetic and internal (I choose internal as I don’t recognize the other available geoids) What internal geoid model being used?

In that case, RTKLIB will use interpolation model with 1deg grid spacing based on EGM96 geoid model.