Import image reduces resolution

Dear Vectornators,

I have a huge game-map (Micro Macro Crime City, 25857x17709 pixels)) which I scanned with my PC in 600dpi using Adobe Photoshop Elements and then merged the smaller parts together. Now I want to color it just for fun and tried to import the image in Goodnotes and Procreate, but the resolution there was too bad to work with.

Then I thought about vectorizing it and found Vectornator as a possible tool on the iPad pro. But each time I import the picture into Vectornator (as new document or via insert photo), it reduces the resolution as well as the other programs, so that I can not redraw the lines accurately. Is there a possibility to change that behaviour?

Kind regards,

PS: This is what the source material looks like:

And this is what Vectornator makes of it:

Hey @Sterndeuter,

We sample images down to max 8K resolution or 4K upon import, depending on the processor. And our vectorizer downscales them once more before trying to vectorize in order to reduce computer resourced needed. And unfortunately it’s not possible to change this behaviour at this time. By any chance you have the pieces of the map as single pieces, so that you can import them one by one instead of the whole big image?