Editing UVs

After unwrap, you will likely need to arrange the UV maps into something that can be logically textured or painted. Your goals for editing are:

• Stitch some pieces (UV maps) back together.
• Minimize wasted space in the image.
• Enlarge the faces where you want more detail.
• Re-size/enlarge the faces that are stretched.
• Shrink the faces that are too grainy and have too much detail.

With a minimum of dead space, the most pixels can be dedicated to giving the maximum detail and fineness to the UV Texture. A UV face can be as small as a pixel (the little dots that make up an image) or as large as an entire image. You probably want to make some major adjustments first, and then tweak the layout.

Menu

Snap to pixel

Will force the UVs to snap to the nearest pixels of an image if loaded.

Constraining to Image Bounds

Turning on Constrain to Image Bounds will prevent UVs from being moved outside the 0 to 1 UV range.

Live Unwrap

Unwrap

Pin and Unpin

You can pin UVs so they do not move between multiple unwrap operations.

When Unwrapping a model it is sometimes useful to “Lock” certain UVs, so that parts of a UV layout stay the same shape, and/or in the same place.

Pinning is done selecting a UV, then by selecting Pin from the UVs menu, or the shortcut P. You can Unpin a UV with the shorctut Alt-P

Pinning is most effective when using the Unwrap method of UV mapping, for organic objects. An example is when you are modeling a symmetrical object using the Mirror Modifier. Some of the UVs on the mirror axis may be shared across the mirrored counterparts. You could pin the UVs that correspond to the midline, then align them on the X axis, and they will stay in that location.

Pinning also work great with the Live Unwrap tool. If you pin two or more UVs, with Live Unwrap on, dragging pinned UVs will interactively unwrap the model. This helps with fitting a UV island to a certain shape or region.

Pack Islands

Reference

Mode: View mode

Menu: UVs ‣ Pack Islands

Hotkey: Ctrl-P

The Pack Islands tool generates a optimized UV layout with non overlapping islands that tries to efficiently fill the texture space.

First it will uniformly scale the selected island, then individually transform each island so that they fill up the UV space as much as possible.

Average Island Scale

Reference

Mode: View mode

Menu: UVs ‣ Average Island Scale

Hotkey: Ctrl-A

Using the Average Island Scale tool, shortcut Ctrl-A, will scale each UV island so that they are all approximately the same scale.

Minimize Stretch

Reference

Mode: View mode

Menu: UVs ‣ Minimize Stretch

Hotkey: Ctrl-V

The Minimize Stretch tool, Ctrl-V, reduces UV stretch by minimizing angles. This essentially relaxes the UVs.

Stitch

Reference

Mode: View mode

Menu: UVs ‣ Stitch

Hotkey: V

Stitch, V, will join selected UVs that share vertices. You set the tool to limit stitching by distance in the Operator panel, by activating Use Limit and adjusting the Limit Distance

Seams

Mark Seam

Clear Seam

Seams From Island

Copy Mirrored UV coords

Transform

• Translate G
• Rotate R
• Scale S
• Shear Shift-Ctrl-Alt-S

Axis Locking

Transformations can be locked to an axis by pressing X or Y after one of the transform tools. Also, holding the MMB will constrain movement to the X or Y axis.

Mirror

UVs can be mirrored on the Y axis or the X axis:

• Mirror X
• Mirror Y

You can also use the hotkey Ctrl-M, then enter X or Y, or hold the MMB and drag in the mirror direction.

Snap

Snapping in UV/image editor is similar to Snapping in 3D. For the snap to pixel options to work an image has to be loaded.

Selected to Pixels

Moves selection to nearest pixel. See also Snap to pixel above.

Selected to Cursor

Moves selection to 2D cursor location.

Selected to Cursor (Offset)

Moves selection center to 2D cursor location, while preserving the offset of the vertices from the center.

Selected to Adjacent Unselected

Moves selection to adjacent unselected element.

Cursor to Pixels

Snaps the cursor to the nearest pixels.

Cursor to Selected

Moves the Cursor to the center of the selection.

Weld/Align

Reference

Mode: View mode

Menu: UVs ‣ Weld/Align

Hotkey: W

The Weld or Align tool, W.

Weld

The Weld tool will move selected UVs to their average position.

Remove Doubles UV

Straighten

Auto, X, Y

Align

Will line up the selected UVs on the X axis, Y axis, or automatically chosen axis.

Auto, X, Y

Proportional Editing

Proportional Editing is available in UV editing. The controls are the same as in the 3D View. See Proportional Editing in 3D for full reference.

Show/Hide Faces

• Reveal Hidden Alt-H
• Hide Select H
• Hide Unselect Shift-H

Export UV Layout

Using your favorite image painting program, you could use an exported UV layout to create a texture. Then save your changes, and back in Blender, use the Image ‣ Open menu entry to load it as your UV image for the mesh in Edit Mode for the desired (and active) UV map.

As a way of communicating to an artist who is painting your UV Texture for you, Blender has a tool called Save UV Face Layout (located in the UV/Image Editor, UVs ‣ Save UV Face Layout) that saves an image as a Targa (.tga), EPS, or an SVG format for the object you have selected.

The image is an outline of the UV face mapping. Activating the tool brings up the File Browser with options for saving the layout:

Export Options.

All UVs

if disabled, then only the UV faces selected will be outlined

Modified

Export UVs from the modified mesh.

Format

Select the type of image file to save (.png, .eps, .svg)

Size

select the size of the image in pixels. The image be square.

Fill Opacity

Set the opacity of the fill.

The image will be lines defining the UV edges that are within the image area of the UV mapping area. Edges outside the boundary, even if selected, will not be shown in the saved graphic.

The artist will use this as a transparent layer in their paint program as a guide when painting your texture. The example below shows Blender in the background, and the Gimp working on the texture, using the saved layout as a guide. Note that targa format supports the Alpha channel, so you can paint transparent areas of the mesh.

For using images as textures, see the page on Image Textures.

A UV Layout in the UV/Image Editor.

A UV Layout in an paint program.

Header

Pivot Point

The UV/Image editor has a 2D cursor. Its position can be changed by LMB clicking in the UV/Image editor. You can also manually adjust its position in the Properties region. The range by default is from 0 to 256 starting from the lower left corner. By enabling Normalized under Coordinates, the range changes from 0 to 1.

The Pivot Point can be changed to:

• Bounding Box Center
• Median Point
• 2D Cursor Location

Proportional Editing

Proportional Editing is available in UV editing. The controls are the same as in the 3D View. See Proportional Editing in 3D for full reference.

Snap

UV Data

3D View

Face Mirror and Rotate UVs

The orientation of the UV Texture is defined by each face. If the image is, for example, upside down or laying on its side, use the Face ‣ Rotate UVs (in the 3D View in Face Select mode) menu to rotate the UVs per face in 90-degree turns.

The Face ‣ Mirror UVs tool mirrors the UVs per face, which flips the image over, showing you the image reversed.