3D models use a system called “UVs” to control how graphics, images, and textures are applied to the model. UVs are a representation of a 3D model flattened into 2D space. In this article, you’ll learn how to export these UVs from Dimension and create textures in other applications like Photoshop and Illustrator.
What are UVs
UVs are a representation of a 3D model flattened into 2D space. Imagine taking a cardboard box, cutting seams, and then flattening it out. That’s essentially what UVs do for your 3D model! The 2D image is applied on a coordinate system, known as UV space, on the flattened version of the model. It is then projected back, matching the UV coordinates with the model’s geometry, and rendered on the model surface.
UVs are created in a few ways. When a 3D modeling program creates a new model, it sometimes auto-generates initial UVs. These UVs are often not ideal for texturing though, as they have many seams, overlapping parts, and aren’t artistically arranged for easy use. An artist creating the model can choose to “unwrap” UVs manually by dividing the model into logical parts, artistically placing seams, and arranging the UVs for use. Many applications also have automatic UV unwrapping for full models, including Dimension.
Use export UVs to create images for a 3D model
You can consider UVs a map for how an image is going to be applied to your model. Using this map you can design and place images specifically to align with the features of a model.
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Select a model you want to create an image for.
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Use the Object > Export UV menu option, then select a resolution and location to save your UV image to.
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Open your UV image in your editor of choice, such as Photoshop or Illustrator.
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Design your graphics for the model using the guide layers for assistance.
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Save the UV image. Reapply the image onto your 3D model as a graphic layer with the mode set to fill. Graphic layers will have their own material properties like metallic and roughness.
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You can also reapply the image directly into a material property, such as base color.
As part of the material properties, the image will only apply to that property. In this example the bottle material is slightly metallic, so the graphic maintains that attribute.
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You can use the Edit command to continue to edit the graphics and see updates between your 3D scene and Photoshop or Illustrator.
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When you’re satisfied with your final design, turn off all the guide layers and save or apply your final artwork to the model.
UV guide layers
UV export will generate a .psd format image for your models UVs with several guide layers to help with the process. Each layer serves a purpose and is outlined here.
Outlines
UVs are created by artists or generated by machines and are often segmented into areas called UV Shells. The Outline layer shows the seams and edges of these areas.
Non-editable area
UV space is always in a 1:1 ratio space, so when UVs often don’t use 100% of the image area. The Non-Editable Area layer shows which sections are outside of the UVs and won’t show up on the model surface.
When to use UV export
Dimension has many ways to apply graphics to your 3D models. All of these methods can be combined:
- For isolated logos, labels, and floating elements, you can drag-n-drop an image directly onto the model to place it as a graphic layer. Use “Decal” mode to place the graphic on the model freely.
- For repeating patterns that fill an entire area, drag-n-drop an image directly onto the model to place it as a graphic layer. Use “Fill” mode to place the image, then use the repeat, rotate, and offset properties to tile it.
- For designing details that match features and seams of the 3D model, use UV export to get the models UVs first. Design your graphics in Photoshop or Illustrator. Place the image back on the model as a material texture or graphic layer. For graphic layers, use “Fill” mode to fill the image to the models UVs.
Troubleshooting UV export issues
As discussed in this article, UVs are an entire system for mapping a model into an image space. Many 3D modeling tools include a toolset for “unwrapping” UVs, to create artistically arranged UVs. UV Export does not include mapping tools for controlling how the model is unwrapped, it exports existing UVs. There are some limitations that are important to be aware of.
You can use the menu option Object > Generate UV to replace the current UVs of your model with automatically generated UVs from Dimension. Generated UVs will never have overlap and will minimize distortion, but may have many areas and seams and will not be artistically arranged. When you generate UVs, you’re changing the mapping of images and materials to the surface, so existing materials or graphics may change how they look. It is recommended that you generate UVs early in the process before doing much material and graphic work.
Here you can see a comparison for two types of UVs for the same coffee cup object. On the left are UVs created by the original artist and are artistically arranged to take the best advantage of the image space and are easy to understand. On the right are UVs that were automatically generated. The model is cut into more pieces and the space isn’t used as well, but it requires no manual work.
Overlapping UVs
In UV space a common technique to save space is to overlap pieces that share details. For example, a symmetric object may be modeled and then the model and UVs are mirrored. Overlapping the UVs means that the image in that area will also be overlapped.
To resolve overlapping UVs, you can use the Object > Generate UV menu option. Dimension will auto-generate UVs that do not overlap, though they may still have distortion and illogical seams.
Distortion
UVs can be squashed and stretched. Usually the artists and UV unwrapping algorithms attempt to minimize distortion, but it’s sometimes impossible to have UVs be completely distortion free.
You can sometimes distort the graphic in the UV Image to counter the distortion in how it’s applied to the model.
Seams
When UVs are created the model is broken into areas, called UV shells. Each UV shell has seams that cut the surface so it can be laid flat in UV space. Seams in UV space also mean seams in the textures, which isn’t always a bad thing. Logical seams can break the model up for texturing easily.
Sometimes seams may not line up between different features of the model in UV space, or may be placed in a way that makes creating a graphic across the seam difficult. Graphic Layers in decal mode are projected across seams. You can combine UV Export and decals as needed.
Poorly made UVs
Often the result of auto-generated UVs that have never been looked at, sometimes UVs are jumbled up. The result is usually that the UVs are messy or impossible to work with.
To resolve poorly made UVs, you can use the Object > Generate UV menu command. Dimension will auto-generate UVs that do not overlap, though they may still have distortion and illogical seams.