1. Computer Animation
UV Mapping

2. Why UV mapping
The procedural texture mapping is good for simple shaped objects
The image-object mapping is automatically calculated
Simple, but users have very limited control over which vertex is mapped to which point on the image
UV mapping is do-it-yourself texture mapping
Users can specify which vertex is mapping to which point on the image
Most characters in 3D games and movies are UV mapped

3. UV mapping The basic idea is to cut the 3D mesh model and “flatten it”
The flattened mesh is called a “UV map”, “UV texture”, or “UV layout”
You can superimpose the UV layout on an image and adjust the UV layout so that each vertex is mapped to the appropriate point on the image
Then you use the UV layout to guide the texture mapping

4. New in Blender 2.46+
The user’s manual and some old UV mapping tutorials refer to a “UV Face Select” mode
Since Blender version 2.46, the “UV Face Select” mode is merged into the “Edit” mode
When reading these documents, replace “UV Face Select” mode with “Edit” mode, and the rest should still apply

5. UV mapping process Step 1: create UV layout Split the window into two
Left: 3D view
Right: UV/Image editor
In the 3D view window, enter “Edit” mode
Select the faces you want to unwrap
Press U, and select “unwrap” (or other unwrapping methods)
You will see the flattened mesh appear in the UV/Image editor window

6. UV mapping process Step 2: adjust UV layout
In the “UV/Image” window, select “Image” and open an image
You may replace this image later
Adjust the UV layout to match the image
Can move individual vertex or face
Can rotate or scale the faces in UV layout
In the 3D view, change Draw Type to “Textured”
You can preview how the image is mapped to the object
But you are not able to render it yet.
To render the result, you need to add material

7. UV mapping process Go to “Editing” (F9) panel
Under “Mesh”, take a note of the name of the UV Texture
By default, it’s “UVTex”

8. UV mapping process Step 3: apply the UV layout in texture mapping
In 3D view, switch to Object mode
Select the object, and create a new material for it
Create a new texture channel
Add a texture image
Load the texture image you used for adjusting the UV layout

9. UV mapping process
Under “Map Input”, press “UV” button and type in the name of the UV layout (e.g. UVTex)
Render the scene and now you can see the result of UV mapping

10. UV unwrapping method Press U to open the “UV Calculation” menu
You can unwrap the mesh in different ways
(Standard) unwrap
Cube
Cylinder from view
Sphere from view
And some other unwrapping methods
For “Cylinder from view” and “Sphere from view”, the object’s axis should be perpendicular to the current line of sight
Usually you want to switch to the front view

11. Mark seam
You may mark seams on the 3D mesh model to tell Blender where to cut the mesh open
So the mesh is unwrapped the way you want
In Edit mode, select edges, press Ctrl + E, and select “Mark seam”
When you unwrap this mesh, Blender will cut along the seams

12. Different UV mapping for different faces
You may want to UV map different images to different faces (or face groups)
First, select and unwrap different faces independently
And adjust the UV layout for different faces independently
To apply the UV map, you need to assign different materials to different faces
See

13. Different UV mapping for different faces
Suppose you want UV map image A to a group of faces (group 1), and map image B to another group of faces (group 2)
In Edit mode, select face group 1, in Editing (F9) panel, under “Link and Materials”, create a new material and press “Assign” button to assign the material to group 1
In “Material Buttons” panel, you may give the new material a more meaningful name
Don’t forget to assign the new material to the faces

14. Different UV mapping for different faces
Create a new texture channel for the new material
Load image A as a texture
In “Map Input”, press “UV” button and type in the name of the UV layout

15. Different UV mapping for different faces
In Edit mode, select face group 2, in Editing (F9) panel, under “Link and Materials”, create a new material and press “Assign” button to assign the material to group 2
Create a new texture channel for the new material
Load image B as a texture
In “Map Input”, press “UV” button and type in the name of the UV layout

16. Export UV layout You can export your UV layout to an image file
In “UV/Image editor” window, select “UV”  Scripts  “Save UV Face Layout”.
You can open this UV layout image in Photoshop or GIMP to guide the creation or painting of your texture image
E.g. use the UV layout as a layer in Photoshop or GIMP to guide
Then you can use that image for texture mapping

17. Texture painting
You can paint directly on the image in “UV/Image Editor” window
You need to open an image first
Select Image  “Texture painting”
Press C to bring out the “Paint Tool” window
See for details

18. Pin
Sometimes you may want to keep part of the UV layout and “re-unwrap” the rest
You can pin certain vertices (or faces) in the UV layout so that they won’t be changed if you unwrap the mesh again
A useful feature if you want to progressively refine the UV layout

19. Pack image In “UV/Image editor” window, select Image  “Pack image”
The current image is packed into the Blender file.
The next time you open the “UV/Image editor” window, the image will be automatically loaded.
This is useful if you need to share the Blender file with someone else.