UV mapping in Blender bridges the gap between an unrendered 3D mesh and the texture that you eventually plan on enveloping it with later on. In this Blender walkthrough for beginners, we’re going to show you what UV maps are and how you can create one for any 3D model in Blender.
What Are UVs?
When you’re working with a 3D object, you’re working in 3D Cartesian space—a coordinate system with an X-axis, a Y-axis, and a Z-axis.
UVs are your way of translating the surface of a 3D object into 2D terms. Now, the field that you’re working with is flat. Instead of confusing it with an additional set of X and Y axes on the UV wrapper, we use a U-axis and a V-axis on a horizontal and vertical basis to differentiate the two.
There is a one-to-one ratio between every point on the UV map and every point on the surface of the 3D model. You can assign textures to your UV unwrap by face, by UV coordinates, or by brush.
To dig into Blender UV mapping officially, you’ll first need to do something very important: UV unwrapping; basically, peeling the skin off of the object’s surface. Brutal. Let’s begin.
How to Unwrap a UV Map in Blender
To unwrap an object’s UV mapping in Blender, there are a couple of things that we’ll need to do first. Here, we’re going to use this simple, six-sided box as an example.
First, we’ll need to mark a few Seams. Hit Tab to enter Edit Mode from Object Mode once you’ve got a model in front of you.
Once in Edit Mode, use the hotkey 2 to enter Edge Select mode. Now, you can select one of the edges of the box. Use the shortcut Ctrl + E to activate the Mark Seam tool once you’ve chosen an edge, cutting into the mesh.
You’ll be prompted by a long list of options. Select Mark Seam to mark your first seam.
Once you’ve done so, the seam should now be glowing red. Where should you mark the next one? You’ve got a couple of goals here: preventing the edges from lifting the mesh off of the 2D surface of the UV map, and keeping the mesh connected, at least for this simple practice exercise.
Many Blender artists liken this ritual to taking the foil off of a piece of chocolate or even simply just breaking down a cardboard box. This second example is highly analogous to our block friend. Our next two seams, naturally, should allow us to lift the top up on a hinge, ensuring that the entire thing stays connected.
Once that’s done, we can sort of visualize the edges preventing the box from lying flat. We’ve got two vertical edges on the X-axis still standing strong. Let’s mark these as seams connected to the “lid” that we’ve created on the bottom and continue on to the top.
More complicated meshes may offer things like Edge Loops that you can take advantage of, and you might even need to slice in a custom seam or two in order to find the exact UV map that you’re looking for.
In this case, our cube is looking pretty good. What do we need to do next?
At the top of your staging area, you should see a few categorized dropdown menus. Click into the UV dropdown; Unwrap is the first option, right at the top of the list.
Hit A to select your entire cube, and then use Unwrap up at the top—you should see a new window with more settings to adjust down in the bottom-right.
You can choose between Angle-Based or Conformal UV unwrapping protocol. What’s the difference?
An Angle-Based UV unwrap will yield the most accurate and faithful representation of your mesh possible. This option is the one you should be using for complicated meshes with a lot of detail to translate to the Blender UV map. Conformal texture mapping is governed by something called Least Squares Conformal Mapping, or LSCM. It’s a slightly more direct route to victory and works well for simple objects like this cube.
Other options include Fill Holes, Correct Aspect, and the ability to Use Subdivision Surface. These toggles can help you eliminate overlapping geometry, correct for your texture image’s aspect ratio, and give you more geometry with which to project your UV texture, respectively.
We’ve come a long way, but one fact remains: this box is still completely upright. How can we see this UV map in all of its two-dimensional glory?
Blender texture mapping takes place in the Blender UV Editor. You’ll find the UV Editing workspace alongside all of the rest, at the top of the Blender UI.
Hey, look at that—it really works. With your cube selected in its entirety, you should see a 2D projected view of its UV texture mapping.
Editing UV Maps in Blender
Once you’ve made it to this point, you’re able to adjust your UV mapping before assigning a texture and continuing to refine.
You’re free to use any of your normal operators in Blender to modify the character of your UV map. G, S, and R can be used to Grab, Scale, and Rotate any of the geometry that you’ve mapped to the UV here.
For more advanced models, you may find that isolating certain parts of the UV mesh is a helpful precaution to take when UV painting. Creating new edges and faces might also be helpful when texturing an object in Blender with precision.
Once you’ve finalized your UV layout, you’re ready to assign it a texture and to perfect your 3D model through texture painting and an entire world of procedural Texture Nodes.
These tools can be used to distort a texture image in order to make it look less “tiled,” as well as to break up an image with randomly-generated noise, which can be useful when designing things like cloud coverage or a decaying, ancient layer of stucco.
The possibilities are literally endless; this is to say nothing of all of the new Geometry Nodes at your fingertips, all brand new with Blender 3.0. There’s a lot to look forward to, especially if you’re just getting into 3D modeling now.
Do It Like the Pros
There are many ways to carry out a UV unwrapping in Blender. This simple approach gives you a lot of control over how it all pans out. Even though there are many automated tools at your disposal, sometimes, doing it the old fashioned way really is the best path forward.
