Export model UVs as images
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.
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.
When to use UV export
Dimension has many ways to apply graphics to your 3D models. All of these methods can be combined:
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.
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.
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.
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.