Alternative workflow to RedEdge plus PPK

It is possible to georeference a NDVI map using the more accurate PPK RX1 map. I elaborate two ways how it can be done. Either directly in Pix4D or by using a GIS software for an additional processing step.

Pix4D variant:
You can process both projects separately in Pix4D. Afterwards you can create manual tie points in the accurately located PPK map and use them in the RedEdge project as accurate 3D GCPs. A more detailed description can be found here: https://support.pix4d.com/hc/en-us/articles/204373409-How-to-align-projects

GIS variant:
For this workflow you process both maps separately in for example Pix4D. The output maps can than be imported into any GIS software as new raster layers. You can use any GIS software to georeference raster layers. I add here two links that explain how it is done in the open source software QGIS. 
https://www.qgistutorials.com/en/docs/advanced_georeferencing.html
https://docs.qgis.org/2.18/en/docs/user_manual/plugins/plugins_georeferencer.html

Both methods explained above presume that you find distinctive points in both maps. That means you need to make sure to not only cover fields or forest but you also need to see some buildings or streets with road marking or duct covers on both maps.

I hope these explanation and links help you to establish a workflow to accurately georeference RedEdge maps. If you have further questions, feel free to contact us. We can also set up a call to clarify open questions.