Frustration

Recently, I’ve been frustrated with my shaders.

None of them look the way I want them to. I’d like to achieve a painterly appearance, or watercolour, but they’re quite elaborate. I sometimes think it would be better if I could settle for cel shading, but I just can’t accept that. Or rather, I want to be able to do more than just shade everything so simply. I’m not one of those people who’s interested in NPR primarily, or purely, to replicate the style of anime. It’s not that I look down on that style; it’s just not my preference.

So, I’ve been doing more research, as usual. The big problem with using Fresnel or Layer Weight to make the rough shape of the object, or an outline, is that it can give unwanted lines, and does. I dislike having to manually correct these, so I’ve been trying to think of ways to fix this. I’ve experimented the day or so with blurring the normals of the model to remove details.

How did I do this? Well, I’m not blurring the normals, exactly. I came across this video a while back. One of the features demonstrated is creating a false blur by distorting a texture.

23:58 for the blur technique.

I’d hoped I could apply the same technique straight to the normals, but it didn’t work. Instead, I baked the object’s original normals out to an image, and used that method to distort it.

The result was effective, actually. I haven’t removed anything from the default Suzanne head, but by blurring it and using it as the Normal input, it’s removed the detail. It also darkened it for some reason, which I was able to compensate for by remapping the value by an equal amount to the distortion. I’d hoped to use this to get a blurred version of Fresnel I could use to make a better silhouette. However, when I tried it..

It only works from the front. I really don’t know why this is. My best guess is that it’s something to do with the normals’ texture. The colours don’t appear the same way when I look at them as the original normals do, so perhaps it’s a reason why it doesn’t display right. However, when I used it as the normals without blurring, it displayed correctly.

It’s quite frustrating. But at least I learned I can blur out detail with this method. That’ll likely come in useful.

The advantage of this method is that the original normals are a texture that isn’t being permanently modified, so it can be controlled as I please.

The disadvantage is, it’s grainy. I haven’t found a way to smooth it yet, though, for what I’m doing, a bit of grain may help it appear natural. Also, as it’s just using the original normals from a texture, it can’t be modified the way the real normals of the geometry can.

On another note, I came across an interesting method for modifying shading.

This technique comes up ~ 1 hour, 15 minutes in.

This one uses an image texture to paint on to control shading. The trick is to create a UV slot on the objects you want to modify, and then use the UV Project modifier to project UVs, like the Project From View UV mapping option, but in real time. Then, have an image texture using that UV to control the shading by adding or subtracting. As they’ll all reference the same image, you don’t need to select individual objects to control, and can modify everything in the shot at once.

The advantage of this method is that you can control them all at once as long as they’re referencing the texture. Additionally, if you make it the same resolution as your render – and you probably should – it shouldn’t appear pixelated. And since it’s an image, you could also edit it externally if you really needed to or wanted to. I find this method far more responsive as I paint than modifying vertex paint, and it can be far more precise than vertex paint would be on most sensible meshes. It’s extremely effective for cel shading.

The disadvantages are several. For one, it’s an image, so it’ll bloat your file size, potentially a lot if you’re rendering at high resolution. Also, because it’s an image, you can’t animate it the same way you could the vertex paint method; you’d have to use an image sequence, increasing the file size further and manually repainting each frame. Although, if replicating anime, that may be best, as it’s essentially what colouring in anime is like, and leaves room for human errors that make it appear more genuine. Lastly, if you change anything in the shot, you’ll have to repaint. Depending on the change, this can be small or large; if you move the camera, you’d have to redo the lot, or, if you were just panning, perhaps you could compensate using the Mapping Node or translation method. That makes it tricky if you want to change the camera angle or re-pose a character or such, though if you modify the shading last, it shouldn’t be as much of an issue. It’s also more difficult to make look natural on something with smooth shading.

Overall, I find there are advantages and disadvantages to this method, but it’s certainly something I’ll keep in mind. I might well use it next time I’m doing a render; I prefer the flexibility of vertex paint, being able to modify things after the fact and the shading changes not be rendered all worthless…But the speed and precision of this texture method isn’t something I can ignore. Custom shading is very likely the key to convincing 2d, or at least an essential.

Anyway, that’s what my research and testing has turned up for the moment. I want to experiment more. Reading a reference from an old Siggraph paper, Painting With Polygons, Video Watercolorization using Bidirectional Texture Advection gave me some ideas; that’s actually where my idea to blur the normals came from. It also seems several steps of their process are ones I’d used in my earlier compositing technique, though applied differently. I’ll try experimenting more and see what I can turn up.

Yankumi

Recently, Millie and I have been watching Gokusen.

I wanted to make some fan art of Yankumi, so I took the time to try doing a study of her actress, Yukie Nakama’s face. I didn’t end up making it look right in the end, though. I lost her likeness somewhere along the way, but I really wanted to get something done, so I pushed through regardless.

Unfortunately, I’m not happy with how it turned out. The proportions aren’t right, and I wasn’t able to rig it correctly. Or rather, I didn’t want to spend the time needed on finicky bits like faces and hands. I need to get better or quicker at them.

I also couldn’t get my shader to work right. It didn’t work well when applied to her model; I’m considering going back to the start with it. I’ve been reading up on painting techniques recently and thinking about how I might apply those in my work.

I just used Freestyle, so the linework isn’t great. I also wasn’t able to deform the clothes mesh the way I wanted to make creases; I’ll have to revise the technique I was planning to use.

On another note, I recently discovered a comic book artist called Brian Haberlin. He’s currently using 3d art in Sonata and The Marked.

The Marked # 2 (Left), Sonata #1 (Right)

It’s encouraging to see successful artists making use of 3d. I searched for information about him online, and found a video he did some time ago on YouTube demonstrating his techniques.

I was disappointed, though. I learned he mostly uses models purchased online, and then retools them as he needs,or even just uses their default controls to give specific likenesses.

I can see the benefit of that in terms of time and effort, but…It’s not very artistic to me. Where’s his own style in a model he bought from someone else? Appropriating other assets and modifying them to your purposes…I don’t think it leaves a fingerprint the way something you’ve made yourself does. And that may be good for technical quality, depending on whether an artist making everything from scratch is skilled or not, but if technical quality was all that mattered we could just stage photos using real people and take those to make comics. Style and personal distinction are hugely important, at least to me. So, while I can understand benefits like consistency and time saving, I don’t agree with using models like that. It doesn’t feel right to me to just buy stuff to adapt like that, and misses out on the artist’s own style.

I was also disappointed to see the simplicity of the technique. He uses Poser, and it’s just the inverted hull outline method, a black and white colour ramp, and texture maps for lines on the model. I hoped there would be something to learn there that I didn’t already know about, at least as far as shaders go.

I also noted the difference colour can make. Sonata uses more gradual shading and colour variation, and it disguises the 3d better. The Marked is using more high contrast shading, pretty much cel shading, and it reveals the ugly telltale shading of 3d a lot more because of that. I suspect it may even have been rendered straight out, rather than coloured in 2d, judging by the shape of it.

All in all, I need to work more and get better. I need to nail down my own techniques and work out how to create the look(s) I want, and efficiently, and learn more about making things like clothes and rigging.

Shader Experiments and Improvement Attempts

My previous renders highlighted a problem I’d not thought of while modeling them.

The soft edges look fine against only the white background. They appear soft and match it nicely, giving at least part of the look I’m going for. But, it doesn’t work with environments, or anything behind the object that doesn’t match the colour of the “canvas”, the white colour that’s being mixed with the object colour.

So, to fix that, I’ve been experimenting with replacing that white edge with transparency.

I tried using the alpha blending mode Hashed first. But I had that the problem of the interior’s faces being visible. That makes a more even silhouette, except that the lines of the front highlight the hole, making it appear more 3D. Hashed is also much noisier; even when I rendered with high samples it appeared grainy.

Note that this image is from behind, not flipped.

I also found the transparency worked too well this way; you could see through the model from one side and out the other. Looking at it from behind, I could see the eye that should only be visible from the front. Thinking of it as something to imitate 2d, this is very wrong; a silhouette in 2d is just a flat shape without depth. You should only be able to see the side facing the camera. I tried to correct this by making the backfaces also transparent, but this lead to some undesirable behaviour, too, like the empty eye socket rendering as a hole. Although, to have it both ways there is impossible, and ideally I wouldn’t have any backfaces showing to the camera to begin with.

In any case, Hashed turned out to be insufficient, so I tried Blend, but it has the same problem. It’s less noisy, at least. I suspect my colour ramp controlling the Alpha is at fault for being too weak, in part. But I need some method to get rid of the faces on the other side of the object; to hide what shouldn’t be seen.

After that, I experimented more with how I was making my silhouette, for a change of pace.

I have another method besides the Fresnel to product the rough shape of an object, using the Normals and Location/Position. I quite like the way this one looks. It’s soft and easy to work with. It’s not as specific as Fresnel or Layer Weight on the edges, which makes it easier to make it look 2d. But that’s also a disadvantage; I have do more to make it match the basic shape of some objects. The rough person-shape I made on the right, for example, has much less colour on the limbs. I also found this wasn’t compatible with my current method of texturing the edges, so they’re too smooth and perfectly neat.

It subtracts the Location from the Position so that when it’s moved in the world the values won’t change. The Scale vector is plugged into Normalise from a previous setup I forgot to disconnect. The cross product with the incoming is what allows it to change with the view.

In the end, I concluded that that doesn’t work for me at the moment. It’s too incompatible with previous node groups I’ve made, and I’d like to be able to reuse them as much as possible. It’s also too much work to make that into a generally accurate silhouette. The trouble with the Fresnel method, on the other hand, is that it starts out too accurate and has to be manually modified.

My current stage of the shader, part-way through modification.

I could use a simpler mesh and the Data Transfer modifier with weights to give a simpler silhouette, but it increases the amount of work to make a character, or other object a default Fresnel edge won’t work well on. I’ll continue to look for methods to improve it.

Dragon Knights And Perfectionism

I’ve been having quite a problem making things for a while.

I like to sculpt, and work on new NPR techniques, and I want to show the ships and characters I like well, but in the end, I haven’t ended up posting anything in a long time. I ended up stuck in a crappy perfectionist mindset, always revising or redoing things, or procrastinating from them because I was afraid of getting it wrong, or that it wouldn’t be good enough. But because of that, I didn’t do anything. I don’t have anything finished to show for my sculpting and shaders. But I was encouraged by my friend recently to try and dial it back, and do simpler things and work my way up, and to try and work on my perfectionism, so I’m trying.

I’ve started with chibis. They’re a lot simpler to model and rig than realistically styled characters. I’ve also been finding they’re easier to shade, to an extent; it might be because they don’t have as many bulges and creases and things that can go wrong and look incorrect. Still, I wasn’t able to make them look the way I wanted them to yet. My shaders need more work.

But, I made something. It feels good to have done that, at least.

Millie and I were talking about our Mirror! AU, in which traits of Yugioh characters are reversed, resulting in very different relationships. Jounouchi and Kaiba (we call him Seto in that au, since he prefers to be friendly and warm) are friends, and we had a headcanon that Jounouchi and Seto game together. Millie also made a cute comic about it. It inspired me to imagine them playing an MMO or something together as Dragon Knights, similar to the Dragoons from Final Fantasy.

Since their signature cards in Yugioh are the Blue Eyes White Dragon (BEWD) and Red Eyes Black Dragon (REBD) I designed them to be reminiscent of those, and similar to the Monster World figures from the manga and Toei anime’s Monster World arc.

My design for Dragon Knights Seto and Jounouchi. I’m not a skilled 2d artist.

Then I modeled and rendered them. I’m not very happy with the render, but it’s something; I’ll have to play with their shaders some more, and learn to make environments. Even a very simple one, like the grass they’re standing in was unfamiliar to me. I’ve spent so long doing characters and being a perfectionist about them, I’ve neglected other areas.

I’m not very satisfied overall with it, but I’m glad I finally did something. I’m grateful to Millie for pushing me to do something like this. I’ll also make a post for myself about what’s currently going right and wrong with the shaders, and what I want to do to improve them. I’ll try and build momentum and make more things, too.

NPR Shader Experiments 01

I’ve been experimenting for the last few days with more shaders, using Eevee in Blender 2.8. I started trying to replicate my previous compositing effect, then ended up doing something a bit different.

As I can’t use Dilate/Erode with shaders to get a soft edge, I used a Layer Weight node. I wanted to use the Bump node to modify the normals to gain control over how that turned out, using vertex paint to define which normals are bumped, but it ended up displaying incorrectly, so my current solution is to use vertex paint to add or remove colour from the initial appearance, with a second set of vertex paint to modify the shading. I like this method better than using modified normals; I can directly control it, rather than just having to change normals and hope the outcome is correct, or having to change them frequently depending on the lighting or model angle. However, unlike Blender Internal, I can’t currently get a difference in the shader between its own shadows and shadows cast on it by other things, so if I modified the shading for being ugly in an area shadowed by a second object and itself, it would erase the other’s shadow, looking incorrect.

But, if the AnimAll addon is upgraded to work with Blender 2.8, the vertex data will make it animatable, meaning I could easily fix shading every frame. Currently, that addon isn’t compatible with Blender 2.8, though.

I also used a small amount of bump mapping to add a little bit of inconsistency and texture to the models; complete perfection in the shading is a big tell of 3D. I also used a noise texture on the edges of the Layer Weight’s result, to make the imperfect.

I have to work more on this; I think it’s better to combine some of the vertex paint effects, for one. If I’m changing the shading, it should also effect the edge. As it stands, shding that’s removed doesn’t overwrite the original Layer Weight result, so it can cause areas to exist that look too dark next to modified shading. Also, I need to see how it works with different colours. Past experiments have shown dark colours, high saturation, low saturation, behave differently, so I may need to modify how strongly they’re visible according to those to make it look good. I’m making progress, though. I’ll also experiment with applying this to proper models instead of test models, since the purpose is to be actually usable.

Mirror Ryou and Painterly Compositing

A few month few months ago, after having used Cycles for a while, I was frustrated by its lack of support for NPR features. Being designed for realistic rendering, it didn’t lend itself well to stylised renders. But I came across this post in a thread on BlenderArtists, which inspired me to consider ways to use the compositor.

A watercolour and pencil render using Blender’s compositor, by System on the BlenderArtists forum.

So I spent a few weeks trying to work out various ways I could use it. My aim was to create a painterly style, or some approximation of it, using the compositor.

I started by replicating that affect to familiarise myself with it, then doing my own thing from there. After having spent several weeks trying different thing, I came up with my own effect, and became very familiar with the advantages and disadvantages of using the compositor to create NPR renders.

The advantages:

Compositor changes are relatively quick, and don’t need you to re-render an entre scene, saving a lot of time.
Compositor changes allow you to affect the image as a 2D render, rather than having to work out how to make things work in 3d.
Compositor changes allow you to use some functions that aren’t available for shaders, such as Dilate/Erode, Sharpen/Soften, Sobel, etc.
Using the Compositor allows you to texture an entire image in one go, rather than having to apply it to everything.
Allows access to many render passes, allowing you a lot of flexibility.

The disadvantages:

Each change takes several seconds to show, particularly with complex compositing.
One size especially doesn’t fit all; different scenes, such as bright, dim, interior, exterior, may require significant changes to the compositing to look good, or even maintain a similar appearance.
No convenient way to control the main and shadow colours of individual objects.
Any change, such as rotating a light, changing size, character posing, etc, will require being re-rendered before the compositing can be tweaked; an issue with shaders, as well.
Inconvenient to pull from one file to another; shaders on a 3d model would just come with it when appended.
Entirely after the fact; it’s manipulation of render passes after they’ve been rendered to try and change them into the desired result, rather than a shader-based method which would likely be designed to ensure the renderer gives the correct result each time.

After a lot of experimenting, I was able to come up with this render of a 3d model I made of Mirror! Ryou, an au version of a Yugioh character that my friend Milliekou and I came up with.

Mirror! Ryou, rendered in Cycles, modified in the compositor, using Freestyle for the lines.

A gif showing the key stages in my compositing. This model is old now.

My process starts by doing the usual render.
Then, I get the shading Value by dividing the Value of the original image by the combined Value of the Diffuse, Glossy, etc, passes, which I can use as a factor later.
Using the Ambient Occlusion pass and Dilate/Erode nodes, I make a mask and mix the background colour with the original colour of the mesh to fill the general shape of the character, giving it soft edges.
I also got the light colour on the object, multiplying it with the original colours and then using the shading Value through a colour ramp to make the main shading on the model. I also used the Dilate/Erode tool to make it less perfectly accurate, as perfectly accurate shading is a dead giveaway.
For some texture – a key element, I’ve found, of making something look imperfect and not like a 3d model – I massively sharpened the original shading Value, dilated it, then used a Sobel filter, giving it many rings, that I then multiplied the image with to create some texture and imperfection.

I made some errors here; his belt, for example, should be glossy, but I didn’t combine the passes correctly. But overall I’m pleased with the effect, and would like to replicate it in the future. I want to make it more reliable to be able to make lots more images with that style and perfect it. Although, I’m currently waiting for Blender 2.8 to come out official and get more render passes; being able to replicate this with Eevee, if possible, would be extremely helpful. In the meantime, I’m experimenting against with NPR shaders using it, as it allows many more options. I’ll have another post later about my results with that, and hopefully some more actual art. Ultimately, I’ve found the compositor warrants more investigation, and can be a powerful tool, as long as you realise you’re working around Cycles, not with it.