Hello everyone, I’m trying to unwrap the upper hull of the CSS virginia (which in my approximation is somewhere between a cylinder and a cone shape).
I’ve tried unwrapping and then aligning the hull using the base unwrap from the image attached. However, after aligning everything along the X and Y axis, there was still obvious distortion and I’m just lost at to where to go from here (Unwrap a different way? Aligning differently?). Also, is there a way to force Blender to unwrap an object without ‘curving’ it? I had anticipated it would unwrap like a cylinder or cone, instead it came out like a stapler…or something.
Eventually this hull will get a tiled ‘iron panel’ texture which is why I tried to get the unwrap ‘flat and level’ because the panel lines in the front and back are completely wrong (horizontal instead of vertical) with a more basic continuous unwrap.
Any ideas are appreciated, thank you for reading.
Important Note:
-This is going to be a 3D model used in a iOS game, which means that as far as the poly count, texture size, and number of textures go I am fairly limited.
Yup, I’d split it for’d as well as aft so you get two halves the same as each other. Use a mirror modifier to make things easy, so you only have to unwrap one half. The you can rotate and align the UV’s if they still come out wonky (which they probably will).
Thanks to both 0BackBONE0 and Gumboots for your ideas and work. I tried more splitting as suggested, and the results are…well…better.
I tried using the mirror mod idea and splitting the bow and stern sections (which you can see the ‘in progress’ Uvs for that). Unfortunaltey the distortion is still significant up close, and as you can note in the other much more accurate 3D rendering of the Virginia (done by “the hankster”), the side and front/rear panels are ‘flat’ relative to a North/East/South/West orientation, and I tried hand fixing the stern/bow uvs to match that and it was an abject disaster.
I’m quite defeated at this point, I’m trying some projection unwraps instead, hopefully I can get something out of that.
Just tried some projection unwrapping, still trying to figure out how to remove the distortion on the tops of the bow/stern section and how to align the sections…
I’m no UV unwrapping expert myself since I only recently started using Blender. I’ve found various sorts of unwrapping weirdness with my pet project (locomotive model) where I just know the unwrap is distorted.
What I did to get around that was work out a projection of the part mathematically, then haul the damned UV’s to the right points that way. With simple shapes like this, I think it’s probably the way to go if you want them geometrically accurate.
ETA: Come to think of it, I suppose I could also do it by unwrapping developable shapes in Delftship and using that as an overlay to haul the Blender UV’s into shape. That could work, since ship design apps have very good plate development algorithms.
@Gumboots:
“work out a projection of the part mathematically”
-Could you elaborate on that at all? I’m not quite sure what ‘process’ or steps you would need to do that.
This is my latest attempt, the ‘junctions’ actually do lineup fairly well (my goofy alignment image aside), but there are still pesky distortions…I think I need a different approach at this point.
Hello eppo, thanks for the idea, I’ll give it a try (Its just that this model is going to end up in a mobile game and the hull mesh doubles as a collider, so more geo = more computation time (generally speaking). This is why I have been hesitant to throw more geometry into the model if at all possible).
Not quite sure what you mean with “love all square notion somewhere around” (I’m guessing English isn’t your first language?), but is it something along the lines of: Ideally every UV face is a square, and that the more you get away from a square the more susceptible to distortion your UV map becomes?
You’re right - English is my third; nevertheless you deciphered what i was trying to suggest ;).
Too bad you have to be low on resources but then what do you expect being actually rendered on screen? Does this project assumes a lot of slow paced closeups on this particular detail taking all screen estate? If not, you probably need to make some “real world” test to be sure these distortions are visible at all.
Day before we were discussing this issue and i cant say i see much of such distortions on a quick model which actually does break “more squarish - better” theory. Maybe there are but as approximately 1/6 of full HD screen it’s not like greatly visible. http://www.pasteall.org/pic/show.php?id=91570
Edit: almost forgot- i did use Project from View, top; this might be the reason why plank lines are not distorted. This could distort any painted grain though; then you could use 2 unwraps and bake combined texture. (Do they really used metallic or metal covered planks for this ship? It’s much easier to put on metal sheets later imho…)
The superstructure on this ship is a basic conical development at each end, which means getting an accurate expanded shape is just a matter of using some trigonometry. Once you have the vertex locations from trig, you can use those to place your UV’s. Although it might be just as easy to distort your image to fit whatever UV’s Blender throws at you.
I get the impression that Blender’s expansion algorithms are geared more towards modelling things like humans, where you’ll never be able to calculate the geometry yourself anyway and just need it to look good once it’s all finished. They often seem to fall down on hard surface modelling, even for shapes that a dedicated app would eat for breakfast, and when and where they’ll fall down doesn’t seem to be predictable. The only one I’ve found to work reliably for proportions is the “Project from view” option, which often isn’t suitable.
may be another way download the unwrap then work in GIMP to add image over
but good point the outside is made of large metal plates and not small pieces I think
problem is that we don’t really have good color picture for this ship
@Gumboots: Interesting, thanks for the elaboration.
@eppo:
“slow paced closeups”
Well, these ships are definitely slow (even when sped up two or three times the real world values), and the fighting range for these ships in general is actually fairly close. I just didn’t want anything obvious, I can live with small issues.
“i cant say i see much of such distortions on a quick model”
It seems to me that the ‘cut outs’ for the ports is what makes the UVs so crazy. I’ve also done some test models on more basic shapes and they come out pretty clean. But as soon as the ports get added, here comes the crazy…
@RickyBlender:
" the outside is made of large metal plates and not small pieces I think"
Well, in the case of the Virginia (and others) the tricky thing is that this ship had so many versions / modifications that its hard to pin down any exact configuration. The ‘artist renderings’ from the time don’t tend to be very accurate either, so the best ‘real examples’ are from wreckage and random blueprints / plans (but those are also consistently inconsistent).
The other issue (and reason I wanted to try tiling a texture) is that details like bolts/rivets shrunk down to scale on a x1024 texture usually come out looking like blurs or ‘flat circles’. Using a tiled texture allows for better resolution. Now I could add ‘bolts’ as a second texture and tile that, but then I lose control of patterns / layout (and mobile procedures generally discourage multiple materials per mesh, so there is that problem to).
As an aside, there is the armor thickness for the USS Monitor’s turret, so I can appreciate why the south in particular (with less industrial machinery available to them, might want to break armor into slabs (I’ve seen armor represented from completely flat single pieces all the way to tiny slabs (almost like corrugated roofing), so in the end, I’ll do ‘what looks best’).
depends if you must have close shots almost photo realist too!
show us what you got up to now
you could add rivets with normal map
but again normal maps work if it look at with same angle camera it was taken
any other angle and the 3D effect begins to loose it’s effect
also true for bump maps
did u find some good blueprint showing the metal plates ?
can you give link
if you need very close shots then do a real model !
“Ahh, yes … rivets and cast iron! My kind of era!”
The first thing that I would recommend is that you look at the actual ship and that you model the hull as individual plates, not a single mathematical surface. Start with a surface but go to polys.
For longer shots, I would simply use a model that has been texture-painted. (“Meh… good enuf. Let’s move on.”)
But there will be other models, probably of just portions of the ship, which will need to be modeled after the way that the ship was actually constructed. For instance, if you were going to re-create that shot of General Somebody inspecting the ship, I think that you should model the individual plates, and lay your iron-plate texture over them oriented exactly to zero-degrees. Actually, there would be several layers of texture.
You might use local coordinates in the mapping because, say, the UV-map of a rolled iron plate bent around the bow of the ship would not be a curved shape on the UV map: it would be a polygon. You basically can’t have “curves” on that map. At some point in time, before it was bent or cut, that iron plate was flat.
What these people had at their disposal was basically what all shipbuilders use: a rolling mill which could make cylindrical shapes and tools to make bends of sharper angles, from which the final plates were then cut. The texture is that of a flat iron plate, and it maps to the local coordinates of that plate. The entire ship that is within-frame is seen to consist of plates, which were made from different batches of steel at different times.
There is an excellent museum at the Tredegar Iron Works in Richmond, Virginia whose archives include shots of the ships under construction and of iron being prepared for them at the plant.
How about just using alpha to do the ports? Much simpler mesh, and should look ok.
@RickyBlender:
" the outside is made of large metal plates and not small pieces I think"
Well, in the case of the Virginia (and others) the tricky thing is that this ship had so many versions / modifications that its hard to pin down any exact configuration. The ‘artist renderings’ from the time don’t tend to be very accurate either, so the best ‘real examples’ are from wreckage and random blueprints / plans (but those are also consistently inconsistent).
This is actually a bonus for you, because whatever you do nobody can say it’s wrong.
I made sure to add a note about how this model is going to be used in a mobile game.
@RickyBlender:
“did u find some good blueprint showing the metal plates ?”
-If you want a quick idea, just search “CSS Virginia / blueprints”. I don’t think I found an actual period blueprint that shows the armor in detail, though I have for ships in the same class as the Virginia.
@sundialsvc4:
-Thanks for some info on the shipbuilding side, very interesting. To your other points about creating the 3D model, you may have missed that this is for a 3D mobile game in the comments (I added it to the first post). So in that way, I am very limited in what I can do for the ship. At this point having tried the tiling solution, I think it is best to do a traditional UV map even with the lower resolution that comes along with it.
@Gumboots:
“How about just using alpha to do the ports?”
-Ah, it is a issue related to this being in a 3D game. Using ‘ports’ on the same mesh as the hull creates an issue in resolving where a collider mesh for the hull and a collider mesh for the ports (functioning as a sub-colider for the gun system) ends/begins. Indeed, there are ways to solve this through code, but at the time I figured just using a properly created model would be easier (not so sure about that now…).
“This is actually a bonus for you, because whatever you do nobody can say it’s wrong.”
-Good point.
Here are two shots off all the ships I’m working on in their current states:
sorry if it is for game low poly then UV is probably best bet here!
and I still have to find some good blueprint for metal plates on top
I did find one for the other ship the Monitor
one problem there are only a few pics showing plates !
and also there are many different models version that were built after I guess
so have to pick the right one
