Research and Preparation (2:00):
The look development represents my principal area of interest in CG and creating sub-surface
scattering materials has always been a challenge for me. For this reason I considered that
taking a closer look on human skin is a great opportunity to improve my knowledge in this field.
Before jumping into the texturing and shading process I decided to do my scientific and artistic
research about skin. There is a lot of information available which can be applied in CG and that
is critical to know in order to achieve production quality results. I will describe these details as I
go but first I will talk a bit about the preparation behind my texturing process:
For getting the best results we need to use projection textures that resemble the color of the
skin and that have less to no shadows and highlights information . A good technique to use is
the cross-polarization photography, that removes the specular highlights when shooting
textures.
In order to get as close as possible to the skin structure I used the displacement scans provided
by TexturingXYZ as they contain 3 levels of skin details which provide more than enough for
getting a wide range of details on the skin.
The cross polarized pictures and scans that I ended up using are provided by Eisko.
Texturing (2:00) :
I started the texturing process by projecting the diffuse and displacement map.I also used
noises on the top of these maps so the skin projections don’t look flat and provide interesting
variations.
These two maps were probably the ones that required the most patience as they dictate how all
the other maps will look like.
We need to take into consideration that the projected textures reflect a combination of skin
layers so we need to split the color maps in the three layers of the skin : epidermis (shallow
map), dermis (mid map) and subcutaneous (deep map).
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Epidermis
The epidermis contains mainly dead and shed skin cells.
Taking into consideration that the dead skin cells lose their color properties,I started by
decreasing the saturation of the original painted texture and adjusting the contrast until I got a
pale skin tone. In order to keep the pore details visible from distance I overlayed the
displacement map created on the top of the shallow map.
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Dermis
The dermis contains blood vessels, nerve endings and hair follicles. I started implementing
these features by taking the diffuse map and increasing its saturation. The reason behind this is
the fact that the dermis is vascularised, and its color is more intense than the epidermis . I
painted with a purple tint the thin layer of skin under the eyes, sides of the nose and ears. This
feature is an artistic choice as blood is not purple but it looks like that in those areas because of
the way light is absorbed by skin and the optical illusion given by the contrast between the skin
layer and blood vessels inside the skin. I also added small veins around the nose and ears area
for getting some extra texture details.
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Subcutaneous Tissue
The subcutaneous tissue contains larger blood vessels, fat tissue and nerves. In order to
reproduce its appearance I used a few hue and saturation shifts on the top of the diffuse map so
it looks like a red skin surface. This layer will be the one providing the SSS details in the thin
parts of the body like the ears or nose.
The other maps like roughness and specular maps were created based on the color maps. I
turned them to grayscale and balanced the contrast necessary for each of them.
There were also utility maps like convexity, concavity and deep mask that I created by baking
the high poly scan. I used those for multiple purposes like making the pores more visible on the
textures or controlling the SSS effect.
Lighting and Shading (1:30):
I started with a flat lighting in order to make sure that every part of the head looks right. After
that I did a lot of tests with different lighting models used by portrait photographers. Finally, I
decided that I will use a “butterfly” lighting setup which is quite popular for defining the shape of
the model and making it feel more cinematic.
The shading process was by far my favorite part of this project. The challenging part during the
shading process was finding a good balance between the skin layers in the SSS slots. The
reason behind this is the fact that in order to get realistic results, the sub surface scattering
effect should be visible but not too intense. However, if the maps are properly done, the
problems during the shading process are minimal. Overall the shading was all about tweaking
different textures, creating layered shaders and getting the correct balance between the maps.
Conclusions(00:30):
I am really happy with the results I have got and I will continue to improve my look development
knowledge.The weak point of my project would be the fact that I didn’t manage to implement too
many skin imperfections which would have helped me a lot for providing better realism. I also
think that I could be more organised and that this also influenced a bit the final result.
I learned a lot about skin and SSS materials in general, I improved my knowledge in the
texturing and lighting field and I managed to understand the importance of researching before
jumping into 3D which may be one of the most important achievements that i earned during this
project.