Geoid 12B

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
21

Hello,

There is a new article which could be of interest in this post: How to define Pix4D outputs with respect to a Geoid model

As for the International Feet or US survey foot, Pix4D can handle both. However, when you use a coordinate system which is defined in US survey foot, the units in the software still show Feet instead of US Survey Foot.

The coordinates system definition in Pix4D (as in many other software packages) is taken from  http://spatialreference.org/. By looking at the definition, the units can be easily known. For example:

PROJCS["NAD\_1983\_StatePlane\_Michigan\_South\_FIPS\_2113\_Feet",GEOGCS["GCS\_North\_American\_1983",DATUM["North\_American\_Datum\_1983",SPHEROID["GRS\_1980",6378137,298.257222101]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Lambert\_Conformal\_Conic\_2SP"],PARAMETER["False\_Easting",13123333.33333333],PARAMETER["False\_Northing",0],PARAMETER["Central\_Meridian",-84.36666666666666],PARAMETER["Standard\_Parallel \_1",42.1],PARAMETER["Standard\_Parallel\_2",43.66666666666666],PARAMETER["Latitude\_Of\_Origin",41.5],UNIT["Foot\_US",0.30480060960121924],AUTHORITY["EPSG","102690"]]

The system above is using Foot_US.

The following post can clarify: Orthomosaic not lining up with Google Earth

I hope this information helps you.

Regards.

22

Has Pix4D made any headway with other geoid models, such as the GEOID12B? I am using the trial software right now, but if there does not seem to be any motivation to allow for surveyors/geologists and others to produce work in NAVD88 then I think I will have to look to another vendor…

23

Hi James,

As I mentioned in the other community post, the vertical coordinate systems available in Pix4Dmapper are the three geoid models (egm84, egm96, egm2008) and the ellipsoid of the selected horizontal system.

If you need to select a different vertical datum such as the Geoid 12B, then you should either provide the offset between the desired geoid model and the ellipsoid of the selected horizontal coordinate system or to select the option Arbitrary for the vertical coordinate system of the outputs and the GCPs and import GCPs with coordinates in the coordinate system you specified.

At the moment, these are the possibilities. However, we are indeed aware of the importance of this functionality. Pix4D is constantly working on adding new tools that will improve the processing and analysis of 3D data. Please check out our official website for new products that might match your needs better: https://www.pix4d.com/

Best,
Teodora

24

This is actually a very simple problem to fix. Convert the coordinates of the UAS imagery to your survey grid coordinates (State Plane NAD83, NAVD88) before importing into Pix4D. If you’re collecting GCPs, then you should have survey software capable of easily translating between global and grid coordinates. I use Trimble Business Center.

In Pix4D you can export the image geolocation data to a text file, which will contain the global coordinates. Import that text file into your survey software to convert to grid coordinates. Then import the new grid geolocation data into Pix4D. Be sure to select Arbitrary for the vertical coordinate system, so Pix4D will not do any conversion.

This step literally takes 5 minutes, at most.

25

Thanks for elaborating on this, Andrew! Setting the VCS to Arbitrary after having converted it externally should solve this problem.

Best,
Teodora

26

Hello Everyone,

I do find Pix4Dmapper not accounting for local geoids relatively frustrating. With the high precision equipment that we have, producing very accurate horizontal information is easy even without any GCPs. It should be this way vertically as well. The frustrating thing is that this chain was started in 2015 (6 years ago at this point) and yet this has not been implemented into the product. However, it does seem that this task can be achieved in Pix4Dmatic. Unfortunately, I do not have that software, nor really want to use it due to its limitations in outputs (no .shp output abilities).
I do see Andrew M’s work-around above, but this is an extra step with a piece of software that I do not have.
Now that we do see Geoid 12b in one piece of software (Pix4Dmatic), will we soon see it or are there any plans to add it to Pix4DMapper?
Thanks,
AJ

27

I agree support for local geoids is very much needed in P4D Mapper. Pix4D Matic does not have all of the functionality as Mapper, so I can’t transition to Matic at this time. I haven’t seen any new features in Mapper in a long time. It’s very frustrating.

28

Thank you for sharing your feedback and apologies for the inconvenience. I passed your concern to our team for further development. If you have any other requests, I would appreciate it very much if you could post them at PIX4Dmapper Feature Request for the other users to vote for it. Our team will check the demands. Thanks!

Kind regards,

29

Andrew_Milanes

I’m trying to use your method to convert to our mine coordinate system. I can convert lat long easy through our software the alititude is in meters this is where I struggle not great at TBC I tried converting to feet then have it transform it but I seem to get funny data which makes pix4d freak out when running.

I was wondering how you handle that do you just use elevation of take off plus flight height based on site coordinates?

any help would be great appreciated I’ve been battling this dji rtk and pix4d stuff don’t want to use gcps every time.

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Create a new project in TBC. Set the desired projection and geoid. Then import the csv that contains image name, latitude, longitude, and ellipsoid height. In the import settings, make sure you have the fields set correctly. This article from Wingtra goes through the steps in TBC. It will be basically the same with your Phantom data.

Once the points are imported into TBC, they should be automatically displayed in the correct projection and elevation. Then export these new points to a csv. Point number, North, East, Elevation. Combine this data with the remainder of the geotag data (omega, phi, kappa, horizontal accuracy, vertical accuracy) from the original geotags file.

In Pix4DMapper, add the images and choose the coordinate system you used in TBC. Be sure to set the vertical to arbitrary, so no vertical transformation is performed. Import the new geotags csv file. Set the output coordinate system to the same as the input. Again choose arbitrary for vertical.

31

Thank you very much that helped get the data in for pictures, my question would be do I do anything with the base information there is a rinex file from each flight my guess is that is from the base.

or should I just convert pictures and run that method?

btw you are most help I’ve got or found on this topic in a month.

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also wouldn’t the coordinate system be arbritrary or would it be nad 83 state plane even though it might be rotated or offset

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I’ve never used an arbitrary horizontal coordinate system in Pix4DMapper. You might run into trouble with a rotated coordinate system, as your rotation parameters are referenced to true north. I would use state plane in Pix4DMapper, then use GIS to rotate, translate, and scale the output products, as necessary.

1 Like
34

Hi @eng_drone

Welcome to the Pix4D community.

Thank you for your question and thank you @Andrew_Milanes for helping reply.

You could also consider to use the site calibration:

It can be computed using a project with image geolocation in a known coordinate system (e.g. WGS84) and with GCPs in an arbitrary coordinate system.
Then, once the site calibration has been computed, it can be used in projects for which the image geolocation has been acquired using very precise GPS such as RTK GPS and in which no GCPs are used and the output coordinate system should be in an arbitrary coordinate system. For more information about how to use the site calibration parameters: How to use the Site Calibration Parameters.

I hope this helps.

Cheers

35

turned out its not rotated this process seems to be working have few glitches which will work on over time.

Thanks again you have been a huge help!!!

1 Like
36

Hi @eng_drone,

I’m happy to hear that you just have a few glitches to work on.

Happy processing!