UV Tools¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: Header ‣ UV
Hotkey: U

Blender offers several ways of mapping UVs. The simpler projection methods use formulas that map 3D space onto 2D space, by interpolating the position of points toward a point/axis/plane through a surface. The more advanced methods can be used with more complex models, and have more specific uses.

Unwrap¶

Reference

Editor: 3D Viewport and UV Editor
Mode: Edit Mode
Menu: UV ‣ Unwrap
Hotkey: U

Flattens the mesh surface by cutting along seams. Useful for organic shapes.

Begin by selecting all faces you want to unwrap. In the 3D Viewport, select UV ‣ Unwrap or U and select Unwrap. You can also do this from the UV Editor with UV ‣ Unwrap or U. This method will unwrap all faces and reset previous work. The UVs menu will appear in the UV Editor after unwrapping has been performed once.

../../../_images/modeling_meshes_editing_uv_unwrap-example.png

Result of unwrapping Suzanne.¶

This tool unwraps the faces of the object to provide the «best fit» scenario based on how the faces are connected and will fit within the image, and takes into account any seams within the selected faces. If possible, each selected face gets its own different area of the image and is not overlapping any other faces UVs. If all faces of an object are selected, then each face is mapped to a part of the image.

Options¶

Blender has two ways of calculating the unwrapping. They can be selected in the tool setting in the tool panel in the 3D Viewport.

Angle Based: This method gives a good 2D representation of a mesh.
Conformal: Uses LSCM (Least Squares Conformal Mapping). This usually gives a less accurate UV mapping than Angle Based, but works better for simpler objects.
Fill Holes: Activating Fill Holes will prevent overlapping from occurring and better represent any holes in the UV regions.
Correct Aspect: Map UVs taking image aspect into account.
Use Subdivision Surface Modifier: Map UVs taking vertex position after Subdivision Surface Modifier into account.
Margin: Space between UV islands.

Truco

A face’s UV image texture only has to use part of the image, not the whole image. Also, portions of the same image can be shared by multiple faces. A face can be mapped to less and less of the total image.

Smart UV Project¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Smart UV Project
Hotkey: U

Smart UV Project, cuts the mesh based on an angle threshold (angular changes in your mesh). This gives you fine control over how automatic seams are be created. It is good method for simple and complex geometric forms, such as mechanical objects or architecture.

This algorithm examines the shape of your object, the faces selected and their relation to one another, and creates a UV map based on this information and settings that you supply.

In the example below, the Smart Mapper mapped all of the faces of a cube to a neat arrangement of three sides on top, three sides on the bottom, for all six sides of the cube to fit squarely, just like the faces of the cube.

../../../_images/modeling_meshes_editing_uv_smart-project.png

Smart UV project on a cube.¶

For more complex mechanical objects, this tool can quickly and easily create a regular and straightforward UV layout for you.

Options¶

The Adjust Last Operation panel allows fine control over how the mesh is unwrapped:

Angle Limit: This controls how faces are grouped: a higher limit will lead to many small groups but less distortion, while a lower limit will create fewer groups at the expense of more distortion.
Island Margin: This controls how closely the UV islands are packed together. A higher number will add more space between islands.
Area Weight: Weight projection’s vector by faces with larger areas.

Lightmap Pack¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Lightmap Pack
Hotkey: U

Lightmap Pack takes each of a mesh’s faces, or selected faces, and packs them into the UV bounds. Lightmaps are used primarily in realtime rendering, where lighting information is baked onto texture maps, when it is needed to use as much UV space as possible. It can also work on several meshes at once. It has several options that appear in the Toolbar:

You can set the tool to map just Selected Faces or All Faces if working with a single mesh.

The Selected Mesh Object option works on multiple meshes. To use this, in Object Mode select several mesh objects, then go into Edit Mode and activate the tool.

Options¶

Share Tex Space

This is useful if mapping more than one mesh. It attempts to fit all of the objects” faces in the UV bounds without overlapping.

New UV Map

If mapping multiple meshes, this option creates a new UV map for each mesh. See UV Maps.

New Image

Assigns new images for every mesh, but only one if Shared Tex Space is enabled.

Image Size: Set the size of the new image.

Pack Quality

Pre-packing before the more complex Box packing.

Margin

This controls how closely the UV islands are packed together. A higher number will add more space between islands.

Follow Active Quads¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Follow Active Quads
Hotkey: U

The Follow Active Quads tool takes the selected faces and lays them out by following continuous face loops, even if the mesh face is irregularly-shaped. Note that it does not respect the image size, so you may have to scale them all down a bit to fit the image area.

Options¶

Edge Length Mode

Even: Space all UVs evenly.
Length: Todo.
Length Average: Average space UVs edge length of each loop.

Nota

Please note that it is the shape of the active quad in UV space that is being followed, not its shape in 3D space. To get a clean 90-degree unwrap make sure the active quad is a rectangle in UV space before using «Follow active quad».

Cube Projection¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Cube Projection
Hotkey: U

Cube Projection maps the mesh onto the faces of a cube, which is then unfolded. It projects the mesh onto six separate planes, creating six UV islands. In the UV editor, these will appear overlapped, but can be moved. See Editing UVs.

Options¶

Cube Size: Set the size of the cube to be projected onto.

Common¶

The following settings are common for the Cube, Cylinder, and Sphere mappings:

Correct Aspect: Map UVs will take the images aspect ratio into consideration. If an image has already been mapped to the Texture Space that is non-square, the projection will take this into account and distort the mapping to appear correct.
Clip to Bounds: Any UVs that lie outside the (0 to 1) range will be clipped to that range by being moved to the UV space border it is closest to.
Scale to Bounds: If the UV map is larger than the (0 to 1) range, the entire map will be scaled to fit inside.

Cylinder & Sphere Projection¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Sphere Projection UV ‣ Cylinder Projection
Hotkey: U

Cylindrical and Spherical mappings have the same options. The difference is that a cylindrical mapping projects the UVs on a plane toward the cylinder shape, while a spherical map takes into account the sphere’s curvature, and each latitude line becomes evenly spaced. Useful for spherical shapes, like eyes, planets, etc.

../../../_images/modeling_meshes_editing_uv_sphere-projection.png

Using an equirectangular image with a Sphere Projection.¶

Normally, to unwrap a cylinder (tube) as if you slit it lengthwise and folded it flat, Blender wants the view to be vertical, with the tube standing «up». Different views will project the tube onto the UV map differently, skewing the image if used. However, you can set the axis on which the calculation is done manually. This same idea works for the sphere mapping:

Recall the opening cartographer’s approaching to mapping the world? Well, you can achieve the same here when unwrapping a sphere from different points of view. Normally, to unwrap a sphere, view the sphere with the poles at the top and bottom. After unwrapping, Blender will give you an equirectangular projection; the point at the equator facing you will be in the middle of the image. A polar view will give a very different but common projection map. Using an equirectangular projection map of the earth as the UV image will give a good planet mapping onto the sphere.

Options¶

Direction

View on Poles: Use when viewing from the top (at a pole) by using an axis that is straight down from the view.
View on Equator: Use if view is looking at the equator, by using a vertical axis.
Align to Object: Uses the object’s transform to calculate the axis.

Align

Select which axis is up.

Polar ZX: Polar 0 is on the X axis.
Polar ZY: Polar 0 is on the Y axis.

Radius

The radius of the cylinder to use.

Project from View¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Project from View
Hotkey: U

Project from View takes the current view in the 3D Viewport and flattens the mesh as it appears. Use this option if you are using a picture of a real object as a UV Texture for an object that you have modeled. You will get stretching in areas where the model recedes away from you.

Options¶

Project from View (Bounds)¶

Reference

Editor: 3D View
Mode: Edit Mode
Menu: UV ‣ Project from View (Bounds)
Hotkey: U

Similar to Project from View, but with Scale to Bounds and Correct Aspect activated.

Reset¶

Reference

Editor: 3D Viewport and UV Editor
Mode: Edit Mode
Menu: UV ‣ Reset
Hotkey: U

Reset UVs maps each face to fill the UV grid, giving each face the same mapping.

If you want to use an image that is tileable, the surface will be covered in a smooth repetition of that image, with the image skewed to fit the shape of each individual face. Use this unwrapping option to reset the map and undo any unwrapping (go back to the start).