Multiple Bump Map Control

I’d like to be able to use several different bump maps and be able to control the depth of the maps individually. For example, let’s say I have a model of an aircraft. I have a bump map for panel lines, one for rivets, and one for panel warp. Each one needs a different level of intensity or depth. What would be the best method to accomplish this with nodes in Cycles using the Bump node? Also, I have the same question but using the Normal node. Normal seems to produce smoother maps with little banding.

Any help is appreciated.

If you want to combine normal maps you can use the node group in this post:

Thanks Secrop. I was unaware that this process was that tricky. I usually just blend them and call it a day. I wish we had a builtin node for it.

If it’s a bumpmap (grayscale image with value corresponding to the deflection) then it’s not that complicated. I’d be inclined to mix them together as images, potentially using masks to control the impact in different parts of the model, and then run the single image into the bumpmap. It’s kind of hard to visualise since previewing with a shader will look weird, but you can do this with unclipped images (i.e. an “image” map with values larger than 1 and less than 0) using math nodes instead of mixRGB nodes.

If it’s a normal map, as Secrop says, or you’re trying to mix normal data after you’ve run it through a mapping node (i.e. if you want to mix a greyscale bumpmap with an RGB normal map) it gets more complicated. :stuck_out_tongue:

IkariShinji - That’s awesome - I never would have thought of that. Good stuff.

@IkariShinji: Is that advisable compared to just adding the maps together before sending it through a bump mapping node? Does it have any visual benefits?

Why do you ask me? You’re the “node God” around here…:yes:
I’m interested in being able to understand my node setups even in a few months time and still remember what does what. By stacking the Bump nodes together I can easily see which level contributes which bump strength and the results are totally what I expect from that setup.

I’m not at all qualified to decide if this is advisable or not - that’s how I do it and what works for me.
Did I ever see an unwanted effect from it? Nope.
Can I exclude with absolute certainty that negative effects may arise from this under certain conditions? The hell I won’t.

Rofl, node god? :smiley: Thanks, but no way. It’s been like 10-20 years since I last “coded” materials, so I’m pretty much just trying to learn and try to figure out ways around some major obstacles I’m fighting (lack of math and vector nodes/functions/utilities).

I wouldn’t expect any visual “negatives” your way (but there might be my way), the only negative impact would be efficiency and rendering time. There might be a positive visual effect though, which is why I asked, i.e. if bump accuracy is better than float accuracy.

But I haven’t really tried for bump map node, only for shaders. Similarly, no point in blending two glossy shaders with same properties except color (to limit shader calls) when it can be done beforehand in a color mixer.