using M300RTK and Pix4d Mapper

[Philos]

Hello, I'm new to the forum, I just bought an M300RTK ,P1 Camera with Pix4dMapper as processing software.
I edited my flight plan with dji pilot, the D-RTK2 was setup and I even flew over a zone.
someone can help me with a data processing procedure that show how to process drone data.
I have only pix4dMapper as processing software.

 

[jaja6009]

There are a lot of questions that would need to be answered to fully help you.

But, I will assume some things.
I assume you are not in the US, so you datum and coordinate system could be WGS84 with ellipsoid , but I don't know.

If you flew RTK and had FIX it is pretty easy.
Open Pix4D
Name Project
Import Images, make sure you choose the correct datum for the images on this screen. For me it is NAD83(2011) Geographic, and use the Height Above ellipsoid for vertical system with the field being 0 (This means that the elevations are ellipsoid values) For you the datum will be whatever your DRTK was using (Setup on a point or receiving corrections from an RTN RTK NTRIP service).
Import your control points, choose the datum and coordinate system that they are in along with vertical and then use the Basic Editor to mark them in 5 to 10 images. Assign them as either a Check or GCP.
Choose Maps and Models for output
When you get to the project screen, you can still go in and change the output datum and coordinate system if they differ from your control points. You want to output in a projected system (Most Likely, but I am not sure about your goals).
Run Step 1 only to create sparse cloud.
After sparse cloud is completed, use the GCP editor to fully mark all control points and assign the control points as either GCP or Check Point.
Reoptimize
Ensure that everything looks good.
Run steps 2 and 3.

Your biggest problem will be the datum and coordinate system you used with the DRTK. If you are receiving RTN RTK corrections the service can tell you what datum they output in as well as vertical datum and that will be your imported images datums.
If you setup your DRTK over a known point, then whatever datum the point is, that is what datum your drone images are in.
If you just setup the DRTK by itself where it is not over a known point or receivng RTN RTK corrections it is in WGS84 ellipsoid and not very accurate even with averaging that point.

 

[Philos]

Hi Jaja,

Thanks for the guidance,
I'm in Africa (RDCongo), we are using UTM coordinate system and WGS84 datum.
the DRTK was setup on a know point and no GCP were marked in the field.

When I compare my file and the old survey made with the DGPS, I notice a shift of 1.2 m in northing, 0.8 easting and 0.4 m in elevation.

I would like to understand at what step I need to georeference the images because my DRTK was set to the known point and no GCP was marked.

 

[jaja6009]

Are you sure you were using RTK with your M300 RTK, as in did you go into the settings, turn on RTK, get a connection to DJI DRTK and have FIX for all of your images?

Next are you sure that your DRTK was setup on the point AND you were not averaging in SINGLE? Meaning you are sure you chose the option to enter the manual coordinates (In WGS 84 most likely)?
If you turn off the DRTK after entering in the manual coordinates it will use the Single averaging and you will have inaccurate data.

I am of limited help with the DRTK, I use Emlid RS2's, the errors seem like you were maybe not using RTK from either it not being on on the drone or the DJI DRTK was using SINGLE.

In Pix 4D, in the images screen (when you first start a project or in Image Properties editor I think), what are the accuracies of your images? THey should be in the low cm range if your had fix and in the meters range if you had SINGLE.

 

[jaja6009]

Some other things to consider:

What is your known point in? WGS84 Geographic with ellipsoid elevations? Or is this in a projected WGS84 UTM?
When importing your images into Pix4D, the coordinates are in the datum and coordinate system that the drone received corrections in.

You also can still post process with PPK, but I only know how to do it with Red Tool Box, although there are other software.
But this will need a Base that can give you access to RINEX logs. Do you have access to a CORS within a reasonable distance preferrably under 20 km?
If so you can buy Red Tool Box for around $100 to $200 US and it will correct your images using PPK referred to the Base where you got your logs.

Your shift in the low meter range still seems like to me that you might not of had a FIX status