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Google Earth orthomosaic tiles and USFT

Hello,

I recently noticed that google tile output seem to have an international foot to US Survey foot shift issue. Seems like the output converts tiles to international foot, which is causing approximately 12-15ft shift when viewing in Google Earth.

My project was set to NSRS 2007 CA state plane zone 6 (usft). However, when looking at tiles in Google Earth, it looks like it was converted with International Foot?

Thanks,

Mike

Hello Michael,

There is a community post where a user described exactly the same issue that is happening to you.

You can see it here.

What is the output coordinate system you have selected in Pix4D exactly? Is this one?

If that is the case, the defintion is:

 

 

That means that for the Google Earth export, the conversion is using US foot.

Would you share the Quality Report? If you are using GCPs, are they given in feet or US survey foot?

Regards.

 

 

 

 

Hello Daniel,

Yes my survey and Pix4D project are based on NSRS (2007) California, Zone 6, US survey feet. However, let’s be clear… the primary Pix4D outputs (.las, Dsm, ortho) are in usft and match the GCPs and check points, which were also in usft. The problem is the output tiles for google earth only. These tiles seem to have a shift that I suspect is incorrectly converting from USFT to the web based auxiliary Mercator projection used in google earth. I see this issue for for other projects set up with usft in Pix4D as well. Again primary outputs are correct…it is the google tiles that have a shift.

I will upload a screen shot of the quality as soon as I get to my office.

Thanks,

Mike

Hello Michael,

We would need the images and project to replicate the problem here.

Would you share it with us?

Thank you very much.

Hi Daniel,

 

Please click the link below for the pertinent data discussed above.

https://1drv.ms/u/s!AshJwvSEGv7qj4YZ2FVsP0LdSQnsAg?e=xjzOGw

Please note that KlauPPK was used to generate a Coordinate Image file.csv, so please use that for image location.  This file alon wit the GCP/Check Point.csv file are all based on NSRS(2007), California, Zone 6 USFT. 

I also included the exported google earth tiles, so you can see what I was referencing.  I did checks on the “Primary” Pix4D output files in ESRI ArcGIS v10.6 and Civil 3D 2019 and all were correct with no units conversion shift.

I should also say I recently did another UAS mission at the same site on 6/28/19 and got the same shift in Google Earth tiles.  However for that site I used a Sony RX1RII so the images are really big…hopefully, you can recreate the issue with the 1st mission.  If not I will share the 2nd mission, if needed.

Thanks for your help.   

 

Mike

Hi Daniel,

 

Just circling back regarding this.  Were you able to see the “shift” on your end?

 

Thanks!

Hi Michael,

we were not able to reproduce the issue on our side. We cannot see any shift when opening the .kml on Google Earth Pro. There are some distortions on the edges, but this could be due to the lack of overlap. Where exactly can you see the shift?

Alice