Byron Kindig presented UV Mapping to the attendees of the Blender Conference.
You can download a
ZIP Archive of the files from the
presentation if desired.
In this demo today we will be learning one way to create a UV Texture
map for a simple character. This will work for other objects such as
buildings as well.
Need Mesh
First
we will need a mesh to place our UV map onto. We will use a simple
and not so sophisticated character mesh, I call Ugly Bob.
(UglyBob.blend) We will be opening the mesh up so that it will lie
flat. In order to do this we will need to mark some seams so that we
can “cut” the mesh. We want these seems to be in places where
they will not show as much. We well put as many as we can at borders
of clothing to help hide the seams.
Marking
Seams
Make
sure the mesh is selected in object mode and then Tab into edit mode.
Once we have decided where we want to cut our mesh, we need to
select those edges. This is of course best done in Edge Select mode.
Once the edges are selected, press Ctrl E Key and select “Mark
Seams.” When an edge is marked as a seam, it will turn orange, to
make it easier to find. We don’t need to do them all at once. We
can add edges to our seams, as well as remove edges. If we have
marked seams and then change our mind we can reselect the edges and
with the Ctrl E Key again, choose “Clear Seams.”
(UglyBobSeams.blend)
Unwrapping
our Mesh
Before
we unwrap our mesh, we need to select all the faces in Edit Mode.
This can be done with the A Key. If you want to only place a UV Map
on some faces, select only the faces you want to place an image on
with any of the usual face select techniques.
Make
one of the windows on your screen into a UV Editor window if you have
not already done so. The UV Editor window has a grey grid, with its
own cursor. It looks similar to the 3D cursor, but is a diamond
shape instead of a circular shape. Remember, the UV cursor is a 2D
cursor instead of a 3D cursor, because a UV image is a 2 dimensional
image that is mapped on the surface of a 3 dimensional shape.
With
your mouse pointer in the 3D view window press the U Key and choose
"Unwrap". The UV Editor window will show your UV layout. It looks
like a bunch of vertices with dashed lines connecting them. Do not
be fooled. They are not really vertices! They are called nodes, and
there are more of them than there are vertices in the mesh. Where
ever their was a seam cut, there is node on each side of the cut for
every vertex.
The
good news is that although they are not vertices, they can be
selected, moved, rotated, and scaled, the same way that vertices are
moved, rotated, and scaled. If you want to move a node, select it
and press the G Key. If you want to constrain it to the left and
right axis press the G Key, then the X Key. If you want to constrain
the movement to the up and down axis, however, press the G Key
followed by the Y Key. Again it is a two dimensional image, so there
are only 2 axis, X and Y, but not a third or Z axis.
Rearranging
our layout
Sometimes
the layout has islands that overlap. We can select one node from an
island by right clicking on it. We can then press the L Key to
select all the connected vertices. Once the entire island is
selected it can be scaled, rotated, or moved to a new location where
it does not have to share space with other islands, and therefore
have its own texture and color.
(UglyBobRearange.blend)
Pinning
and Live Unwrap Transform
Sometimes
we want to change the UV lay out so that faces that need more detail
are larger and faces that don't require so much detail are smaller.
If you look at the nodes that represent our character's face,
(highlighted in the image above,) for example, you will see that the
area that we want the most detail has the smallest area on our UV
layout. We can use Pinning and Live Unwrap Transform, to stretch
this area into an easier layout to work with. You can think of the
pinned nodes as handles with which to stretch the layout.
First
click on the UVs in the UV Editor window's footer and select Live
Unwrap Transform, from the menu. Now select one or more nodes in the
layout and press the P Key to set it as a pinned node. You will know
it is pinned because it will be highlighted in red. You can Unpin a
node by selecting a pinned node and pressing the Alt P Key.
Now
if you select a pinned node or group of pinned nodes, and move,
scale, or rotate them, they will stretch the island that they are
part of.
(UglyBobPinned.blend)
As
you can see, the area of the character's face is a lot larger and
relatively easier to see when we start to create a texture for it.
You
can select all the pinned nodes by pressing Shift P Key
Save UV
unwrap
Once
you save your UV Unwrap you can not change the locations of the nodes
or your image will be out of registration, so be sure it is as you
want it before this step.
Change the
window on the left to a scripts window and open the Scripts menu and
choose, "UV", then "Save UV Face Layout". By default, the
image will be saved as a Targa file. Name it and save it to a
location, where you can locate it easily. It will come in handy in
the near future.
Creating
UV Texture Image
In the
footer of the UV Editor window, click on Image then New.
In the pop
up window click on the color picker window and choose a base color
for your texture image. It will be Black by default, but I like to
make it the color of the skin of my character. Also name the image
and choose the width and height dimensions of the UV map image. If
you will be using this in a game, remember to keep these dimensions
both square (Width = Height,) and also equal to a power of 2,(256,
512, 1024, etc.) The smaller the image, the faster the rendering,
which is especially important for games.
When you
are done, click the OK button. Your UV image will suddenly be too
large for the window, so go ahead and press the Home Key to bring it
down to size. Remember, the UV Layout image and the UV Texture image
are not the same.
You can
now change the window on the left back to a 3D View port window.
Change the Viewport Shading to Solid, and the Mode to Texture paint.
This way you will be able to see your texture in real time, (although
right now it is just a solid color.) The buttons window will now
have a Paint panel with controls for your brush and a color picker.
The Tab
key will now toggle between Edit and Texture Paint mode. When in edit
mode you will be able to see the UV layout superimposed on the UV
image in the UV Editor window. In Edit Mode you will also be able
also to paint onto the UV image with your left mouse button or pen
tablet if you have one. Remember you can change options in the Paint
panel in the buttons window. Use the color picker to choose a color.
Use the sliders to control the Opacity, Size, Fall Off, and Spacing
of your brush. Click the little "p" at the other end of the
sliders to allow the pen pressure to control this parameter if you
are planning to use the pen tablet. Be sure the Draw button is
selected to be able to paint. You can Soften or Smear the colors with
the other two buttons, but they will not color anything.
In the
footer of the UV Editor window, scroll over (Middle Mouse button,
click and drag,)to the Edit button with the pencil icon and click it,
to be able to edit the UV image that is now only a solid color. Now
scroll back to the left and click on View and then Paint tools. This
will open a floating panel with the paint tools in the UV Editor
window.
In Texture
Paint mode ( Remember, Tab toggles between Edit and Texture Paint
modes,) you can paint directly on the mesh in the 3D View port window
and it will be copied onto the UV image. My preference is to start
by painting a little on each of the parts of the mesh as a way to
identify which islands in the UV image belong to which parts of the
mesh. They are often so distorted that I am not sure, otherwise.
Then I like to go back to the UV Editor window, Tab into Edit mode
and finish painting directly on the UV image.
Before
closing Blender be sure and save the UV image changes, by going to
the footer of the UV Editor window and clicking on "Image", then
"Save", or "Save As".
(UglyBobColor.jpg)
Importing
UV Layout in another program
Although
you can do a lot with the paint tools in Blender, it tends to be
slower and has fewer options than some other 2D graphics programs.
You may want to use another program such as The Gimp, or Photoshop,
to refine your UV images. To do this open both the UV image
(UglyBobColor.jpg) and the UV Layout targa
files,(UglyBobUVlayout.tga) in your 2D graphical editing program.
Select the layer in the UV image and duplicate the background layer.
Add another layer on top of that. Go to the UV Layout image and
select it, copy it, and past it on the blank layer of the UV image.
Change the blending type of the layer of the UV Layout copy to
Multiply. That will allow you to see what is underneath.
Editing
and saving Texture map
If you
have a photo of a texture you want to apply to the skin of your
character, open the texture image in the 2 D program and use the
clone tool to paint it onto the UV Image.
When you
are done, turn off the UV Layout layer and save the image.
(UglyBobColorPhotoTex.jpg) You will need to reload your UV image when
you return to Blender.
In order
for the UV Texture to Render you must add a new material to your
mesh. You then need to add a texture and make it an image type. You
can then use the UV image that you have created from the menu as it
is already loaded. In the material setting under the Map Input panel
change from Orco (Original Coordinates,) to UV. In the Map To panel
the default should already be set to Col for color.
One
material, Several Texture types.
You can
add other textures as well, such as for Nor (Normal) and assigning a
grey scale image to it to paint in wrinkles or warts onto your
character. This is much easier to do in the 2D program where you can
keep color on one layer and bump or normal on another layer. You can
make one layer semi transparent in these programs to align the bumps
with the color variations. Be sure to save the individual layers to
their own image files. Remember you can adjust the amount of effect
the normal map has in the Map To panel with the Nor slider.
There are
lots of other tutorials on this subject that you can find if you
search the web. I hope this one was helpful, but if it is not clear,
don't give up. Just look for another tutorial.
