Converting Geoids to Geodetic TIFF grids (GTG) format

[Hof]

Hi, I have two geoids created in SAGAGIS: PL-EVRF2007-NH-9702 and PL-KRON86-NH-9702. I can't upload them into Agisoft Metashape version 1.8.1. Can anyone help me with conversion of this geoids into format acceptable by Agisoft please? What kind of software should I use to create correct GTG files?

https://drive.google.com/file/d/1JZrD7iFrQA6u6sh_ZRv8gUVxwMpFsjqR/view?usp=sharing
https://drive.google.com/file/d/1uCBl3qwu45EE6BY8IY8a_yW-m4TxO3l9/view?usp=sharing

[Paulo]

Hello Hof,

you can look at https://www.agisoft.com/forum/index.php?topic=12602.msg58174#msg58174 for link to download correct PL-EVRF2007-NH geoid and also KRON86-NH in first page. I think your files do not have a datum reference (ETRS89) so that it is why it cannot be loaded...

[Hof]

Hi, Thanks for the reply. Geoids from that post worked fine for Agisoft below version 1.7. Now I need geoids with a datum reference (geographic CS) EPSG:9702. This part is not a problem and I did the transformation. What is the problem, is that geoids have to be in Geoids to Geodetic TIFF grids (GTG) format. Geoids from the post you mentioned are not in that format and Agisoft from version 1.7 doesn’t recognize them. Does anyone know a software that can convert GeoTiff file into Geodetic TIFF grids (GTG) format? Preferably open source.

[Paulo]

Hello Hof,

on my side it workd. I created a compound CS with PL EVRF2007 NH Height and placed 2 markers on the map and extracted their geoid height. Comparing to values exracted from geoid tif file on GM, the values are the same..i.e. legacy format geoids as this one still work with versiona 1.7-1.8 as well as GTG format

[Paulo]

Hello Hof,

I was able to download your EVRF2007 tif and import it into Metashape referrenced to your ETRF2000-PL datum  as follows;

1. In Select Coordinate Sytem Window, find ETRF2000-PL GCS and use edit button;
2. In Edit Coordinate Sytem Window, select Custom in Vertical CS;
3. In Edit Vertical Coordinate Sytem Window, enter EVRF 2007 NH Height in Name and select Add... in Datum;
4. Navigate to your PL-EVRF2007-NH-9702.tif file and select it;
5.  In Import Geoid Window, enter EVRF2007-PL height in Vertical CS and OK;
6. In Edit Vertical Coordinate Sytem Window, click OK;
7. In Edit Coordinate Sytem Window, enter ETRF2000-PL_EVRF2007 NH Height in Name and OK.

You now have a compound CRS with your file as geoid height...
see following attachements....

[Hof]

Hi Paul,

It seems to be working fine. Thanks lot. Although it’s strange that i have to choose EVRF2007-PL hight (EPSG::9651) as Vertical CS in point 5 of your instruction. I don’t understand why. It didn’t work like that in previous versions. I think that when I added PL-EVRF2007-NH.tiff geoid it used to assign the name of the file (PL-EVRF2007) automatically. Never mind, what matters is that it works correctly.

Regards,
Hof