UV Mapping in Blender: From Seams to Bake in Six Steps, in Order
Unwrapping almost never fails on its own. It fails on the seams you placed before and on the texel density nobody checked after. These are the six steps of UV mapping in Blender 5.2 LTS, in the order things actually break.
Before You Unwrap: Workspace, Islands and the Seam Rule
A UV map is how you flatten a cardboard box to stick a decal on it. Cut where you shouldn't and the decal wrinkles no matter how carefully you place it; make one face twice the size of another and the decal looks blurry on one and sharp on the other. Everything else follows from those two facts.
What a UV Island Is and Why It Breaks
An island is a continuous piece of surface that ended up flat after cutting. It breaks for two different reasons and they should not be confused: either the seam is in the wrong place, in which case no algorithm will save it, or the projection picked the wrong method for that shape. The symptom is identical, the texture stretches, which is why half of all tutorials have people dragging vertices that were never going to line up.
Sync Selection and Island Mode
Open the UV Editing workspace: the screen splits between the 3D viewport and the UV Editor. In the UV Editor, turn Sync Selection on only if you plan to select islands from the editor itself; to work in parts it is better left off and select in the viewport, because then you always know which faces of the model you are touching. In the viewport, enter Edit Mode and set the selection mode to Island: moving whole islands without breaking them apart is the difference between adjusting and wrecking.
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Step 1: Mark Seams With a Reason
There is no shortcut here and it decides the outcome. A seam is a cut line: wherever you put it, a discontinuity in the texture goes there.
Where to Cut: Silhouette, Joints and Hidden Faces
The rule has two halves: cut where the eye doesn't look and where the shape changes direction. On a character that means the rear centre line, the inside of the arms, the soles of the feet, behind the ears and the hairline. On a hard-surface piece it means every sharp 90-degree edge. If in doubt, ask where that cut would sit on a piece of clothing: that is where nobody will notice it in the render.
Mark Seam, Clear Seam and Seams from Islands
In the viewport, with edges selected, Ctrl+E opens the edge menu and Mark Seam lives there. With the same selection, Clear Seam undoes it. The tool almost nobody uses is Seams from Islands: it creates seams along the borders of islands that already exist, which is how you rebuild someone else's UV work or recover a map that got split with no documentation. Before moving on, check there are no stray seams across a flat surface: that is guaranteed shearing and it cannot be fixed later.
Step 2: Pick the Unwrap Method
With seams in place, select everything and press U to open UV > Unwrap. What you pick there matters more than any manual tweak afterwards.
Angle Based, Conformal and Minimum Stretch (SLIM)
Angle Based uses angle-based flattening and gives the best 2D representation on organic surfaces: it is the default and a solid starting point. Conformal uses least-squares conformal mapping, less accurate but more stable on simple objects, which makes it a good fit for small mechanical pieces. Minimum Stretch is the newest of the three: it reduces area and angle distortion at once, it is iterative, and it is usually the best start for characters. If you come from other software, it is the closest thing to an unwrap that just comes out right.
The Options That Actually Change the Result
The last-operation panel has four checkboxes worth more than the method itself. Fill Holes fills mesh holes before unwrapping, to avoid overlaps on meshes that are not closed. Use Subdivision Surface unwraps the subdivided mesh rather than the base one, essential if you will render with subdivisions on. Correct Aspect fixes non-square textures, but only works if the mesh has a material with an Image Texture node and that node is selected in the Shader Editor. And in Minimum Stretch: Iterations, where more iterations mean less distortion and more time; No Flip, which prevents faces from flipping; and Importance Weights, which lets a vertex group decide which areas get more room in the map.
Fast Projections: Smart UV Project and Friends
Smart UV Project cuts along angles and projects each group of faces along its average normal: it is the honest shortcut for mechanical and architectural work, tuned with Angle Limit, where a low value creates many islands with little distortion and a high value creates few islands with more distortion. Cube, Cylinder and Sphere Projection are for shapes that really are those shapes. Project from View is the decal tool and the flat-panel tool, and it can be run piece by piece. Lightmap Pack is not for hand texturing: it distorts on purpose because its job is spreading baked light.
Step 3: Measure Distortion Before Moving On
This is the quality check people skip and pay for in the render. Distortion is not guessed, it is looked at.
The Stretch Overlay
The UV Editor overlays include a stretch display that colours islands by how much their area or angles deform relative to the 3D model. Red marks where the texture is compressed or pulled. Walk the model with that on before touching anything: if a whole island is red, the problem isn't the unwrap, it's where you cut.
Minimize Stretch, Pins and Live Unwrap
For surgical fixes there is UV > Minimize Stretch, which redistributes the island without moving borders you have pinned: P to pin and Alt+P to unpin. With Live Unwrap on you see the result while you drag a pin, which saves dozens of passes. The practical rule: if an island needs more than two passes of Minimize Stretch, the seam is wrong and you should go back to step 1. Pushing the operator harder only moves the problem around.
Step 4: Even Texel Density
The most common flaw in amateur models isn't a crooked island: it's a sharp face and a blurry torso on the same character.
Average Island Scale and Its Two Checkboxes
UV > Average Island Scale equalises the relative scale of every island, which is exactly what spreads detail evenly. It has two checkboxes: Non-Uniform, which scales the U and V axes separately to reduce average stretching, and Shear, which corrects shearing. Run it on islands that are already unwrapped and without stray pins blocking the adjustment.
How to Work Out Pixels per Meter
The math is simple: pixels per meter equals texture resolution divided by the object's real size. With a 2048-pixel map and a 2-metre piece, the target is 1024 pixels per meter; if that same piece shares a texture with a 20-centimetre object, that object needs the same density or it will look blurry. Blender ships no texel density meter: install Texel Density Checker from extensions.blender.org to read the value and apply it. It is worth having if you build assets for games or for the web, where the texture budget is fixed.
Step 5: Pack With Enough Margin
Packing is deciding how islands sit inside the texture square. Bad packing wastes resolution; packing without margin ruins the bake.
Pack Islands: Shape, Rotate and Margin
UV > Pack Islands scales, translates and rotates islands to fill the space. In Shape Method, Exact Shape (Concave) uses the island's full shape and gives the tightest fit at the cost of time, Boundary Shape (Convex) works from the outline and won't place islands inside holes, and Bounding Box is the fastest and the most wasteful. Leave Rotate on and pick a Rotation Method to taste: Any for maximum usage, Axis-aligned or Cardinal if you want islands aligned to the axes. In Margin Method, Fraction is the precise one: with a 1024 texture and a margin of 1/1024 you leave one pixel between islands, which is exactly what prevents bleeding during a bake. Turn on Merge Overlapping to catch overlaps and Lock Pinned Islands if some islands cannot move.
UDIMs When One Texture Isn't Enough
If the asset is large and a single texture can't give you the density you need, the workflow moves to UDIM: several tiled textures numbered 1001, 1002, 1003. In Pack Islands, Pack To lets you pack toward the active or the closest UDIM. This is the normal route on production characters and the reason to plan the map from the start: spreading islands across tiles later costs much more than designing for it.
Step 6: Export the Layout or Bake
A UV map ends up as a file or as a baked map, depending on what you plan to do with it.
Export UV Layout to Paint Elsewhere
UV > Export UV Layout saves an image with the islands drawn and their grid, which is your template for painting in Krita, Substance or Photoshop. Export at the final texture resolution: a 1024 template for a 4096 map will have you painting detail that doesn't fit.
Baking in Cycles and When It Pays Off
If the goal is a normal map, an ambient occlusion map or a curvature map, the path is Bake in Cycles with the Image Texture node selected in every material. Baking from high to low poly is the standard flow for games and for any asset that has to look good with few polygons. What resolution the project can afford is decided by the engine and the platform, not by taste: if you are targeting EEVEE or a game engine, read Cycles vs EEVEE in Blender 5.2 first and size the texture budget to what that engine will actually handle.
The Errors That Cost You an Afternoon
Almost every UV problem has a visible symptom in the render and a concrete cause in the editor. Here is the short list.
Symptom-to-Fix Table
- Visible seam in the render: the seam is open or badly placed. Remark it where the eye won't look.
- Shearing that won't go away: there is a seam across a flat surface. Minimize Stretch can't fix what the seam broke.
- The UV doesn't match the final shape: Subdivision Surface is on and you unwrapped with Use Subdivision Surface off.
- You can't select a whole island: Sync Selection got turned on by accident in the UV Editor.
- Manual tweaks keep resetting: you moved UVs with Live Unwrap on and the map re-unwrapped itself.
- Bleeding lines along island borders when baking: zero or too small a margin in Pack Islands.
- Text and normals inverted: an island ended up mirrored; check No Flip or unwrap that island again.
What to Check Before Calling the UV Done
Eight quick checks: no stray seams; no mirrored islands; distortion reviewed with the overlay on; even density across pieces of the same asset; enough margin for baking; islands inside the 0-1 range or correctly spread across UDIMs; the layout exported at final resolution; and the map tested on the model with a checker texture, which is the only way to see at a glance whether anything came out crooked.
Conclusion
A good UV map is boring: nobody notices it. The bad one always shows up, always at the worst moment, always in the render. Follow these six steps in order, seams, method, distortion, density, packing and export, and every decision gets validated before you move to the next one, which turns texturing from a lottery into a process. And if your material needs no images, you can skip all of it: procedural materials in Blender 5.2 use no UVs, and for assets built with Geometry Nodes it pays to settle the UV before scattering, not after.
