How do I know if my normal map setup is correct?

[gazarika]

I know how to setup a corona normal map but how do I know if I need to flip the green or red or swap them I cant tell visually except when its extremely wrong.
any tip?
 

[romullus]

If you can't tell by eye what's wrong and what's right, then usually it doesn't really matter if the green channel is flipped or not :]

[maru]

Unfortunately there is no special way to tell what to flip.

Let's say that you have a normal map with some detail.

If you know whether the detail should be convex or concave, then you can make it work by selecting the right options (e.g. by looking at the whole material - if it's a rock, then it's probably convex; if it's a wall with holes, then it's probably concave).

If you don't know that, then you can't be really sure what options to select, and your only option is to eyeball it.

The software itself can neither tell what the normal map is supposed to represent from context, nor can it eyeball.

Here are some hints on how to work with normal maps and how to find out which options to use (but as explained above, this is not always possible): https://support.chaos.com/hc/en-us/articles/4528320253329-Corona-Normal-Map-3ds-Max