Part
2: Texturing and lighting the Nissan R390 GT in 3ds max 5
>> Section 3: Mapping and definition of UVW coordinates.
Mapping a model is a process to let 3ds max know which parts
of a bitmap are to be where on the model itself. In the simpler
situations, standard mapping options in 3ds max can be enough
(for objects similar to spheres, cylinders, cubes..), but,
as the model gets just a bit more complex, these methods are
no longer enough. A correct mapping has to achive 2 main objectives:
you must be able to paint simply and intuitively your textures
(Fig. 02) and it must not lead
to any distortions or arefacts in your renderings. Luckily
enugh, cars are generally built with big almost planar surfaces,
and this greatly simlpifies our task as we can almost always
use planar mappings and get good results with small tweaks.
Let’s see how we can map the Nissan’s bonnet:
at this stage we have objects with a modifier stack like this:
Editable poly > Simmetry > Meshsmooth. Let’s apply
a “Mesh select” modifier between the “Simmetry”
and “Meshsmooth” modifiers, go in “Polygon
selection” mode (by clicking on the little red square
in the modifier panel) and select the faces as shown in Fig.
03: as you can see, this selection can be mapped with
the same planar mapping (excluding the area inside the headlights,
but there will be just black paint so we can go on without
caring about this area). By doing this selection, we assured
that the next modifier in the stack will work only on the
selected polygons: let’s add (without deselecting the
polygons and leaving the small sqaure icon clicked!!!) an
UVWMap modifier, and select the “Planar” projection
option. Align and adjust the planar projection gizmo like
in Fig. 04, helping yourself
with the “fit” button and the alignment options
(in this case i aligned it to Y axis). Be sure to make the
gizmo square by changing the values to suitable ones (ie clicking
“fit” i got a 193x136 gizmo, which i rsized to
200x200). At this poitn, add a Unwrap UVW modifier to the
stack (always BEFORE the meshsmooth) and take a look at the
mapping so far achieved by clicking on “edit”
in the modifier panel (see Fig. 05).
Add a new Mesh Select modifier and select polygons again,
as in Fig. 6. Add another planar
UVWMap modifier as in Fig. 07,
making it square as before. Add another UnwrapUVW and check
the mapping (Fig. 08). To the
same for the left side of the bonnet (Fig.
09 and Fig. 10).
At this point add another Mesh Select modifier and DO NOT
select anything, so the next modifier will work on the whole
object. Add an UnwrapUVW modifier and click on “Edit”
to see how the whole surface has been mapped. As you can see
in Fig. 11, the 3 elements are
overlapping: this is easily fixed by selecting the scale,
rotate and move tools in the editng panel and checking the
“Select element” option. This way you can easily
accomodate the 3 elements in the square area as in Fig.
12.
As you can see, the selected element in Fig.
12 has to be mirrored (just click n th “Mirror”
icon) to get the proper mapping (Fig.
13). Also the main bonnet surface is somehow mirrored
(i realized this only after the first test render), so just
do the same operation on the main surface.
Sometimes (Fig. 15) having the
textures projected on the eding window is very usefull to
ad just particolar vertices and to check for distortions with
a visual feedback: to achieve this, yu have to click on the
“Show map” button and choose the exture you want
to see. If you cannot see anything on the background, chances
are that you simply need to push the “Brightness”
value in the “Show options...” panel to a value
greater than 0.
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