z-brush tut- by KrisMCosta [Archive]

3d_devil

27-11-2005, 01:14 PM

i was wanderin accross the zbrush forum n found this.... 
 
the link to the original page. 
http://209.132.69.82/picasso/tutorial.htm 
 
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Krishnamurti "Antropus" Costa 
A while back I created a new model using ZBrush as
part of an advertisement for Pixologic at Cinefex Magazine. My idea was
to create a digital Picasso, having some fun while he was painting with
ZBrush. As Picasso's likeness for a commercial piece is not allowed
(because of the copyrights) I changed the final model but kept the main
idea. Picasso's Portrait is now part of a personal project. I'll try to
explain my creation process for this model in this tutorial. I don't
think my techniques are something new, but can be useful and insightful
for you.

I hope you enjoy. 

 

Modeling: 
 
Click over the images below to download some videos showing the progress of this model (DivX codec required):

 <a href="http://209.132.69.82/picasso/images/modeling001.avi" target="_blank" target="_blank"><img src="http://209.132.69.82/picasso/images/video001.jpg" border="0" height="179" width="180" border="0"></a> <a href="http://209.132.69.82/picasso/images/modeling002.avi" target="_blank" target="_blank"><img src="http://209.132.69.82/picasso/images/video002.jpg" border="0" height="179" width="180" border="0"></a> <a href="http://209.132.69.82/picasso/images/modeling003.avi" target="_blank" target="_blank"><img src="http://209.132.69.82/picasso/images/video003.jpg" border="0" height="179" width="180" border="0"></a>

Click over the link below to download all the shaders and light setup:

<a href="http://209.132.69.82/picasso/images/skin_light.zip" target="_blank" target="_blank">skin_light.zip</a> 


 You will find that I started this model as a
caricature but then decided to change and make it realistic. In some
parts of the video you will see some drastic changes in the head shape
that I did after finding some better references of Picasso ;) 

For the modeling process I used some of the most
common ways to sculpt using ZBrush. I started this model with few
ZSpheres, converted it to mesh and started to move points to get the
initial form. After this I created some more loops to help with the
definition and flow of the form, then I started to subdivide the mesh
to add more and more details. If I needed to correct something I just
went back to the lower levels and used the smooth brush to "erase" any
problems then I went to the next level up and kept working in the same
way until I achieved the desired result. Doing things this way will
allow you fix problems in your mesh much faster and with greater
precision than trying to correct it at the highest levels. To avoid
issues like that is always best to add details slowly, trying to get
the most you can from each level of subdivision. 

For the wrinkles I used the most common technique:
Projection Master with DecoBrush. In this quick example you can see
some random lines I created using DecoBrush: 

<img src="http://209.132.69.82/picasso/images/wrinkles001.jpg" height="600" width="800" border="0"> 

Back to the 3D Edit mode I use Transform > Inflate
to fill the areas between these lines with some volume, using a
small-medium brush size. To make the edges softer I use Transform >
Smooth. I keep using both Inflat and Smooth until I get a result I am
satisfied with. Remember that the quality of the details depends of the
number of polygons of your mesh since we are working with sculpture,
not bump maps:

<img src="http://209.132.69.82/picasso/images/wrinkles002.jpg" height="600" width="800" border="0"> 

Textures:

For the texture painting I used SimpleBrush combined
with different alphas and Colorized Spray as stroke type. I started
with a neutral and very light skin tone and I added different tones
with a very light pressure (about 3-4 on RBG Intensity). I slowly added
different spots and colors like I was painting in transparent layers of
color. 

<img src="http://209.132.69.82/picasso/images/textures001.jpg" height="600" width="800" border="0">

Here you can check the texture without the correct shader and light yet:

<img src="http://209.132.69.82/picasso/images/textures002.jpg" height="600" width="800" border="0">

Skin Shaders:

For the skin shader I used Sokar's solution and
changed some parameters to try to improve even more on this already
amazing shader. This shader is based on ColorizerTrishader and works
pretty well in the skin simulation tones, faking some sort of
subsurface scattering appearance. If is your intention to mimic this
material for your own study using the screen shot below, please pay
attention into the diffuse curves . To make this
shader to work properly you need to set up very high values to the
diffuse curves on channels S2, S3 and S4. This will cause your model to
appear very ?self illuminated? in the view port but don't worry because
after you hit the render button everything will be fine ;) 

<img src="http://209.132.69.82/picasso/images/shaders004.jpg" height="940" width="695" border="0">

 

After you conclude the creation of the main skin
shader using the parameters above (or importing the skin shaders you
just downloaded from this page) you need to copy this shader to another
channels. To do so, just click over the material you just created and
click on ?CopyMat? button. Now click on the next material slot and
click on ?PasteMat?. Repeat this step for the next 4 slots. 

<img src="http://209.132.69.82/picasso/images/shaders002.jpg" height="600" width="800" border="0">

 Now that you have 5 identical materials you can start to adjust one by one, adding a little bit 
more of specular in the second one, even more in the third one, fourth
one, fifth one. Now you have a library with 5 similar materials
different just in the amount of specularity. 

<img src="http://209.132.69.82/picasso/images/shaders003.jpg" height="600" width="800" border="0">

Multiple Shaders (for specular variation):

Now you can start to paint different levels of
specularity to make your model more appealing. As you know our facial
skin has different levels of specularity. Areas such as nose and
forehead are naturally more specular. Areas such lips, eyelids and
internal part of the nostrils are naturally humid in different
proportions. Have this in mind in order to create your shaders with the
right amount of specularity for each of these different areas. 

Before starting, click on the first shader slot (or
the one with the material with less specularity). Load your model in
the viewport, click on Edit. Change the color to white in the picker
and go to the texture menu. Change the values for Width and Height to
3000 to have some good resolution. Click on ?New?. 

Click on ?Projection Master? (G on your keyboard) .
Choose ?Colors? and ?Shaded? (is up to you to use ?Double Sided? and
?Fade? options). Click on ?Drop Now? button. Click over the second
material slot (some material with more specularity than the basic one).
Choose ?SimpleBrush? under the Tool menu. Choose the alpha you like
more to simulate different levels of specularity for pores. Change the
stroke type to ?Colorized Spray? and change the flow value for
something very low like 0.01. Change the placement value to the maximum
(= 1). Change the brush size to something very small. Try 3 or 4. Now
you can start to paint more specularity in some areas as described
above. You will see the result in real time and using these settings we
will surely avoid the ?plastic look? because you are simulating
different specular levels and also the pores on the skin. Finishing
with the first specular level, click on ?Projection Master? again and
choose ?Pickup Now?. Rotate and positioning your model and repeat the
last step and before to start to paint, just choose another material. 

<img src="http://209.132.69.82/picasso/images/shaders001.jpg" height="600" width="800" border="0">

Eyes:

For the eye material I used the same skin shader
just tweaked to look similar to the ToyPlastic shader (very specular).
For the texture painting I used Projection Master mode for the main
texture painting. Back to the 3D mode I used the radial mirror on Y
axis to paint more details and also add some effects with another
brushes like BlurBrush and Smudge. 

<img src="http://209.132.69.82/picasso/images/eyes002.jpg" height="600" width="800" border="0">

Here you can see the final texture and the final
shader, based on the skin shader but much more specular to mimic the
ToyPlastic specular level. 

<img src="http://209.132.69.82/picasso/images/eyes.jpg" height="600" width="800" border="0">

Lighting:

My settings for the light are very simple and based
on Sokar's light. I used just one light with the settings in the next
image. This light gives a soft look to the image with some nice soft
shadows. 

<img src="http://209.132.69.82/picasso/images/render_light001.jpg" height="531" width="800" border="0">

Render:

Here is the result using this simple solution for lighting without any kind of adjustments or fine tuning...

<img src="http://209.132.69.82/picasso/images/render_light002.jpg" height="531" width="800" border="0">

... and here you can see some different results
after some adjustments using the built-in tools under the Render menu
for color, brightness and contrast in ZBrush:

<img src="http://209.132.69.82/picasso/images/render_light003.jpg" height="531" width="800" border="0">

 

Don't worry about the self illuminated look of your
model in the viewport. This is caused by the parameters in the skin
shader...

<img src="http://209.132.69.82/picasso/images/render001.jpg" height="657" width="800" border="0">

... because after you hit the render buttom everything looks nice again :) 

<img src="http://209.132.69.82/picasso/images/render002.jpg" height="657" width="800" border="0">

Final Touches:

Because ZBrush is an amazing hybrid solution where I
can work with 2.5D and 3D all in the same environment, I find the best

way to paint hair is using the DecoBrush. With this brush you can
achieve some nice effects because of the fluid way that you can paint
with it. To get the best results, the use of a good tablet with pen
pressure becomes essential. Before to start the hair painting I baked
the layers (ctrl+b) and started the long hair painting for the head,
beard, eyelashes and eyebrows. To do so I used DecoBrush, Brush 35,
DragRect Stroke, draw size = 0, focal shift = 0. You may find it a
little difficult to paint precisely using this brush at the beginning
but you will quickly understand how it works and will get your best
results after some training. 

<img src="http://209.132.69.82/picasso/images/hair001.jpg" height="600" width="800" border="0">

For the final image I used the same model but I had
to change Picasso's likeness to avoid problems with the Copyright since
this work was created as an advertisement for Pixologic (Cinefex
Magazine #100). Every new model was created using the same skin shader
as base, even for clothes, background etc. Using this shader and light
as base you can get a pretty decent soft look to any of your creations.
Just give it a try and I'm sure that you will enjoy the results.

<img src="http://209.132.69.82/picasso/images/final.jpg" height="716" width="800" border="0">

I hope this tutorial proves to be useful for you guys and thanks to Pixologic for this amazing piece of software! Cya.

Krishnamurti "Antropus" Costa 
CG Artist 
<a href="http://www.antropus.com/" target="_blank" target="_blank">http://www.antropus.com</a>
 

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