Cycles : Adding the effects of several normal maps ?


How can I add the effects of several normal maps (for instance if I have 3 normal maps : large details, average details and small details). I don’t understand well the logic or math to use.

For instance, here I have a large Voronoi texture (left) and a small Musgrave (right) :

I’ve tried with a MixColor :

It works somehow but I lose part of the deepness of the Voronoi texture.

The only way I’ve found is to connect one of the texture (for instance the Musgrave) to the displacement socket of the material output. It keeps better the valleys and hills of the Voronoi texture but it looks like a quick and dirty fix and it can’t work if I have more normal maps.

So I wonder what’s the correct way. Can anyone help me on that ?

You’re not respecting the color coding. The output of the Bump node is a vector (blue connector). You can’t add vectors precisely with a MixRGB node, which is for color values (yellow connector). To combine vector data it’s better to use a Vector Math node instead:

Another possible solution might be to “stack” the Bump nodes together. I think I have read somewhere that this might cause issues, but I for myself never encountered any:

It’s because of your mix factor. You are only adding half of the contribution of the Voronoi texture - so it appears half as deep as it should if used alone.

You could correct this by doubling the strength on the Voronoi bump - or adding rather than mixing (as the poster above has suggested)

Thanks, I didn"t know the Vector Math node.

Stacking the bump nodes seems working well too. :slight_smile:

Actually the mixRGB is very precise to do math with vectors and coordinates… :slight_smile:

Well, I stand corrected, then…:wink: