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Lightwave
Modeling
By Mathew
Duafala
Part
1 Part
2 Part
3 *Part
4
 Well,
After the last article you should have a pretty decent model.
Now, however, we need to add the textures to make it look photoreal.
There are many factors that determine whether or not a viewer
will accept your creature as valid or not. After all, it is
easy to make a black cat at night in a shadow, whereas a slow
motion close-up of the creature passing by the camera is a job
that requires the kind of talent at ILM.
If you’ve paid attention to
most television horror movies, the creatures are usually shot
at night or in the dark, and they are usually moving pretty
quickly whenever they manage to find their way into the light.
The reason is twofold. First since the viewer never gets that
good a look at the creature, their imaginations can run wild.
If you were to ask people coming out of a movie what the creature
looked like they would all probably give you a similar but differing
answer, and they would all be equally vivid in the persons memory.
Secondly, since the viewer can never dwell to long on the creature
itself they don’t have time to see the small imperfections
that would betray the creatures CG or Animatronic origins.
With that in mind let’s set
up the texturing for the creature. The first step is, since
LW won’t render MetaNurbs, we will need to make it into
polygons. We have two options for this, either Metaform or freezing
the spline cage. We will use Metaform since it usually give
equal results with fewer polygons and we can then set up the
creature with the MetaMation plugin when it comes time to make
it move. I’ve found that I usually only need to use a subdivision
level of 1 for a decent looking model however in this case I
had to use a subdivision of 2. Once that is done we need to
save the polygons. I chose to save them as head_F to signify
that they were "frozen". Load that object into a blank
scene in LW and save the scene as headsurface.lws . I usually
will have a scene for each major object's surfaces. This isn’t
a problem since the objects texturing attributes are saved with
the object not the scene. And since there is a scene with nothing
in it but the object I can move the camera to look at it without
anything getting in the way.
The next step is to go back into
modeler and switch to a side only view of the wireframe. Once
that is done, press the Print Screen key and that will make
a copy of the screen to the clipboard. Go into PhotoShop and
select File-new-OK. It should automatically set the image size
to what ever is in the clipboard. Paste the captured screen.
Use the crop tool to crop the picture to as close to showing
the only the wireframe as possible. Then make a new layer and
set it’s transparency to approximately 50%. Use the paint
can to make the background pure white. Then switch to the airbrush
tool and set the color to black. There should be a faint outline
of the wireframe in the background. Now you can paint the bump
map with the wireframe as a guide.
Fig 2
First off, I only painted the bump
map for the lips in the side view. There is a reason for this
that will become apparent shortly. Once you have something that
looks similar to fig 2. Save as a PhotoShop document with the
background deselected. Then make a new picture that is square.
On this picture we will make the main bump map that will define
the overall texture of the creatures skin. Use the airbrush
to make something similar to fig 3. It will be necessary to
make the second image tillable. To do this you need to go into
filter-other-offset. Select some value so that the seams meet
somewhere near the middle of the image. Then use the magic stamp
tool with a soft edged brush to cover the edges. Save that then
go into your LW scene. Load the two maps and go into the surfaces
panel. Select the skin texture and go into the bump map panel.
Use autosize with the default settings and then select the second
bump map that we made. Change the mapping to cubic and antialiasing
to 0.1. Repeat this process for the diffuse channel and the
specular channel. Since LW uses the white areas to define the
highest value we will need to change the image to Negative Image
(this option is just under the picture of the image when you
loaded it in. Set the diffuse and specular values to 50% and
‘high’ respectively. Don’t forget to turn on
smoothing.
The reason that we are loading
it into the diffuse and specular channels is really quite simple.
Since we are using a bump map to try to create the image of
the skin being uneven and, well "bumpy". All the areas
between the bumps would in the course of the creature‘s
day become filled with dirt and dust and other things that would
prevent the skin there from giving off as much light, and that
is what a diffuse map determines. Along those same lines of
thinking, the tops of all the ridges would be "harder"
and they would have more of a highlight to them, that is why
we added it to the specular channel.
Go back into layout and do a test
render. Depending on how large you made your image map you may
need to scale it down a bit. To do this go into the surfaces
and select each channel and click on the size button. This will
bring up a requester and then you can simply press the forward
arrow to un-highlight the number and type in a multiple (ie.
3.2m*5) and press enter.
Once you are happy with the main
texture it is time to add the lips and ear texture. To do this
repeat the same process as above except this time the use planer
mapping along the x axis, autosized and make sure to use the
same map as the alpha map also. This will ensure that the white
areas of the map don’t wash out the part of the skin we
have already mapped. Set the bump strength to 100% on the first
map and 400% on the second. Now if you do a test render your
creature should still look pretty plasticie. This is do to the
default lighting in LW. Go into the lights panel and turn the
diffuse lighting down to 0. Change the distant light in the
scene to a point light with an intensity of 50% and move it
to above the camera. Clone that light and move it to below the
camera and a little back. Now do another test render. It should
look much better now. Using the techniques that I outlined above
you should be able to go in and start fiddling with different
maps to achieve different effects.
Fig 3
Some of you may be wondering why
I didn’t use any scanned image maps on this creature. If
I had it would probably look a fair bit better, but I decided
that since not everyone has a scanner I would use the least
common denominator and just draw them from scratch. If you do
happen to have a scanner then by all means use it. Find some
children’s books at the local library, or in your kid’s
room depending on your situation, and scan in a photo of some
skin. Crop it to look as close to semetric as possible and then
use the technique I gave above for making it tillable. Once
you have that done then use the saturation tool to turn that
saturation down to zero. This should make the picture black
and white. After that use the brightness/contrast tool to turn
the contrast up for the bump maps and such. Map that texture
into the color channel with the accompanying maps in their respective
channels and see how it looks. I think that you will pleasantly
surprised at the results. The eyes on this creature are just
a scan of a crocodiles eye as it was coming out of the water.
The mouth is just a flat pink color with a slight vein procedural
in the diffuse channel. The teeth and horns are a light yellow/beige
with a small fractal bump map added. That pretty much sums it
up for this portion of the tutorial. Next time I will go into
how to set up a bone structure and IK.
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