Over the next few weeks, guest columnist Anders Lejczak [bazze]
shares his Cinema 4D expertise with the Renderosity community.
Anders combines his passion for airplanes and his talent as a CG
Modeler to bring you this outstanding tutorial series: Modeling,
Texturing and Rigging a Republic P47. This week, Part 4:
UV-Mapping and Texturing!
Who is this for? This page will probably be most useful for
those who have tried & failed using body paint (or never used it) -
not for those already using it. I have received a comment telling
me to "instead of building plastic toy planes" should "model and
texture each panel individually". Have that in mind before blindly
following everything I have written :) Tools you need: An editor
that handles layers (Photoshop, TheGimp or alike) and a UV-mapper -
BodyPaint. Creating the base for the UV-template. Fire up
your 2D editor and create a new 2048*2048 document. Fill it with
white and save it as "uv-template.jpg". Create a new material in
C4D and apply the "uv-template.jpg" in the color channel. Apply
this material to _all_ objects (not to lights and environmental
objects if you have any). Preparing the mesh Before I plunge
into UV-editing the mesh I will fix a couple of small things that
will make the UV-editing easier. I have connected all objects that
don't need to be individual objects (for example the fuselage with
the fuselage details). I have also connected the wings with all the
flaps and ailerons. Why? Because it is _much_ easier to separate
these object again later than UV-edit all these objects separately.
Consequently I have connected the tail wing with the pitch.
Setting selection tags The selection tags are a must. Why?
Because they will help you select specific polys or areas of polys
while you UV-edit your mesh. Set selection tag on areas that will
need special attention or are difficult to select. I have selection
tags on the following objects:
- Fuselage (a tag for all left side polys, a tag for all right
side polys and a tag for the inside if the cowling).
- Wings (a tag for the top side and a tag for the bottom
side)
- Tail wings (a tag for the top side and a tag for the bottom
side)
- Instrument panel (a tag for the dashboard polys)
- Rudder (selection tags for the left & right side polygons) This
is how you set a selection tag (on the fuselage for example):
- Select all polys on the left side using the usual selection
tools.
- From the select menu choose "set selection" (a red triangle
appears next to the fuselage object). Name your selection
"leftbody"
- Invert your selection (now all polys on the fuselages right
side should be selected)
- BEFORE you create another selection tag make sure that you
deselect the previous one - otherwise it will be overwritten with
the new selection. I do this irritating mistake all the time.
Deselect the "leftbody" tag by clicking on the fuselage object in
the object hierarchy. The polys on the right side of the fuselage
should still be selected - now set another selection tag (a second
triangle should appear next to your fuselage object) and name it
"rightbody". UV-editing Now to the actual UV-editing! Switch
to UV-Edit mode (by selecting this option from the layout
menu).
Our approach will be to begin with the large object and continue
with the smaller. Let's UV-edit the fuselage.
- right click on the texture/material (the blank white one we
created) and select load texture (the texture now also appears in
the top right 2D view, i.e it turns white)
- set the brush size to 2
- set the brush color black
- select _all_ polygons on the fuselage The above picture looks
like a mess but don't worry.
- click on "start interactive mapping"
- use the rotate/scale tools to well.. scale and rotate the UV
until it looks like in this picture.
- Click on "stop interactive mapping"
- Don't deselect!
- Click on the "Use UV-polygon Edit Tool" (if you are not sure
which this is then move your pointer over the different tools -
their names pop up in the lower left side of your screen).
- Select "Outline Polygons" from the "Layer" menu (this carbon
copies the polygons onto your texture)
- Double click on the selection tag "bodyright"
- Click on the "Move tool" and move the selected polys up into
position as shown in this image.
- Select "Outline Polygons" from the "Layer" menu.
- Tadaa.. you now have UV-mapped the fuselage into one left and
one right side
Proceed in exactly the same way when UV-editing the wing. Keep in
mind that you need the reserve space for all other objects as well.
Don't forget your selection tags (for example the dashboard). When
you have gone through all your objects you should have a UV-map
similar to this. Save and the UV-map will replace the blank white
texture you created at start. Question from visitor: When I use
BodyPaint I always UV-edit and texture the low-poly cage while it's
still in a HN and I noticed that you don't - why not? Answer:
Hmmm... I have never thought of doing it in that way. Probably
because I (still) see modeling and UV-editing as 2 separate steps.
More experienced users maybe integrate modeling and UV-editing more
than I do in the work process. I see your point though and will try
that approach next time. However - before I start UV-editing I like
to connect as many objects as possible. I have for example
connected the fuselage with the cowling and a number of fuselage
details. In this way I will only need to UV-edit one object (The
Fuselage) instead of say 5-7. This makes the UV-editing a lot
easier but I cannot connect objects if they are a mix of
hypernurbs, primitives and editable meshes. Question: I see
that you don't use the BodyPaint Relax function, any specific
reasons for this? Answer Well lack of experience from using
the feature is the main reason :) The "stretch-effect" (around the
seams) is almost non-existent in this model even though I haven't
relaxed the UV. I can also minimize the risk of distortion by
compensating for it when I paint the texture. If I would texture a
more spherical and complex object, a head for example, then I
definitely would need to relax the UV.
Texturing Tools needed: An editor that handles layers
(Photoshop, TheGimp or alike). Warning: You will probably
end up with a 40-50 Mb psd file (if you're using Photoshop). If you
plan running Photoshop and C4D simultaneously then I would
recommend that you have 1 GB RAM in your computer. I'll be creating
a single 2048*2048 texture that will be used on the entire model.
The shader settings will however be different on different objects
because they're made of different materials. We'll begin with
creating a bump map (this can also be used in the diffusion and
specular color channels). Creating a map like this is easy - create
a new layer with your UV-map (the one created in the previous
step). Now create a new layer with drawing we used in the reference
setup on top of the UV-layer. You will probably have to scale &
stretch it a bit to fit the UV-map. Create new blank layer on top -
name it "bump" for example. Make both the bump layer and drawing
layer transparent (lower the layer opacity) so that you can make
out the UV-map. The reference drawing has all the panel lines (and
rivets) so you can easily see where to paint your bump (in the bump
layer). I use a 2048*2048 canvas and a 2 pix black brush (not
pencil) to draw the lines. Save as "bump.jpg". Basic color
layer This is also easy - just paint green where it should be
green, grey where it should be grey and blue where it should be
pink etc (hehe just kidding - blue where it should be blue). Don't
worry about details yet - just get the color areas right. Search
the web for reference photos, or even better illustrations.
3D enhancing layer 1 Even though we're texturing a 3D object
we still need a trick or two to enhance the 3D feeling. Light your
bump layer and make a copy if it and place it _under_ the original
bump layer. Blur it a bit using Gaussian blur and name it "bump
blur". Make another copy of the original bump layer and place it on
the top. Name it "bump light" , invert it (the lines should be
white now) and move it 1-2 pixels to the right and then 1-2 pixels
to the top.
Details layer. Add markings, texts, gradients and other
texture details in this layer.
Dirt layer Use a big soft low opacity brush to paint the
dirt. It's likely to be dirty around exhaust, engines, guns, edges
of moving parts etc. Damage layer The aircrafts paint is
most probably more or less damaged / worn. Select a soft low
opacity brush and paint on the borders of the objects that you wish
to make look worn or weathered. Use light grey or a lighter color
of the one you are currently painting over.
Paint is likely to chip of around rivets, panel edges, maybe around
the cockpit and other exposed area. I have painted these jaggy
shapes in such areas. I made the basic color layer a bit
transparent so that I can see where the edges are. You can combine
the bump & damage layer if you wish to enhance the damage in the
render and use the combination in your bump, diffusion or specular
color channels.
3D enhancing layer 2 Enhance the 3D-feeling by adding
shadows between plates and between parts that move (for example
flaps). The easiest way is to use some kind of drop shadow
function/plugin for this.
Structure layer You can get rid of the polished look by
creating a new layer and fill it with a dark brownish color.
Add a lot of noise and turn up the contrast - play around. Set the
layer to screen mode and lower the opacity. I personally think that
this step adds structure to the textures makes the texture look
more realistic once applied.
Above image is a test render. Next Week: Poserizing and rigging the
model in Poser.
We invite you to visit:
All supporting images within this article are
copyright,
and cannot be copied, printed, or reproduced in any manner without
written permission from the artist
 We would like to thank guest columnist Anders
Lejczak [bazze] for this outstanding tutorial series. Anders
has been a member of Renderosity for over 6 years. As a Cinema 4D
artist his Renderosity Art Gallery combines his passion for
airplanes and his talent as a CG Modeler. February
13, 2006 |
Comments