3D Artist: Francesco Furneri
Making Of: Texturing crocodile skin in Substance Painter (first part)
Software: Maya,  Zbrush, Substance Painter, Arnold e Marmoset Toolbag

Project Link: https://www.artstation.com/artwork/oA006W

Hi there, my name is Francesco Furneri and I'm a 3D artist with more than 10 years experience in 3D Computer Graphics and specialized in 3D Modeling and Texturing.

I have worked in 3D companies as modeler, sometimes with the role of technical artist and I am dealing with texturing at the company I currently work with.
At the same time, I have an activity as freelancer in the States, creating 3D organic modeling for characters and props texturing.

In this first part of this article I would like to share some aspects of my last project with you (the Crocodile Project).
I'd like to share the work that I did inside of Substance  Painter, that is the result of materials and texture maps that you see in my renders. Furthermore in the next article, I'll be talking about the lighting and the rendering aspects.

I want to thank treddi.com for giving me the possibility to share this article with you and I really hope that you find this description useful for your ongoing projects.

Introduction


The project was born with the idea to model a 3D crocodile (in particular a Crocodylus porosus), with organic look and proper features of that species.

I wanted to model the crocodile from scratch, starting inside of Maya and creating all the micro details in Zbrush.
Nevertheless, in this article I won't be talking about the modeling as well as the sculpting, as they are quite standard steps. However,  I will deepen the texturing in a way you can follow along and learn some useful tips.

Furthermore, the model has been rigged to be animated in Autodesk Maya.
To whom it may concern, I created a video tutorial where I explain the rig features: https://vimeo.com/471736270

3d crocodile

06ee3f30d52c7e4df5e8f7f4104d2b49.jpg

5e85c2ce8d0b3ca2c56a73e17e21809e.jpg


Substance Painter


As many of you already know, Substance Painter is the ultimate 3D material authoring tool. The goal is to create professional textures and materials to be applied to your 3D mesh. In this project I wanted to laverage the most important features inside of Substance to create cool details on my 3D model.

Why use Substance Painter?

First of all, it's essential to get through the main features that this awesome tool offers:

  • A very intuitive approach based on Layers (it slightly reminds Photoshop) and with a non destructive workflow: that means you can create and edit part of the work done,  without compromising the whole structure. It's a bit similar to Substance Designer or Houdini in terms of  procedural aspects and some of them (like Substance Designer) are node based to manage the changes with ease.
  • A  large set of brushes and particle brushes that react to physics (e.g. varnish pouring down a wall).
  • A big library of procedural maps like dirt, grunge maps to name a few.
  • A texture baker, that comes with Substance, with the possibility to generate output and intermediate textures: the latters will be used during the texturing to improve the quality of the final result. I will be explaining more about that in this article.
  • The use of smart masks which detect part of the model (according to some baked textures) and allowing you to add details there.
  • The use of materials and smart materials.

.. and again.. Alpha, stencils  and other cool features.

For time's sake, I won't be discussing all the previous features because this is not a Substance Painter course!
I will only detail some aspects connected with my project.

This is the main interface I worked with:

99aec402f9615df2b922457bad6a9389.jpg

On the right panel (in blue) there is the Layers section which we'll describe in a minute.

In my workflow, I usually start off with a Fill Layer and I build up all the color variations on that with a stack of layers.
In order to study the crocodile, I took advantage of different photo references by finding some key colors: I used a yellow/brown color (with more saturated variants) to paint the lower part of the body, while I applied cool hues for the upper part, starting with a grey / dark blue, to finally have the results shown in my renders.

Furthmore, I decided to introduce some green shades, expecially to add some small details in the concave areas (for instance the result of algae and dirt around the croco scales).
Then, I chose a very well defined and basic color palette like in the following image:

7d469587998497fa8a79fba881e31679.

I organized my project in folders:

  • Head Details
  • Tail Details
  • Upper Part
  • Yellow Part

with some Adjustment Layers at the top of the list to tweak some parts.

Finally, I worked on the roughness map that will be described at the end of the first article.

Every folder contains different layers with applied masks, adjustment paint layers to manually paint or modify the mask, etc.. 

Let's see now what the folders contain.

Exploring the layers (the lower part)


Let's get started with a clean crocodile, with just a normal map applied which has been baked in  Zbrush.
As I said before, Substance Painter is also a texture baker and responsable for producing useful texture maps: the entire process is called texture baking.
Before talking about texturing, the baker creates the following maps:

  • Curvature Map: it represents the convex and the concave areas where we can add details like dirt, for instance.
  • Thickness Map: this map measures how thick or thin a part of a mesh is and it's often used to create some SSS effects (Subsurface scattering).
  • Ambient Occlusion Map: it creates soft shadows in occluded areas of the model. It's also used to add details in those parts.
  • Position Map: a map that stores the vertical position of the mesh (its height from the ground). It is generally used to add details along a specific direction (expecially the y direction).

If the goal of the previous maps is not so clear at the moment, I'm sure you will understand better in the folllowing part of the article.
For now, consider them as Utility Maps, that are created to simplify the texturing: for instance it would be hard to manually select the concave parts of a model; with a Curvature map, you have them stored and ready to use as masks to add dirt and details in those parts. 


a09c46f4f9bc38a200431c5630428f1b.jpg

Let's consider now the folder named Yellow Part.

From bottom up it contains the following layers:

  • YellowBase: the base color to apply to the model 
  • Brown Occlusion: a layer to add details in occluded areas of the model
  • Cavities: a layer to insert color variations and dirt between a scale and another
  • Dark Cavities: a layer to boost the presence of color variations in concave areas and to make the albedo more interesting

Everything is then filtered to create a smooth transition between convex and concave parts.

We now add more layers to have a first result.

Consider that a specific layer may contain sub layers with filters, adjustment paint layers, generators, procedural maps, etc.. these effects are applied to create a custom level mask.
For instance, the layer called BrownOcclusion (in the following figure), inserts brown hues in occluded areas. As first step, I load the Ambient Occlusion Map which is shown besides the color slot and is associated with the sub layer Fill, then I add an effect to modify the histogram of the mask (Levels), and finally I apply a Paint Layer to manually paint my custom mask.

It should be clear how the BrownOcclusion layer works with the Ambient Occlusion mask and the sub layers: I choose the brown color and I reveal it in the brighter areas of the mask. The mask is the result of the baked AO, with an histogram effect and with a manual painting.

In the dark areas of the mask, the color from the below YellowBase is used: as blending mode I used normal, which is simply an alpha blending like in Photoshop.

PS. Always consider the layers from bottom up.

To sum up, Adding details in cavities (e.g. Cavities Layer) follows a similar approach: we start from a base color, we add a Curvature Map as layer mask;
the mask is then modified by filters, histograms, generators, in order to produce a custom one.
At the end, the bright areas takes the current color of the layer, while the dark parts blend with the layers below, according to the applied blending mode.

Just for the record, the generators change the appearance of a mask by analyzing our baked maps: The interface has sliders to set the influence of each of the maps to determine the final look of the mask.
Instead, the smart masks, are similar to generators but they work for specific purposes (e.g. a  dirt occlusion smart mask automatically uses the ambient occlusion to determine the occluded area).
On the other hand, the generators work in a more generic way.

You can also use a combination of procedural maps (e.g. grunge maps) to create highly customized level masks.

36ed14a6fe3e38f309dfef38a7e0f2e7.jpg

0f6b457f76aa4b9108b966da49750a8c.jpg

b807f22acb09eb48275c7d5b572557d9.jpg

0cf2289bd372b59b5987697ecbb32712.jpg

I wanted to detail the parts between the scales, where typically dirt and other elements are likely to accumulate.
For the other layers, the process involving the texturing is almost the same but we'll see some other examples to add details.

Exploring the layers (the upper part)


For the upper part of my model, I looked at difference references to decide what details to add.

Keep in mind that crocodiles live most of their life in swamps and marshy lands, thus it's not difficult to find some residual greeny parts in their body , for the presence of wet leaves, algae and other natural elements.
For that reason, my goal was to add the effect of those elements on some parts of the model, without exaggeration.

d6161c76230ebcbc83f8fdba3d074fad.jpg


76e1c1dfcbacd8145521ed2240f75507.jpg


You can easily see green residues and other elements on the scales, as well as in other areas (Algae and Dirt in cavities).

On some scales, I decided to create some irregular patterns,  giving a breakup with white / creamy color that blends with a dark blue hue (Color Breakup).
Furthermore, on other scales, I added a Dotted pattern (e.g. the rear paw)  that is one of the features, amongst others, that  makes crocodiles different from alligators.

a0fb391f2e1ce825f6f58e17d4c34e98.jpg


I started off from a BaseColor with a dark blue shade and I added some details in the cavities little by little, in the same way I did before.
Afterwards, I added some green parts (e.g. GreenBase. DirtyAlgae) based on custom masks that I'll show you right now: the white parts of the mask are related to the presence of algae and they are located between scales, in occluded areas, towards the crocodile's belly where the model touches the ground.

In general, notice that during the creation of the mask, I used a mix of both procedural maps (grunge, etc.) and adjustment paint layers to manually add or remove some parts.

73845047a8468b3727ef1a283db21ab8.jpg

257c2ed6fb2b45f18878e3133303220c.jpg

About the White Dots and irregular shapes, I used brushes with a more organic look, to break up the base color: the shapes also contain stiggy lines and resemble the mottling pass that artists use for texturing characters.

1e0bc7af4b6b73e45715e7ebf054a513.jpg

Bear in mind that texturing is essentially connected with the blending between layers: the use of masks guarantees that one layer is put on top of each other in a smooth and integrated way.

Finally, to add more breakup to the parts (Breaking up white), I created a mask starting from a procedural pattern (ratio_crystal_1), blended with another map (ratio_grunge_map_014). I then modified the histogram and I manually painted the mask with a Paint Layer.
The pattern reminds the presence of pale patches, which are visible in some crocodilian species.

26e51768096aad49ad1012ee33f992b2.jpg


Tail Details


The tail approximately follows the same principles explained before: we start with a base color, we add a series of generators, adjustment layers, paint layers, etc... to create custom masks and to overlay the layers properly.

236b24579b694814153ee2f8a9e128fd.jpg

As you can see, I kept the layer called Yellow Part but I masked some areas out, by  producing random vertical stripes.
On top of those stripes, I added elements such as dirt, some green color (to remind the algae) and I generally emphasized the separation between scales by adding a dark color.

If you look at the surface of the some scales, you can notice the dirt following a vertical direction, as if it was almost a leaking effect that I observed in real photos.
A word of advice, apart from collecting photo references, is to think about creatures, as well as objects in real world, as elements living in an environment, and because of that they interact with the nature: for example, the green and the dirt suggest that my crocodile comes from a swampy territory, in strict contact with a dirty terrain and that makes it more natural and real.
Some artists underestimate those details and they simply start by painting one color on top of each other without a proper observation.
If it's true that the work might be a bit longer, it's also true that you will get subtle but interesting details at the end of the process.


Head Details


The head, like the upper body, was the part that took me some time to complete.

This crocodile has the visible presence of some irregular scales on the lower part of the mouth (starting from the jaw). On that part, there are also black dots and some green elements: I observed that feature in my species (Crocodylus porosus) but not all the species share the same pattern.

6d89b04e6ce5512dda3068fbc43f32e5.jpg


For the lower mouth, here are the levels applied:

2fba1a8e9bbed7e68695b17c68a01cb3.jpg

Mouth Lines is created from a Fill Layer with my curvature map.
I then add adjustments to my histogram (Levels) to invert the selection and to select the concave parts.
I add a blur filter to smooth the mask out.
At the end I use a Paint layer to manually remove part of the mask, expecially on the scale surface: that's because my curvature map also keep some areas on the surface but in this case I just need the part close to the edge.

This is my final mask after applying my changes:

568c0dc9fd3e95df82bbc808f19cd18c.jpg

The Mouth Lines layer has a brown color.

I also have a layer called Algae that uses generators and procedural map with a cloud look, to detect some areas in the edge and to add some randomness in the distribution with a cloud noise.
To randomize more I added a Paint Layer on the top of the list to have more control over the part with and without the green color.

3901e718a9c6a326e59e9ac28aff714e.jpg

In the last layer, which is the simplest one, called Black dots, I added small dots on the scales: this is achieved by painting dots on the level mask: the white part of the mask reveals the color.
With the Black dots layer, I could have simply used a Paint Layer without adding a mask, because they are just brown dots on a surface.
The reason behind that is quite simple, as I want to have a non destructive workflow: if I ever decided to change the dot color in a second moment, or to change the roughness value, with the use of a mask everything would be very easy, whereas with a simple Paint Layer that wouldn't be possible unless  you decided to repaint the dots from scratch.
As you see, even for very simple layers, the mask is very powerful.

c90a70f0a88a7588e950492c65014f1b.jpg


For the Inner Mouth Details these are the layers:

5931e1fd339c68e19e39a2858bcda3b6.jpg

Without going too much into details, I tried to isolate the mouth with a custom mask.
Generally, the crocodile's mouth has colors that go from light brown, yellow to a soft red / orange, created with the Soft Brown and Soft Orange layers.
Differently from what one may think, the inner mouth doesn't have vivid colors and, even in some species, the dominant color is a very pale yellow.
With a Concave layer, as the name suggests, I wanted to emphasize the concave parts by putting some more organic red.
Finally, a small amount of blue color (Bluish Contrast) at 38%, with a multiply blending mode, was essential to cut some saturated areas and to add more contrast in some parts of the mouth.

e98e1cb332f7119cb1947ccdf13b3410.jpg

Around the teeth there is a dirt layer to make that part more realistic and with a more natural transition to the gums: it's easy that the tooth base has some residues and dirt.
Furthermore, for the teeth and nails (that I won't discuss in this article), I followed a similar technique with masks, overlay of procedural maps and generators.

An interesting detail that I wanted to add to the upper mouth, is the presence of yellow stains that run along the side part of the mouth.

Some species have that pattern in other area of the body too; some others, have the entire body covered by those stains.
For instance, I also re applied the same soft pattern on the rear paws.

e4d7eb39e330a049232576927d297d72.jpg

To achieve the result that you see above, I used a procedural pattern with the control over the distribution and without repetition.
After some studies, I found the ratio_crystal_1 map interesting to apply and I used it on the entire mesh.
The benefit of working with layers is that you can decide how and where to apply the textures but also, you can modify the distribution and, in a second time, you can limit the texture to particular areas.


13ef628eba7604af9fcaa5618c098d39.jpg

Here is the global application of the ratio_crystal_1 map on the crocodile

f12c89a5b984cbdd13254d8f69883cce.jpg

With just one map applies, you can easily notice that, apart from the chaotic result, the pattern has a sort of repetition, that is not what we want.
Furthermore the mask intensity is too much for our purposes.
The use of procedural maps have to be planned with attention, because without the option called triplanar projection you might find some texture seams that breaks the continuity of the procedural pattern.
While modeling the character is better to position those seams in hidden areas of the model: Substance Painter comes in handy with the triplanar projection but it's a good habit to always hide unwanted seams.
Another solution to remove the seams is simply adding an adjustment paint layer to the mask and paint on the seam to reset the continuity.

Getting back to the yellow stains, as second effect, I applied a change to the histogram (Levels) to change some black and white values and I applied a Fill Layer with the usual curvature map to limit the effect but, this time, on the surface of the scale and not in-between.
The result now is much better.

fa2ea61e1e308c569226e9acb6695b31.jpg

I have now a more interesting distribution, less strong and with not just black and white but with a intermediate brightness.

Finally, I applied an adjustment Fill Layer to manually choose where to add the stains, to smooth the intensity with the advantage of deleting some parts and to make the distribution more natural.

fac3550c912595f618f25d8aa6723efd.jpg

The result, blended with the other layers, has a soft but cool presence of random stains.

You can easily notice how the stains have been painted on other parts of the crocodile's body because the layer acts globally on the mesh.

a7284a6b9c039c410c3eea275a2d0914.jpg

A last note about the masks, involves the possibility to restore the pattern on specific areas if accidentally deleted.

In the example, if I manually delete a part of the mask, I can always restore it with the Eraser in Substance Painter: I have to select the adjstument layer, activate the eraser and then I paint on the area where I want my distribution back.

With this last part I've finished talking about the texturing.

In the next paragraph I will give you some tips about the roughness map.

The roughness map


As explained in the awesome book "PBR Guide" by Wes McDermott( that I strongly recommend to read) the generation of a roughness map is a creative process without many constrains that requires creativity, as well as the other texture maps.
It's not always easy to understand how an object reflects the light in a specular way: on one hand because the result depends on the light sources that interact with it and, on the other hand, it's not always possible to phyisically have the object in your hands.

Here is the case of the crocodile that is not present in my territory (Italy) thus it was not possibile to observe it directly.

Photo references and expecially videos come in hand to observe the animal as he moves.

The crocodile, in addition, is an animal living in the water as well as on the earth and the roughness values  can be different in some conditions, due to the water droplets and the humidy on the body.

In my case I tested out different roughness values and I finally used one that better reflects my renders and the some real examples in nature.


I'll show you now my workflow used for the roughness in Substance Painter.

1bfe960a64d019a4769b4428d2b53841.jpg


There are many ways to generate a roughness map.
If you look at real photo references, you can see that in occluded areas (in my case between one scale and another) the reflection has an higher value (imagine that there is dirt and other material there) and the concave areas have a dimmer reflection for the presence of self occlusion in those narrow areas.

With that in mind, we can deduct that the surface on the scale, instead, have the roughness with a lower value (and with a more concentrated reflection).
The roughness I'm referring to is based on the Microfacets theory by Cook- Torrance.

That being said, the first layer that I created, called no reflection in cavities, follows that hypothesis.

I also used the curvature map to mask the concave areas and I applied a blur filter to smooth the mask.

a2da167b16d5e1239857fe35808332df.jpg

Consider the white color of the mask between the scales (high values) that has less reflection than the area on the scales.

The created map has a range of well distributed values but we can improve the breakup by adding another layer with a procedural map (Cloud Breakup).
In this case I used Cloud 3.
I can always add an adjustment paint layer with manual painting.

Finally, I insert a simple layer (freehand roughness) to give more creativity to the mask with a simple brush.

7115e8bbab054a7d5bc8b0a03baee94e.jpg

Note that the reflection is visibile on the scales and we practically see small or very low reflection between the scales.

I repeat, the roughness map is up to you and it must be created with your own creativity and knowledge and by observing the reality as much as you can.

In my renders, I also tested high roughness levels to have a dry look and appeal and, in the future, it would be interesting to create a roughness map with lower values, to represent the crocodile just out of the water.

This is the roughness map projected on my UVs.

6f97ce1fa6e3384335bdc1952797f204.jpg


Before finishing the article I would like to leave you with some bits of advice,  to encourage you with texturing and with Substance Painter.

Final bits of advice


  • Before starting your work, spend part of your time by collecting photo references: at first take as many photos as possible, then reduce the set to few pictures that better describe your idea;
  • Texturing a character,  a prop or whatever is not just using layers but is essentially trying, deleting, redoing and refining your results until you come up with something cool;
  • Dont' worry about the number of procedural maps, brushes and masks in Substance Painter. With just few brushes and options, but with clear ideas, you can reach excellent results;
  • While texturing your character, set an environment map with a natural illumination, avoiding many light sources with different color temperatures, saturated colors, etc.. The more natural, the easier the texturing process because your albedo color map will be more similar to the color that you see in a real environment and you won't be deceived by "fake" diffuse colors;
  • As you've seen, masks play an important role in texturing. Learn to produce new creative masks,  to use generators, paint layers, etc... don't simply use existing mask in Substance Painter but create your own art;
  • Sometimes you may start the work with Smart Materials, which are presets of materials with layers that use your baked textures to simulate particular surfaces. You can then modify the smart material and have something custom;
  • Substance Painter has a set of filters to use on masks for instance. You could apply a blur effect or modify the brightness and the saturation of a texture and much more! Try and have fun!
  • Substance Painter has also many particle brushes that reacts to gravity, normal map influence, life span of the particles and many other parameters. In some cases it is worth using them.

We've come to the conclusion of this first part where we talked about the texturing.

In the next article, we'll be talking about lighting and rendering.

For any question, drop me a line at jackfurneri1984@gmail.com

Stay tuned and see you soon!