Cooking with colors
To follow this tutorial, you first need to create a scene in DAZ with a sphere and at least one panel, which serves as a source emitting light in Octane: I'm actually using three rear and two front panels, to add additional lighting later.
Since DAZ works with centimeters and Octane with meters, I have chosen to set the following parameters for the export and import dialogues. I understand, if no one corrects me, that these values are more appropriate than those in the manual:
The human skin consists of three layers: epidermis, dermis and hypodermis. The first two layers are very thin compared to the last layer, and give you skin a bluish hue. However, because most of the transmitted light they receive to the hypodermis, the end result is a reddish hue:
http://http.developer.nvidia.com/GPUGem ... _ch14.html
Chapter 14. Advanced Techniques for Realistic Real-Time Skin Rendering
In the next picture you can see the
scheme of the material that we will create. A
mix material, composed of a
diffuse material and a
specular material. The mixture will apply a 30% diffuse material and 70% to speculate (of course, everyone should try to find their own values with those that you are most comfortable):
First we apply
light to the scene by the panel that we have imported from DAZ. I'm not using ambient light and it is important to use for testing the rendering engine of
Path Tracing Kernel. In the next picture you can see: to the right, the values for the
emission; to the left, values for
Reflection and
Transmission Properties:
Why is the black dial? Or rather, why is not the sphere? The
colors we see in the objects are the result of subtracting from the light source, the colors absorbed by the objects. In our case we are using a white light source on an object, the sphere, which is absorbing all the light that hits it, and therefore does not reflect any color:
http://www.scratchapixel.com/lessons/3d ... teraction/
An Introduction to Light-Matter Interaction
We will then apply a color to the
Reflection property so that we can observe the light reflected by the object (try to also apply other colors):
Besides being absorbed and reflected light can be
transmitted through an object. In the following image we apply a color to the
Transmission property. Therefore, we can not only see the white light reflected on the field, but also the light transmitted by the object:
In fact, we can place ourselves in the back of the object, to see how light traversed it entirely up to the other side (as in the previous step, try to experiment with other colors and angles):
In the next step we will modify the
Roughness material property to obtain a less crystalline appearance (I have not changed the default
refractive index of the material):
Although, note that the light is transmitted from one end to the other object (as always my recommendation is you to try different values):
The transmitted light on an object can be
absorbed. The direct consequence of this is that the color of the object will change: if we absorb red, the hue of the object will approach cyan; if we absorb green, magenta; and if we absorb blue, yellow. For our material, we will absorb some red and green, for a more pinkish hue (try to absorb the primary colors):
The transmitted light on an object can also be
scattering into and out of it, as a result of deviations occurring in the light (refraction) when bouncing inside. If as a result of these boards, light back out through the surface of the object (although different from the input points), a translucent appearance occurs on the surface:
subsurface scattering:
http://www.youtube.com/watch?v=9T4ndSKeKWo
Subsurface Scattering by Juan Jimenez (in Spanish)
The following image shows the result after applying the scattering sphere. The
Phase parameter defines the type of scattering that are applying: inward (positive values); and outward (negative values) to obtain subsurface scattering. The
Scale parameter determines the amount of effect applied (although it is a value, the operation I will not just be entirely clear):
Note: when you apply scattering of a color (eg red), note that other colors are transmitted (green and blue). Therefore, the key of the object on the other end can vary unexpectedly (in our example toward cyan). While we could absorb some of these colors to lessen its effect.
To end our material we will apply some relief to his
Bump owned by employing
fractal generator Ridget:
In the next picture you can see
the final result at the top of the diffuse to which we are applying only one color material; at the bottom of the material specular, which is about to have done most of the settings; and finally, in the middle, the result of mixing in a proportion of 30% and 70% respectively:
It is time to apply our materials to our model:
Victoria 6:
Then we will use
image maps provided with the model, to apply them to the
Bump and
Transmission properties of our material. In the next picture you can see the scheme for nostrills, lips and face areas (surfaces from DAZ):
Note: It would be nice to group pins on Octane geometries, so that could unify the pin connections for those who share the same material.
The following image shows the
final result, after applying the textures:
I'm taking advantage of more panels in my scene, I'm going to play with the
lighting of the rear panels:
In the next picture you can see, as we did for the sphere, the
material behavior we have created:
Finally, to show the same image with
ambient light:
Since
ambient light uses a blue color and orange color to create the effect of natural light, the light received by our model differs from the
artificial light used until now.
This would be to revisit the parameters seen so far with this new light. For example, I leave here the last render, which I modified the following properties:
Absorption,
Scattering and
Roughness:
In sum, this is a process of testing and trials to get as far as possible, an acceptable result:
cooking with colors (or rather
with lights) ...
Regards
