Intro to Unwrapping

WHAT ARE UVs?

What unwrapping is, what UV maps are, why they're important, how they're associated with texturing.

UVs are a 2D map of a 3D model’s surface. Just like you might flatten an orange peel to lay it out on a table, UV unwrapping takes a 3D object and lays its surface flat so textures know exactly where to go.

When a texture is applied, the software looks at the UVs to determine which part of the image appears on each part of the model. Without UVs, textures would stretch, smear, or appear in the wrong places. Good UVs ensure details line up correctly, edges stay clean, and patterns behave predictably.

A well-unwrapped model not only makes texturing easier but also improves performance. While alternative projection methods exist, they often sacrifice this performance and control, making UVs the industry standard. A skilled artist creates not only stunning art but also optimized assets. Think of unwrapping as a puzzle, one that becomes second nature with practice.

While this image may look funny, it’s a great visual representation of how UV unwrapping works in translating 3D to 2D!

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KEY TERMINOLOGY

Key terminology associated with unwrapping (e.g. seams, texel density, checker maps)

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UV SPACE

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Here you can see the packing box that we call UV space, with it’s axes and 0-1 points represented

UV space is the literal box that your UV’s have to fit in when creating a unique texture for your model. The name comes from the axis that it’s using: because X, Y and Z were already taken, we use U and V instead! The letters U and V simply represent the horizontal and vertical directions on a flat map, similar to X and Y on a graph.

The axes in the 2D space are named U and V to differentiate them from X, Y, and Z (used in the 3D space)! It’s also where the name UV comes from!

We refer to this space as the “UV Space” or occasionally the “0 - 1 Space” or “Packing Box”. This space goes from 0 (origin) to 1 in both of the bidimensional axes.

It’s important to note that not all scenario’s require the textures to be limited within this space, some textures like Trimsheets or Tileable textures often require you to go outside of it.

It’s important to mention that UVs tile infinitely:

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This is important, as it creates two different methods for texturing: using unique (object specific) textures, or a method called “tileable” or “trim” texturing. We’ll get into this more deeply, for now we’ll go over the principles that apply to both methods of texturing!

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UV ISLANDS

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UV Islands are the individual pieces that make up the 2D representation of our 3D model. To create these islands, we need to cut seams where the model will "unfold," allowing us to flatten it with as little distortion as possible.

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SEAMS

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Here’s an example of a barrel with seams used for unwrapping (marked in red in Blender). I kept the number of seams to a minimum while also aligning them with hard edges to prevent any baking issues.

Seams represent the cuts in our model that allow us to then unfold and flatten our islands. We create them by selecting edges/edge loops and marking them as seams within our modelling or unwrapping software.

KEEP SEAMS TO A MINIMUMFewer seams mean fewer visible breaks in the texture, as well as fewer UV islands to pack. This reduces wasted space between islands (since each island requires edge padding). Minimizing seams also help performance: every UV seam results in vertices being calculated twice along that edge, increasing the engine's processing load.

HIDE YOUR SEAMSSeams can create visible breaks in your textures, so it's best to place them in areas that won't be noticed. Try adding seams in less visible spots, like cavities or recessed areas, the bottom or back of your model, or parts of the mesh that are covered by other components. By strategically placing seams, you can avoid unwanted texture discontinuities and keep your model looking seamless and natural!

All hard edges must have seams, though seams don’t require hard edges.When creating a model that will have a baked normal map, if you have a hard edge in your model, you always should add a seam to it. If no seam is present on your hard edges, your baked bevels will have visual errors. However, it’s important to note that just because you place a seam doesn’t mean you have to harden the edge—seams work perfectly fine on smooth surfaces.

Take a moment to examine this model and think about where seams would make sense!

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UNFOLDING

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Here’s an example of different ways islands may be unfolded. While both methods can technically be used for texturing without visible distortion, the straightened version will produce a much cleaner result — free of artifacts along the edges — and will be far easier to pack efficiently due to its optimized shape.

If your seams are set up properly, unwrapping is mostly automatic in most 3D software. In Blender, once you’ve setup your seams we can then “Unwrap” our mesh. It will then try to do the best it can based on the seams we’ve created.

DIFFERENT UNWRAP MODESit's worth testing both Conformal and Angle-Based unwrap modes to see which works better for your model.

Depending on the shape of your model, different projection methods can help simplify the unwrapping process. Cylindrical, spherical, and cube projections work great for objects with matching forms, while planar projection—whether based on an axis or the camera view—is a solid choice for continuous surfaces.

Once seams are in place, we’ll have our UV islands. Some will be good to go right away, but others might need some adjustments to make them as clean and efficient as possible. So keep iterating to get the best results.

Relax and adjust islands by minimize distortion or remove any overlaps. This can be achieved by manually grabbing and dragging portions of the UV mesh, or playing around with unwrap settings.

Straighten islands when possible, especially along the outer edges and seams. Since textures are made of square pixels, keeping UVs straight helps avoid issues like aliasing or jagged transitions, making the final result much cleaner!

Most modelling software comes with built-in tools to handle unfolding and unwrapping, but there are also plenty of add-ons that can make the process easier and deliver even better results. If you’re using Blender, it’s worth looking into UV add-ons. You may also consider looking into RizomUV, a powerful software tool designed specifically for UV unwrapping. One step at a time, though — let’s keep focusing on the fundamentals for now.

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CHECKER MAPS

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Checker maps are placeholder textures that will help you double check if there is any distortion or stretching in your UV map. Check if everything is properly aligned, ensure consistent scale across details, and see if any seams are too visible.

Most 3D software includes a built-in checker map in their unwrapping tools, but you can always find custom ones online. Add-ons like TexTools also come with handy checker maps that you can apply with a single click.

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ISLAND ORIENTATION

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Aligning all wooden planks horizontally allows it to have a uniform direction in wood grain when texturing

Orientation of islands is important to minimize work later down the line and also to help with alignment to our pixel grid (remember that our textures used by our UV’s are a pixel representation). We’ve gone over why it’s important to align UV islands horizontally or vertically: to minimize artifacts caused by the square nature of pixels — but orienting the pieces correctly is just as vital!

The reason why orientation is handy, is when texturing we can align directional textures in one go. Take wood textures, for example — aligning all wooden pieces horizontally causes the pattern to naturally follow a consistent direction, making it look realistic. If your UVs aren’t aligned, you’ll be forced to create separate layers with different rotations for each piece, adding unnecessary work to an avoidable problem. Aligning similar pieces also helps keep texturing program file sizes down!

Some custom engine shaders also rely on UV direction! Rain effects that flow downward or dirt gradients that build up from the ground, are just a few of the examples. To make these work correctly, always aim to orient your UVs to match how the object exists in the world space.

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TEXEL DENSITY

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Texel Density (TD) is all about how many pixels cover a certain area of your 3D model. It helps keep texture quality consistent across assets and determines the texture size needed to maintain that consistency!

Think about it like this: a 1024x1024 texture can look crisp on a small object like a screwdriver but it would be low-res for something massive like a helicopter, making the larger object look blurry and out of place. Understanding TD helps you plan your UV packing and texture sizes for the best results.

TD is measured in pixels per centimeter (px/cm) or pixels per meter (px/m), often shortened to “ppm.”

Important to note, Texel Density isn’t the resolution of your textures itself, but it's affected by both texture size and the physical scale of your model.

But most of the time, we just need to be aware of what texel density we’re working towards, figure out the appropriate texture size and then let a tool like “Texel Density Checker” do the rest for us.

Here’s a more in-depth look at Texel Density: LINK TO TEXEL DENSITY LESSON

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PACKING ISLANDS

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Everything is inside the packing box here, example of an asset with unique texturing

The way you pack your islands can change a bit depending your texturing methods! There are the two primary methods. Assets with Unique Textures and Assets with Tileable Textures.We’ll be focusing on how it’s done with unique assets first.

For individual props and items, all of your UVs must be packed inside of a 0-1 UV space (refer to the beginning of this lesson to recap this concept). It is possible to have overlapping and mirrored islands that you will usually move outside the space when baking, but you will need to put them back inside the box for final export/import in engine.

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PADDING AND DILATION

After learning how to lay out your UV islands, the next step is making sure they’re properly spaced. This is where padding and dilation come in!

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What is Padding?

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In this image you can see how there is enough pixel space (padding) between islands. If they were closer together we would probably run into issues. You need to find the balance between maximizing the used space for a higher TD, and having enough space between islands.

Padding is just the amount of space (in pixels) between UV islands and the edges of your UV layout. It might look like wasted space, but it’s actually crucial to avoid texture bleeding. You can space things out manually, but if you want to be precise and optimize your UV packing, it’s recommended to use tools like UV PackMaster for Blender. It lets you set exact pixel spacing between islands and the UV borders. It’s a paid addon, but worth every cent. If you’re on a budget, there are free alternatives out there too. Do a bit of research to find what works best for you!

How much padding should you use? It depends on your engine and pipeline, but here’s a solid starting point based on texture size:

• 2048x2048 → 16px padding
• 1024x1024 → 8px padding
• 512x512 → 4px padding

For the margin between your islands and packing box, you can either keep the same distance, or if you want to optimize as much as you can you can give half of the space that you have between islands (if you have 16px space between islands, give 8px between islands and the margin of your packing box). This is because the 0-1 space tiles indefinitely, so you will have the space in pixels from both sides of your margins combined.

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What is Dilation?

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In this albedo you can clearly see the dilation working. The texture extends indefinitely from each UV island filling the blank space. This will help with smooth rendering on down-sampling/mip mapping processes.

Dilation is the process of filling in the empty space around the edges of your UV islands with color to prevent visible seams and texture bleeding! This is especially useful when mipmaps or lower-resolution versions of a texture are generated by an engine. Instead of leaving that space blank, dilation fills it with relevant texture data for smoother rendering.

LINK TO LESSON ABOUT MIP MAPPING

When exporting textures in Substance Painter, Designer, and other similar tools, you can select how much dilation (in pixels) you’d like the program to create. If you’ve already left enough padding between your UV islands, dilation won’t cause any issues. In fact, you can even use infinite dilation, which stretches the texture from each island all the way into the mid-point between two islands, like in the above image.

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OVERLAPPING UVs

UV overlapping is the process of stacking UV islands directly on top of each other, letting them share the same texture space to maximize efficiency. It’s a common practice, and almost every model has areas where overlapping UVs can be used. Since these islands will display identical texture details, be mindful of repetition — too much can make your asset look unnatural. The key is finding the right balance between optimization and visual variety.

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When SHOULD you overlap UVs?

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Repeating/reused parts, such as multiple identical elements, like 10 screws, you can model and unwrap the first one, then duplicate and reuse it, creating overlapping (identical) UVs. This way, you're only texturing one screw and saving space for the rest of your islands.

The smaller and more generic the element, the better it works to overlap UVs, as the repetition won’t be noticeable compared to larger, unique parts.

Symmetrical or mirrored elements are candidates for overlapping UVs. Since the mirrored parts are usually on opposite sides of a model, repetition isn’t as noticeable. For example, if you’re modelling a fridge, you can UV the left side and mirror the right side, saving space, while keeping the front and back unique to avoid visible mirrored textures. This way, you save a lot of UV space without any visible repetition, focusing on the areas that really matter.

The mirror modifier in Blender, will duplicate UVs automatically.

Repeating or reused parts are ideal candidates for overlapping UVs. Small, identical elements—such as screws, bolts, vents, or buttons—can be unwrapped once and duplicated. By overlapping their UVs, you texture a single element while all duplicates share the same texture, saving valuable UV space.

The smaller and more generic the element, the better overlapping works. Repetition on simple shapes is rarely noticeable, especially compared to larger or more distinctive parts of a model.

Symmetrical or mirrored elements work well with overlapping UVs. Since these parts usually sit on opposite sides of a model, mirrored textures are much harder to notice. For example, when modelling a fridge, you can UV one side and mirror the other, while keeping the front and back unique. This approach preserves visual quality where it matters most while significantly optimizing UV space.

Non-visible or rarely seen faces are also good candidates for overlapping UVs. If certain parts of the model are unlikely to be seen in-game—such as the bottom of an object or interior faces—you can overlap their UVs with other areas to avoid wasting texture space, as long as it doesn’t create shading or baking issues.

In Blender, the Mirror modifier automatically duplicates and mirrors UVs, making it easy to set up overlapping UVs for symmetrical geometry.

Overlapping non-visible faces works really well when you have parts of your model that aren’t likely to be seen, but you still want to keep the geometry for a cleaner model and to avoid potential errors. You don’t need the geometry to match perfectly to overlap UVs — though it helps if the shapes are somewhat similar. Going back to the fridge example: if you know the bottom face won’t be visible in-game, you can overlap its UV island with one of the side islands. This gives you extra texture info without wasting any space.

When overlapping UV’s you always need to offset the overlapping UV’s by at least 1 UV space.

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When should you not overlap UVs?

Unique or prominent details should not overlap. Any key features that draw attention such as logos, decals, text, serial numbers, or highly detailed parts of the mesh, need their own UV space. Overlapping these areas will cause visible repetition or mirroring, which quickly breaks realism.

Larger or hero props should be handled carefully when it comes to overlapping UVs. The larger and more important an asset is, the more noticeable texture repetition becomes. Overlapping UVs can make texturing harder and reduce visual quality, so these assets usually need more dedicated UV space to maintain consistency and clarity.

Areas with unique wear and tear are poor candidates for overlapping. Real-world wear is rarely symmetrical—scratches, chipped edges, dirt buildup, and rust patterns are all irregular. Overlapping UVs will force these details to repeat in unnatural ways.

Faces that are likely to be seen at the same time should not share UV space. For example, surfaces that face each other or are visible simultaneously in-game—such as the front and back of a character or the inside and outside of an object—can create obvious texture repetition or visual mismatches if overlapped.

Textured assets that rely on baked maps (such as normal maps, ambient occlusion, or curvature) generally require unique UVs. Overlapping can cause baking artifacts, lighting errors, or incorrect shading, since multiple surfaces are trying to use the same texture information.

As a rule of thumb: if the surface is important, highly visible, or needs unique detail, it deserves unique UV space. Overlap UVs only where repetition won’t be noticed and won’t interfere with the final visual quality.

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UVs FOR TILEABLE TEXTURING

The second method relates to Tileable Texturing. Tileable texturing is where, instead of only using a 0-1 texture space, a texture repeats (”tiles”) seamlessly over a surface without any visible edges or breaks. This is often used for things like floors, walls, fabrics, or anything that needs to cover a big area without stretching a single texture too much.

LEARN MORE ABOUT TILEABLE TEXTURES HERE

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Tileable textures examples

Instead of unwrapping and packing an object in a 0-1 space, and uniquely texturing, say the above tower, you may unwrap it and apply a tileable texture that loops infinitely, only scaling up or down the UV to adjust the Texel Density (modifying how big or small the tiling pattern will be).

This saves UV space and texture memory. It's a great way to keep textures looking sharp while optimizing performance, especially in games where unique textures for everything would be waaay too heavy. The main priority with Tileable Textures is keeping their Texel Density exactly at the target value. If you need a specific detail to show up in a certain area, you can adjust your UV islands to match that detail.

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Trim Sheets

This is where trim sheets come in!

Trim sheets are a super efficient way to texture assets, especially for games and large environments. Instead of giving each model its own unique UV layout and texture, a trim sheet is a single texture that multiple assets can share by aligning their UVs to specific sections of the sheet.

Imagine a texture with different types of trims, panels, and surface details laid out in strips. You map different parts of your model to these strips, letting you reuse the same texture across multiple objects while keeping them looking detailed and high-res. This method is great for things like walls, pipes, railings, and architectural details, where you don’t need unique texturing for every single piece.

Since trim sheets don’t follow the usual 0-1 UV space rules, you can tile them as needed, scaling and repeating sections to match the asset’s dimensions. They’re a game-changer for optimization, cutting down on texture memory usage while keeping visual quality high.

If you’re making modular pieces that need to tile seamlessly, you’ll have to make sure the end of one UV island lines up perfectly with the start of the next. This is usually done by snapping them to the grid or aligning them with the boundaries of the 0-1 space, depending on your target Texel Density and scale requirements.

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LEARN MORE ABOUT TRIMSHEETS HERE

Here is an example of a modular building that makes use of both tiling materials and trim sheets.

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SOFTWARE OPTIONS FOR UV UNWRAPPING

Most modeling software includes its own UV mapping tools, however some standalone software is also available specifically for UV unwrapping.

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TROUBLESHOOTING COMMON ERRORS

Incorrectly made UVs can cause a couple issues. Here are some typical issues!

Jagged Edges along Seams

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When you see thin jagged artifacts along the hard edges of your model, it is because you haven’t placed seams on those hard edges, or there isn’t enough padding between the islands. The reason for this is that the baker is trying to calculate the normal values of your bevel from both angles, leading to some pinching in the normal map along those hard edges. The fix for this is to simply include seams along all hard edges, and give the UV islands enough padding, resulting in a smoother transition between the UV islands.

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Baking errors

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Having overlapping UVs in a 0-1 space will mess with with baking. This will cause errors in the bakes and affect texture application. The fix is simple: move your overlapping islands outside the packing box before baking, do your bakes, and once done, you can move them back to their original position (just make sure to offset them properly to avoid any issues). It’s a quick workflow to avoid those errors and keep everything clean.

Noticeable repetition

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You don’t want to have objects with overlapping UVs that are too big/important, easy to identify or very close to each other. You need to be smart about what you choose to overlap, and also try to do as much as you can to hide that repetition. Applying different transforms to your objects with overlapping UVs can solve this problem too, a different rotation or a small size variation can go a long way in breaking that perfect repetition.

Butterfly effect

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This is something to watch out for when mirroring a face with a symmetry modifier, especially if it’s right down the middle of the object. While mirroring is great for saving time, any detail placed at that center line will be repeated on both sides, creating a “butterfly” effect. It might look fine for some cases, but it can lead to obvious, symmetrical repetition that stands out.

To avoid this, place key details slightly off-center before mirroring, or plan to add subtle asymmetry afterward by adjusting one side manually. You can also add variation through layered texturing. Use decals, vertex painting, or procedural textures to break symmetry, giving each side unique details to hide mirrored geometry.

Provide solution to this issue here!!!

CONCLUSION

UV unwrapping can feel intimidating at first, but like any skill, it becomes easier and more intuitive with practice. Every model you unwrap builds your problem-solving instincts and your understanding of how textures interact with form. Don’t aim for perfection on your first pass: aim for clarity, cleanliness, and intent. During the early baking and texturing stages (the next steps!) of the modeling process, artists often continue refining their UVs to make sure everything is visually correct.

Remember that strong UVs are doing a lot of the heavy lifting behind the scenes. They give you control, consistency, and the freedom to focus on creativity instead of fixing errors. Treat unwrapping as part of the artistic process, not just a technical step, and you’ll see your future textures improve faster than you expect.

Now it’s time to put these UVs to work. Let’s start baking!