Support Website Contact Support Blog

Coordinate System of GCPs - GDA2020 (new datum for Australia)

Hi Pix4D Technical team,

We flied Phantom 4 RTK and obtained RGB images whose coordinate system is recognized by Pix4D as WGS84 / UTM Zone 56S (we are in NSW of Australia); The coordinate system of GCPs collected by our surveyor is MGA2020 (I think it is GDA2020, the new datum for Australia), zone 56s, Height is on AHD71.

Just wondering if I can import the GCPs with that specific coordinate system, and ensure they are compatible with the coordinate system of images at Pix4D for processing.

If not, how can I do to make them compatible?

Your help is much appreciated.

Cindy

Hi @cindy.wang,

First of all, you have to download the latest Pix4Dmapper preview 4.6.1 where GDA2020 is included and create a project from scratch. Afterwards, in my opinion, you should do the following:

  1. Add images and ensure WGS84 / UTM Zone 56S = EPSG:32756 is detected.
  2. In Select Output Coordinate System window, select Advanced Coordinate Options and look for EPSG:7856 in Known Coordinate System. In the Vertical Coordinate System select Arbitrary.
    Explanation: At the moment, Pix4Dmapper doesn’t support any geoid except for the global geoids EGM 84, EGM 96 and EGM 2008. That’s why AHD71 is not available. As a workaround, you should set your vertical output coordinate system to arbitrary and your vertical GCP coordinate system to arbitrary, but leave your collected GCP coordinates untouched. This will fit and export the vertical model according to your GCPs.

Let me know if it works.

Thanks! :slight_smile:

Hi Thank you for the reminder of updating the most recent version of Pix4D. Will contact Sales Pix4D about the payment.

Not sure how long the purchasing process will take, but I need to process the data and get the result ASAP. Therefore, I am transforming the GCPs from GDA2020 to GDA1994 which is included in Pix4D 4.4.12.

For vertical coordinate system set up, can I just follow your suggestions, and try the same steps???
Any suggestions, please feel free to let me know.

I am getting the GCPs with GDA1994 late this afternoon, and will try processing data after, and let you know how it goes.

Thanks !!

Hi @cindy.wang,

My apologies for the late reply. Yes, please follow the same steps and let me know how it goes.
In case something happens I’m here to support you :slight_smile:

Regards!