So I created a small map in Dungeon Alchemist and tried a few different settings to see what did what.
First, the original file is 95.5 GB with 8700*6600
I played around with the size using 2 different settings, 2160p and 1080p
Then I tried 3 different CQ (Constant Quality in the video tab) settings, 4, 22 and 32.
The higher the number, the worse the quality.
Attachment 57857
You can see the differences in the screenshot. The screenshot is from a dual 2160p monitor setup, 4 of the samples are on 1 monitor, the other 2 on the other.
I can see a big difference between 2160p and 1080p but not much difference between the various CQ settings.
I am zoomed in very far though. Zoomed out to see half the map in one big window I don't see much difference between 1080p and 2160p at all.
I would love to upload the maps so you can see for your self but this is where it gets interesting, the file sizes!
95.5 GB - Original DA map
164.5 GB - 2160p / CQ 04
45.2 GB - 2160p / CQ 22
26.5 GB - 2160p / CQ 32
45.2 GB - 1080p / CQ 04
10.8 GB - 1080p / CQ 22
7.5 GB - 1080p / CQ 32
I hope this helps.
BTW, the CQ has to be between 4 and 32 otherwise you get an error.