Hi Everyone.
Is it possible to apply custom geoid to Pix4D? I have Phantom IV RTK and I want to apply OSGM15 geoid (UK+Ireland), as I’m having systematic vertical difference (vs handheld GPS RTK coordinates) when applying predefined geoid EGM2008 (before appying GCP). I think with RTK accuracy I shouldn’t have that problem with proper geoid applied.
Have TIF file with OSGM15 definition, but doesn’t work, when put to folder with other geoids.
Many thanks.
Przemek
Hi,
Yes, it is possible to use a custom geoid, but there are a few rules to take into consideration:
Pix4D does not support the use of local geoid models yet, so the conversion to the desired local geoid has to be performed before importing the dataset into Pix4Dmapper. Transforming the vertical coordinate system of the RTK dataset (and GCPs, if it is the case) is applied by using an external tool provided, for example, by the national mapping institute.
A constant height and a global geoid could also be used although the accuracy will be lower. If you use the constant height, you will likely obtain inaccuracies, because it is not 100% certain that the elevation of the dataset has a constant offset compared with the geoid of reference.
For more information about vertical systems in Pix4Dmapper, please read the article
Cheers,
Teodora
Teodora,
Thank you, I tried all above before, just wanted to know, if there is a shortcut by applying custom geoid. Helpful when flying over difficult areas, where no GCPs can be installed.
Found a way around it anyway, just takes little bit more time.
Reg.
Przemek
Hi,
Unfortunately, there is no shortcut at the moment. Currently, Pix4Dmapper lets you choose from the geoids EGM 84, EGM 96 and EGM 2008. Converting to other geoids has to be performed beforehand, with 3rd party tools.
It is nice to hear you found a workaround. However, Pix4D is constantly improving and adding new functionalities, in order to optimize the processing and analysis of 3D data.
Cheers,
Teodora
Will it be possible to upload a user geoid file to Pix4D Mapper? Or can Pix4D look to load more geoids into the next version? We are currently using NZVD16 which I now see is supported by Pix4Dmatic, so it appears that this can be done?
Hi @rpas2,
Indeed, in Pix4Dmatic, it is possible. However, in Pix4Dmapper it won’t be. Instead, you could select the option Arbitrary Coordinate System for the outputs and the GCPs and import GCPs with coordinates in the coordinate system you specified. In this case, the software will respect the GCPs values and will try to fit the model as good as possible to the GCPs. Then, all your outputs will still be in an arbitrary reference system, but this system will be based on the system defined by the GCPs.
Regards
Hi Beata!
This is somewhat the explanation I was looking for. To make sure I understand: I have images with a seperate .txt image orientation file (with CRS = ETRS89 UTM zone 32N + NN2000), as well as a GCP file with the same coordinate system. What I should do is to import the images, the orientation file, and the GCP file using the arbitrary coordinate system option for all of them. I should also use the arbitrary coordinate system option for the output. This would allow me to process my data and the export would be in the same CRS as the GCP and orientation files. Is this correct? Is it enough to set only the vertical CRS to arbitrary since Pix4D does accept the 2D CRS ETRS89 UTM zone 32N?
Thank you very much in advance!
Hi bjorn,
Yes, if you have GCPs then just set your vertical to arbitrary. Your outputs will reflect the elevations of your GCPs. But, you will definitely want to set the correct horizontal coordinate system. In your case use ETRS89 UTM zone 32N.