No edge loop issue with marking seams

Hey everyone,
I looked up many tutorials on UV map creation and attempted my first UV mapping project here. I intended to do this by symmetrizing one half of a complete mesh.

Given that this is a triangular 3d model without edge loops, I’m finding it difficult to tell how the system interprets the seamed edges. This brings up a bigger issue. The islands created on the UV map have no definite structures. They are just all over the place with random pieces here and there. The worst are those small fragmented triangular pieces appearing, that depict some random face triangle from the model.

Any advise on how I can do this correctly? Is doing it on half a model a good idea?

seamproblem.blend (632.4 KB)

Although you only have half a model here, if you were to add a Mirror modifier and apply it you would find you have some faces stuck inside the model. These are the ones that are causing some of your UV map to have overlapping areas. You also have some edges marked as Sharp dotted around. Were those meant to be marked as Seams as well?

Ah… You have a whole model, but half of it simply hidden. Remove all the Sharp edges. Remove all the vertices, edges and faces that are going to end up inside the model. I’d forget about trying to symmetrise the UVs. The model is simple enough for you to place seams on all of it without trying to mirror things. The model isn’t symmetrical at the moment - especially at the end of the tail.

If you are going to use the Mirror modifier or symmetry then you are probably best just deleting half the model instead of just hiding it in Edit mode. As it is at the moment you are trying to UV unwrap half a model. The triangle nature of this model doesn’t help when trying to work out what’s going on.

You’d be better starting it really simple. Seams straight down the belly, around the neck, around the root of each limb. Unwrap. Then start cutting in seams along the length of each limb. Unwrap. Adding some seams then selecting all and unwrapping can help you get a better idea of what’s going on, rather than trying to work out where to put every single seam before unwrapping. Using the wee button to keep UV and Edit mode selections synced helps as well when trouble rears its head, but I think you had that turned on.

Ah… You have a whole model, but half of it simply hidden.

My apologize for not clarifying that detail in my original post. Yes, half the model is hidden. I intended to delete the hidden part, and use the symmetrize function to mirror the complete half to make the model whole again.

Remove all the Sharp edges. Remove all the vertices, edges and faces that are going to end up inside the model. I’d forget about trying to symmetrise the UVs. The model is simple enough for you to place seams on all of it without trying to mirror things. The model isn’t symmetrical at the moment - especially at the end of the tail.

If you are going to use the Mirror modifier or symmetry then you are probably best just deleting half the model instead of just hiding it in Edit mode. As it is at the moment you are trying to UV unwrap half a model. The triangle nature of this model doesn’t help when trying to work out what’s going on.

This is where it gets complicated. There are indeed some unwanted stray faces, vertices and edges inside the model which I don’t know how to find easily since they can be very small or difficult to see, and that too for one half of the mesh only. Trying to do it for both halves would be double the difficulty.

What can I do to make this easier?

There were only a small number of unwanted faces, so deleting them manually is usually the quickest option, but the biggest issue is conflicting face-normals - this means the smoothing will never work and you will get render errors.

There’s a setting in the overlay menu to show which way face normals are poinitng, the inside of your dinosaur should be entirely RED and the outside BLUE, but it’s a mix. After deleting unwanted faces/vertices and edges, the model needs to have it’s normals recalculate on outside ( in mesh nenu).

But it’s Saturday :slight_smile: so here’s a cleaned up file. I’ve removed half the mesh and added a mirror modifier. I’ve done nothing with the UV seams.
seamproblem_fix.blend (597.5 KB)

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Thank you for that important insight DamianJ. I always knew that the lighting on the model on its various parts were wrong and needed to be addressed at some point, but my knowledge of normals is limited. Thanks to you, I’m now understanding this more. Also, I really appreciate that you did the work on the model, even though you didn’t have to.

However, I can’t open the file you have sent (seamproblem_fix.blend). I suspect its because I’m using regular Blender 2.79 (because I don’t want to lose the compatibility of some of the plugins I have). Which version do you have?

Hi. It’s a 2.8 file. If you open it in version 2.8, delete the mirror modifier then export the mesh as an fbx you can then simply import the fbx into Blender 2.79 and reapply the mirror modifier. Be sure to check the scale of your imported mesh - the fbx can change this depending on export/import settings, so you may have to rescale manually.

I’ve just realised, that rather than export and import as an fbx, you can simply APPEND the object from my 2.8 file. From within 2.79 . . . select Append from the file menu, then select the ‘fixed’ file, and in the submenu select Object, inside here is your obj1.001 model. Pick that and et voila. When this imports it will have the mirror modifier already in place and the material will not be changed to fbx sphagetti.

I’m not sure if this is meant to be right or not. The black section’s faces can’t be selected either.

Somehow I get the feeling something went wrong.

There are a few ways of making it easier:

  1. Basic stuff - like selecting a section of outside faces and hitting H to hide them. This lets you see if there is anything obvious lying behind them.

  2. Wireframe mode can help. Sometimes it helps you spot inside edges (where you’ve accidentally connected a vertex on the outside of the mesh, through the mesh to a vertex on the other side.

  3. The selection menu. You can get it to search for non-manifold issues, interior faces and the like. This won’t work as well if you face normals are still messed up. How is Blender to know what the interior is in that case. That also causes other problems. It’s hard to ask Blender to make normals consistent when you have faces inside the mesh.

Looks like you are making progress though.

Thanks @DamianJ for reminding me about that red/blue normals thing. Much handier than turning on those annoying wee lines that jut out from the faces.

I had a quick look at the file Damian made for you, in both 2.8 and as an appended object in 2.79. Appending seems to change these options in the N panel. Turn the ones on that are on by default (plus Seams - Seams is off by default but automatically turned on when you mark a seam)

image

The colouring is something to do with the fact that there are different materials assigned.

image

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John, thanks for the follow-up info for @Hornetzero.

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@JohnMalcolm1970 Thank you providing that useful information John. Now the modified model appears correctly. I also thank you for giving me insight on how to locate stray vertices/faces and edges on the model. I really appreciate your input

@DamianJ Now that I got to work with your file in its modified state, I thank you very much again for your time on helping me with this. Now off I go to UV mapping this.

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I realize this was resolved 2 days ago on matters of model geometry, but the actual issue pertaining to UV unwrapping with marking seams is still unresolved. I’m sorry to bump this topic back up but I require help again, since I have tried everything from marking my model’s seams correctly according to various tutorials shown online, to trying projection (which are almost unpractical given that I don’t have suitable texture for that and I using projection mapping for the entirety of the model would make it difficult to make modifications), yet the unwrap results are almost, always very poor.

Most of the islands are disproportionate and I’m at a loss of ideas on how I can setup UV mapping that would allow me to map on textures like these:

Here is the file with the updated seams:

ArmadonSunday26Feb2.blend (485.1 KB)

Hi @Hornetzero. I think the issues you are having are related to how you are thinking about the uv Unwrapping, not the unwrapping itself. The map you have created is valid, and will work, but I fully agree is not ideal. This is going to be rather a long post, so bear with me :slight_smile:
Imagine your model was made from paper, cut and glued together. Unwrapping is the equivalent of trying to figure out how you would cut it up in the most efficient manner [ ie fewest number of pieces ] that would permit you to lay each part as flat as possible. And then to make sure it really is flat you place a huge book on top of your cut out paper. If the seams you have cut along are not good then the paper will scrunch up and you’ll get a mess, but it will be FLAT!

Unwrapping has the advantage of not actually scrunching up bad seams, but it will distort things badly. Which is the issues most obvious in the tail of your dinosaur, caused by all the small ‘horns’.

Here’s a simple object comprising 4 identical geometries - a cube with a pyramid on top:-

On the left are 4 possible unwrapping solutions, one for each geometry.

  1. This is the ‘simplest’ cut, but notice how completely distorted every face is. Not a single face is a square even though it’s obvious from the geometry that it should have nice clean straight sides.This is the primary issues you are having with all the ‘bone-horn-thingies’ along the tail.

  2. This looks better, the faces of the cube are now squares, but what’s the deal with the point of the pyramid? Well, it’s there, but in the unwrap bears no relationship to it’s actual size in the geometry! this is because the seams [ or absence of them] don’t allow the faces that define the pyramid to be expanded, therefore it HAS to be squashed into that place ( this is the book analogy from above ). Your model also has this issue with horns and ‘spikes’.

3/4. These represent the two most useful unwraps because each face is a flat as possible and if you were to cut either of these out of paper and fold and glue it, you would get exactly the model shown. Which of these you would use is more: an aesthetic consideration, depending on where the seams might be visible; or a packing consideration, on how easily it fits into a UV space with other meshes.

Your dinosaur will not lend itself to as clean a solution as this, unless you literally face map the entire model, but then the unwrap will be meaningless visually as you won’t have adjacent faces connected. But it is a solution in some circumstances.

Finally, before I exhaust everyone’s patience, it’s not clear if you want to use the map of the dinosaurs that you show. However, if that is the case:

I’ve not changed your seams at all, but what I have done is simply move the UV vertices around for the head, so that they align, as best as possible, with the geometry. Notice the stretching and distortion, this is unavoidable, and there are no real short cut to do this, unfortunately. It will require you to go back and forth between seams and vertex manipulation, until you get what you are after.

UV unwrapping is complicated, that’s why software is written explicitly do just that, here’s a Blender add-on in a thread on this forum:

I hope this post has been of some use. Here’s your [ ammended] blend file with all the things I’ve outlined in this post in it. You may need to load in the map image yourself, to see it on the geometry.
ArmadonSunday26Feb2_DJ_1.blend (617.4 KB)

All the best, Dj

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Well DamianJ, your post was incredibly insight, and stands to be a good tutorial on its own to post in my deviant art page, given that a lot of things you have outlined aren’t so very obvious in most tutorials I have seen so far.

I thank you greatly and appreciate all you have done for helping me.

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For this kind of texturing you should also look a little into Texture Painting. When I started playing around with Blender a lot more, the first project I tried in a long time was a 3D model of one of my old 2D digital paintings of a dragon. I have learned a lot more about UVs, texturing and lighting since then. This model only had a fairly simple texturing, but the main point being - I didn’t UV unwrap it very well at all, and all the colouring was painted straight onto the model in Blender.

I might revisit this model now and see how it can look with a bit of Substance Painter and some better texturing.

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