In this short tutorial, we will see how to retrieve UV seams in a 3D model that does not display edges marked as Seams in Blender.
Video Transcript
Hello everyone! In this short tutorial, we will see how to retrieve UV seams in a 3D model that does not display edges marked as Seams in Blender.
This is a basic tutorial, made with version 3.3 of Blender, but the tool shown here has been available for several versions of the software and is likely to be available in the future as well.
In some cases, you might need to fix the UV seams of a 3D model that has been provided to you as properly unwrapped, but you cannot find the UV islands in the 3D model imported into Blender.
As an example, I'm importing a 3D model, downloaded from the Adobe 3D Stock website, using File Import OBJ.
The issue with 3D models in OBJ format is that they do not contain information about the Seams originally used to unwrap the UVs of the geometries.
Switching to Edit mode with the model selected, we indeed notice that there are edges highlighted as Sharp, but the Seams of the UV islands are not available.
As a side note, you can remove the Sharp marking by selecting all the vertices of the model and pressing the CTRL E shortcut, then selecting the Clear Sharp operation from the menu that will appear on the screen.
In Edit mode, let's switch to a UV Editing type display layout, so as to have both the view of the model's UV seams in a UV Editor window and the 3D model in a 3D Viewport view.
As you can see, the model's UV unwrapping has retained the subdivisions into islands of the original model, but the geometries do not display Seams.
To retrieve the original Seams, all we have to do is select all the elements in the UV window by pressing the A key, then open the UV menu and click on the Seams from Island tool.
It's very easy, isn't it? Now we can modify the original UV seams.
Alternatively, we can select the islands as I showed you earlier, for example, to hide all the rest of the geometry and perform operations only on the UV island that interests us.
Or, we can simply arrange the same islands on the UV plane according to different criteria, depending on our needs.
UV islands, bounded by edges highlighted as Seams, which appear in red in Blender's 3D Viewport, are not only useful for unwrapping the UVs of the model but also as a selection tool.
In fact, it is possible to select a UV island very quickly in the 3D view in this way:
switch to the Faces selection mode, in Edit mode;
position the mouse cursor over a face or an edge of the island you are interested in selecting;
finally, press the L key, which is the shortcut for the Linked operation.
This will allow you to quickly select the island, which you can then isolate from the rest of the geometry and modify as you like.
I hope this short tutorial has been helpful! See you soon!