Assalamualaikum. My name is Widhi Muttaqien from expose academy.
The causes of UV map tilting problem
When we do UV unwrapping in Blender. There are times when the resulting UV layout is perfectly straight like this. But on different occasions, sometimes they are tilted like this. Some people think that this is just a random behavior of Blender’s UV unwrap algorithm. Well, actually this is not a random behavior, and we can easily recreate the problem. Okay, so what is actually causing the problem then? After experimenting for some times, I found out that this UV tilting problem can happen due to 2 reasons. The first and the foremost reason, is the dimension of the model. For example, these boxes. The edge seams assignment for both of these boxes are the same. But, they have different dimension. The first one, which is generating the correct or the straight UV layout, has a dimension of 12 unit in X axis, by 5 unit in Y axis, and 6 unit in the Z axis. And then this box, which generate crooked or tilted UV layout, has a dimension of 12 unit in the x axis just like the first box. But notice the dimension for the Y and the Z axis are identical which is 5 unit. This actually what causing the tilting problem when UV unwrapping. So essentially if you have object, with at least 2 axis dimensions identical or very similar in values. It can be X and Y, or X and Z, or Y and Z. Or even all of them, X ,Y and Z, have the same or similar dimension. This will make the object to have UV tilting potential. Okay. Now you might be wondering, why am I saying that this is just a potential? Well it is because the second reason of why UV tilting happens. The second reason is because the edge seams assignment. For example this box has the Y and the Z axis dimension identical. It has 12 unit in X axis, and 5 unit for both the Y and the Z axis. Basically it has the same dimension with this box. But it has different UV seams combination. Notice if we select all of the faces then U then U again unwrap. We still get nice perfect straight UV layout. So as you can see some edge seams combination can cause the UV tilting problem, while the other combination will not causing it. But in my experiments, these edge seams combination can only create the tilting problem if the first reason exist. So again, the second reason only happens if the first reason exist.
Okay, now we know what causing this UV tilting problem. But what if we actually need the dimension to be similar and or we need to have that certain UV seams combination which causing the UV tilting problem. How can we fix the UV tilting then?
How to fix UV tilting fast
Well there are many methods that we can use to fix the UV tilting problem. We can use the “follow active quad” method. Or we can use, more manual align method. In my Udemy course which is “Blender 3D from zero to hero” I actually explain a lot of these techniques in more in depth. But in this tutorial I’m going to show a quick easy way to fix tilted UV layout like this.
First open the UV image editor. Make sure we are in vertex mode. Basically we want to align these 2 vertices only. We can actually pick any 2 vertices that we like, but lets just focus on these 2 vertices. To align these 2 vertices, one common way to do this is to use the auto align method. Make sure the two vertices are selected, press W and then A. So basically the W shortcut will open the “weld align” panel. And the A shortcut, is to use the “align auto” in here. Okay this method is a very common method and most of you guys perhaps already know about this method. But the problem with this method is that both of the vertices are moved. If this is not a problem for you, then you can use this method.
But right now I want to show you an alternate method. And with this method, we can move only the selected vertex, for example the bottom one only or the top one only. It is up to you. Let me undo the “align auto” command before. So we are back with our initial vertices position. Okay. Basically we want to move and snap this vertex, so it aligns with this vertex at the bottom. First make sure the snap option in here is set to vertex and the “snap target” is set to closest. But do not turn on the snap mode button in here. So snapping is currently off. Okay, now we want to move this vertex horizontally. Usually we do this by using the G shortcut and then X to constrain it to X axis. We want to use a different method now. To move this vertex horizontally, right click and drag and then try to move the vertex in horizontal direction, then press and release the middle mouse button. Notice Blender will detect our initial movement and then determine that we actually want to constrain to X axis. Okay now in this condition, hold control, this will activate temporal snapping. Move our mouse cursor on this vertex. And as you can see the top vertex will align perfectly with the bottom vertex. I know it seems a bit hassle at first to do this. But trust me once it is in your muscle memory you can do this faster than having to press G and then press X or Y. Oh yes, also you can actually do this in modeling session inside the 3D view editor.
Okay, after we have these 2 vertices aligned perfectly. Select both of them and pin them by pressing P. You can find the pin command also in the UV menu down here. But using shortcut is always faster. And I know almost all Blender users are shortcut lovers. After we have these 2 vertices pinned like these. Next, we need to perform another UV unwrap. Now, you may already know how to UV unwrap in the 3D view editor. Which is basically pressing U and then U again. In the UV image editor though, it is actually much simpler. Just press E shortcut. Now as we can see we have this instant straight UV island. You might be wondering by now, how can this be possible? Well, it is because we have these 2 vertices pinned. When Blender try to UV unwrap the whole UV island, it can not move these 2 vertices, therefore what is happening here, the other vertices will yield and follow these pinned vertices instead.
Okay guys, I hope this short tips video can help you fix your tilted UV layout faster. If you want to learn Blender from zero, and master all of the in-depth 3D skills, in the shortest time possible. Then you should join my new Udemy course. I have the link with discounted coupon code in the video description below. And as always, subscribe to my channel, share the video. Give a thumbs up if you like the video, and give a thumbs down if you hate the video. Check out my other tutorials. Wassalamualaikum.