NMM - Non metallic metal, metal rendered with ordinary pigments.
TMM - True metallic metal, metal rendered with metallic pigments.

This is a reply to a “NMM vs TMM” thread to the lovely ‘eavier metal Facebook group, a reply that just became too long to post there. So yes, it's a bit of a long read but I think it might be an interesting topic.

I'll start with some theory.

Materials go from very reflective to very matt where reflective materials have little to no subsurface scattering and matt materials have a lot of subsurface scattering. It means that with a reflective surface the light does not enter the material and exits in a nice angle back. Think of it as when you throw a tennis ball at a flat wall. A matt material on the other hand means that the light enters the material and exits in different angles and the light your looking at comes from tennis balls fired from all over the room.

Compare then a mirror to a paper roll, if you move around the mirror everything displayed in the mirror changes, move around the paper roll and the light and dark stays pretty much on the same place on the roll. But why is that if everything is about reflections? Again in the mirror case all the tennis balls are bouncing at you from a particular place but with a matt material the reflections comes from all places, your viewing angle is not relevant any more. That's also why painting matt materials in a realistic way is easier than reflective ones.

The effect of subsurface scattering is a bit like the effect you get if you take an image and blur it over and over again, but with a different cause.

Now I'm probably simplifying but as I see it when we render materials we don't paint so much light and shadows as reflections of light and dark object where a light emitter is the brightest kind of object and a shadow is just a darker object covering a brighter object.

In most display TMM nowadays we semi-fixate the light reflections and fixate the dark reflections while in NMM we fixate both. For a reflective metal neither one tend to look realistic when you start turning the miniature but both can look realistic if you stand still. This might sound strange to you, isn’t that what TMM does? The reflections change and thus it looks more realistic. Yes it looks more like metal, but if the dark parts are fixed, not so much the polished kind.

In the smaller scales, for me, I've seen only one kind of metal rendering that I think looks fully realistic, or at least close to. Meaning with realism that the metal effect works when I hold and turn the miniature and where the reflections are actually behaving as they would on a full size metal object. The metal rendering I'm talking about is grimey, rusty, metals done in TMM where the dark naturally is matt and non reflective. Like a weapon that has not been cleaned properly and only get it's metallic part from wear and tear. 

So if that’s my opinion, do I paint all my miniatures like that? No! Realism is just a style among others, there are many beautiful miniatures that aren’t going for realism at all, or have parts that are and parts that aren’t. I’m talking if it’s good or not, I’m talking realism.

So if we go for other kinds of metal, which one is the most realistic according to me? Well… there are many things to hold in your mind when it comes to realism. For example TMM looks more realistic than NMM in that as it reflects the actual light objects in the room/outside and will have its brightness and color temperature. NMM looks more realistic than TMM in that you can paint the reflections of other objects into the metal (I've only seen it work with other metals in TMM). But the more complex effect you do with NMM, the more clear you do the reflections and the more of your surroundings you take in, the more it will be hard to make NMM look good from different angles.

So both renders have plus and minuses, listed above is only a few.

Why not polish metal if it's supposed to be polished, you say, and get all the reflections? Well because it tends not to look in scale so the miniature looks more like a toy. It breaks the illusion. The larger the miniature, the better this technique tend to look. I've pondered the idea what happens if you build a miniature world around the polished metal. And maybe that will look amazing, if you can ignore the giant face being reflected back at you. I would like to try sometime.

Finally, so my opinion on NMM vs TMM is simple in that I don’t have one. For me it depends on the style and interest of the painter and the style and execution of the sculpt. I love many kinds of styles and I try at least to stay open minded. Staying open minded I think is one recipe for a happier existence. :)

Here some quick shots of my recent WIPs both of NMM and TMM. Feedback is of course warmly welcome. Struggling hard with the bright and reflective NMM I'm going for in the first image while the darker NMM in the second came much easier. Very grimy TMM metal on my Orc Shaman and on my death cult assassin for my INQ28 group it's something in between.

This post is an amalgation of knowledge that I have gotten from programming computer graphics, reading theory about light as well as collecting and painting miniatures. If you see something you think is incorrect on the theory part, let me know.

3 kommentarer:

  1. Excellent discussion! One of my biggest problem is understanding where to put the highlights and shades. And suggestions for a good source to understand where the highlights and shades should be placed? I try to look at pictures of objects when painting metallic surfaces, but that doesn't really teach me how to get the answer, just what the answer is.

  2. Thanks! I am struggling with this too, but I will try to answer anyway. Well metal is very reflective the answer is rooted in your surrounding + the curvature of the metal which will define how the surrounding will be warped. While looking at references helps to start thinking and analysing, but it's just varies too much to really give you a pattern how to think. Honestly it's hard and at least I tend to loose focus too quickly and start painting without thinking. Perhaps I will develop a feel for it eventually, at least I hope I will.

    I think the easiest NMM that looks like metal is, I think to think a bit like when you paint a gem. Meaning a strong light from the top and a softer one from the bottom and then shape the highlights after how the armour is shaped. I employ this in the sword of Thranduil you see above. I usually also colour the light a bit, same colour as my base from below and blue or blue and warm white from above. Can also throw in a glaze or two of other colours.

    There is a great NMM tutorial by Ben Komets when he paints the Stormcast https://www.youtube.com/watch?v=VepXVggrfiE

    Also just take a look at this classic way to think about sketching 2D light http://www.proko.com/shading-light-and-form-basics/ And increase contrast and definition.

  3. Thanks so much! I'll check that link or tonight.