UV UNWRAPPING AND PAINTING

Chakrit Watcharopas

Reference:The Essential Blender: The Official Guide to 3D Creation with the Blender Open Source Suite  Author Roland HessPublisher No Starch PressPublication Date 2007-09-27

UV unwrapping is a process of assigning a set of 2D coordinates to all object vertices

UV Unwrapping 2

Each XYZ vertex coordinate in 3D is mapped to UV coordinates in 2D

UV / Image Editor is a tool for this UV setting

Normally, we’ll bring up 3D View and UV / Image Editor side by side

UV Unwrapping (2) 3

To unwrap UV of object automatically, select the object, go to Edit Mode, and press U-key

There are a number of UV automatic calculation methods

The simplest ones are "Project from View" and "Project from View (Bounds)"

UV Calculation 4

"Project from View" and "Project from View (Bounds)" take the mesh exactly as seen in the current 3D view, and squash it right into the UV Editor

UV Unwrapping (2) 5

Project from View can be good when creating a texture that corresponds closely to the profile shape of the mesh

UV Unwrapping (3) 6

Options Cylinder, Cube, and Sphere are good for unwrapping objects that closely match those primitives in shape

Sometimes, there can be areas that don't map quite correctly or show distortion

"Unwrap" is the most useful; it uses a procedure called "Least Squares Conformal Map" (LSCM) in conjunction with seams marked in Edit mode to give excellent results with very little effort

UV Unwrapping (4) 7

Seams are added by selecting edges, pressing Ctrl-E and choosing "Mark Seam“

Marked seams appear as heavy orange edges

Seams can be unmarked by selecting those edges, pressing Ctrl-E and choosing "Clear Seam"

Seams8

In mesh Edit mode, hovering the mouse over an island of nodes in UV Editor and pressing the L-key will select the entire island

Realization: A single vertex from 3D mesh can have as many instances in the UV Editor as it has faces

Selecting Nodes in the UV Editor9

Icon Sync UV and Mesh Selection allows all vertices in UV Editor that share a 3D mesh vertex are selected if any of these vertices is once selected

Selecting Nodes in the UV Editor (2)10

Areas of unwrap that you are happy with can be frozen by "pinning"

Press P-key to pin selected vertices Blender uses all pinned nodes as a starting

point for the next attempt of unwrap If Live Unwrap Transform is enabled, there is

no need to re-unwrap your meshes after pins are adjusted

Turn off Live Unwrap so you don't accidentally move a pinned node and ruin your work

Pinning and Live Unwrap Transform11

Blender's Painting Tools can be used to paint onto existing images or to create new ones, and can be used either in the UV/Image Editor or to paint directly within the 3D view

To be able to texture paint a model in the 3D view, the model needs to be unwrapped

Paint Tools12