3DS Max - UVing complex objects

Flatlander Woman

Hi everyone,

I am pretty new to modeling and UVing in 3DS Max and I'm having some trouble making proper UVs and lightmap UVs. Basically, I am building a modular outdoor railing piece. It's composed of two basic parts - the railing handlebar, and a railing post piece, which is instance repeated 10 times. Here's what the untextured version looks like.



My plan is to UV the handlerail of the balustrade, then UV one of the rail post. Each of the other rail posts is instanced so they should update. After that, I'll attach them all into one editable poly, rescale them down, and pack them. However, UVing the railing post is giving me trouble.



Being a noob, I'm somewhat at a loss as to how to approach UVing this piece. I can't simply planar map each of the four sides, because there are some parallel faces (examples highlighted on the right) which would be reduced to lines & lost entirely in the UVs. I'm also having trouble efficiently selecting faces, as the angles of the piece are such that Planar Angle doesn't give me the results I want.

How would you go about UVing this piece? Bearing in mind that, for lightmap UVs, I will need to fit in ten separate unwrapped versions of it so they don't overlap, so ideally the base UVs would be pretty simple.

Any help would be much appreciated. Thanks!

ZacD

I'd unwrap it similar to a cylinder, there will be some stretching, but that will be fine.

Flatlander Woman

Hi Zac,

Thanks for the advice. The problem that I'm having with planar & cylindrical unwraps is that they don't work for the surfaces that are facing straight up and down, like in the right half of the screenshot. Since they're perfectly parallel with the ground, cylindrical wrappings just turn those faces into lines, which don't work for UVing. You can see the problem areas highlighted in red in the screenshot below - those lines are actually faces.



The only thing I can think of is to break them off and do a planar Z-mapping to create a little UV ring. But, while that will probably work for the diffuse UVs, which let me overlap, it will be a nightmare for the lightmap UVs, which can't overlap. Since it will produce 8 rings x 10 rail posts = 80 individual clusters on the lightmap UVs!

ZacD

You can move the uv's around after you unwrap, post the obj and I'll show you how I'd unwrap it.

Sam Hatami

what zacd said + you need to relax the uvws to get the z faced uvs to flatten out a bit and then straighten selection.

Under the UVW Dialog menu : Tools ->Relax -> Relax by Face Angles (set Amount to 1).


Go into face selection mode, select the entire element, hit the straighten selection button under your "Reshape elements" group (the rollouts to the right).

ZacD

I got bored waiting.

Download OBJ: https://drive.google.com/file/d/0B7m3EkWf1vh6cGxweGdJc2RGTjg/edit?usp=sharing

Flatlander Woman

Ack! Although I greatly appreciate all your help, somehow I'm still ending up in a rut.

@Sam: When I relax the UVs, I end up getting some very strange results. This is what my UVs end up looking like at each of the three steps - first the initial cylindrical mapping, then relaxing by face angles, and then straightening the selection.




Clearly I've done something wrong somewhere, but I'm just not sure what it is...

I'm going to get this file on a google drive and upload it, if people care to take a look at what I've been doing. The shape of the rail post has changed a bit since my first post, but the general problems are the same.

https://drive.google.com/file/d/0B8Fj9G98rFEsVTUyU1hxcXpuWnM/edit?usp=sharing

Mark Dygert

1) Before you relax or straighten there are a lot of edges along the side that need to be welded. As soon as you do a cylinder unwrap, select all of the verts and weld them with a really low threshold.

2) Try relaxing by edge angles.

Flatlander Woman

Oof. Sadly, nothing has availed me so far. This is what I get after welding & using relax by edge angles:



I suppose I could manually rescale each Z-aligned UV for now... but there must be a better workflow. That approach would be untenable on a sufficiently complex object.

In general I'm not sure what Straighten Selection is supposed to do. I would imagine that it aligns UV edge loops nicely, but every time I've used it it has produced wacky results like in the screenshot. Does anyone know what the cause of that might be?

ZacD

I don't use 3ds so I cannot be much of a help, but a relaxed result should look something like the uv on the left half of this example, I personally use 3dcoat to unwrap models and get it to that point. Then I use softimage to manual edit uvs to straighten them. I don't know of a tool to straight all of the edges, so I do it line by line.

Flatlander Woman

I see. Thanks for the help Zac!

Just so I can be super clear on how to close this out: assuming I'm *not* using Relax and want to do this manually (since Relax seems to be unpredictable in this case), how would I go about flattening these Z-faced UVs, while still keeping them as part of the same UV island? I can't seem to scale or rotate them - is Relax the only way to achieve this effect?

huffer

You could go in top view, select all faces from one side, planar map them, relax, repeat for the other 3 sides. Then select the edge loops or verts at the border of the four uv islands, flatten them, then stitch with the next ones.

akaChris

hi guys,

I have to admit I am a bit skeptical about doing it the way described above as it produces a lot of warping. That usually happens when normalizing a trapezoid poly for example to a rectangle. (as can be seen with the checker texture warping above)

I`d suggest an alternative approach (both are surely valid for different reasons):

> since your model seems perfectly symmetrical, take advantage of that fact. delete all but one side of rail posts. that should leave you with the polys of one side plus the chamfer border (just on one side).

1 > open the unwrap, select everything (3, ctrl+a) and choose mapping>flatten (turn of rotate). (it is also possible to do this other ways like by projecting along an axis and relaxing). Flattening will make sure that there is almost zero bending in each face.

2 > Once flattened you will get a lot of single pieces. pick the top piece for example and select its bottom edge(2). choose stitch selected from the menu (don't use a shortcut - minor max annoyance - one of many). in the menu that opens up you need to set the bias from 0.5 to 0 (that way all stitched elements will use the scaling of the previous).

3 > now select the next piece's bottom edge and continue the same way stitching (now you can use a shortcut for stitching as that massively speeds up the workflow).

you should end up with a perfectly clean unwrap with no warping (the chamfer border might be wonky and will need aligning to to main geometry (this might be avoidable using project and relax instead of step 2 and 3).

That means the outer shape of your rail posts uv should more or less match the silhouette of the obeject itself. it should not be straight lines vertically.

4 > now copy the mesh and rotate to fill up the missing sides

5 > if you don't want to save uv space you can now open the unwrap again, turn on select by element and move the sides you want to be unique horizontally next to each other (if they are exactly horizontally aligned it will later be easiert when doing manual texture work in PS.

(HINT: it might suffice to just have two sides different and 2 sides looking the same. so 2 stacks of uv basically as from any angle only two sides can be seen at a time and with 90 degrees of rotation you might get away with that)

hope that helped as an alternative solution.

PS: would be great if anyone could tell me that my method is stupid and inefficient, as I`m always desperately trying to find better/faster ways of unwrapping (I HATE UNWRAPPING )

cheers,
Chris

Mark Dygert

Thanks for posting the file, I took a look and I think I found out why it was misbehaving, it should have unwrapped pretty much just like ZacD was explaining but there where some problems with the geometry.

These triangles are going to cause all kinds of problems, continue the beveled edge all the way up. I'm not sure why you tried to collapse the polys there? If it was to save a few polys, the polys it saved where not worth it to any modern engine and certainly going to slow down your workflow. These triangles are also what is throwing off the relax and the straighten.



This is after I continued the bevel through the choke point.




This is after running straighten. Triangles and stragithen NEVER get a long... NEVER.

ZacD

I went ahead with the straightened example because Flatlander Woman needed lightmap uvs as well. Warping is a bit less important in light maps, multiple posts will fit better on a single lightmap, and they can't be tiling.

The straightened UVs can work fine for the main UVs as well, depending on what you want. Tiling textures will work better if your textures are like this, hand painting and overlaying photos for textures is easier too. Of course you should overlay and tile uvs when you can, but I'd keep a post unique on all 4 sides and rotate and mirror the geometry of the duplicated posts, and have all the posts stack on the uvs. That way you get variation and save UV space.

Those advantages are subjective though and there's no one best option.

akaChris

agreed, there is a significant difference between what you would want for lightmaps to avoid light seams. hopefully in the future game engines will require less and less of that manual labor

Flatlander Woman

YES! Thank you so much, Mark! After correcting that geometry the Relax command works as expected. I'm not exactly sure how the geo ended up as it did - it looks like I chamfered that edge which created the triangles at the corners, and then accidentally deleted a connecting edge at some point.

Thanks very much for your help, everyone. This has taught me a lot!

AFsoft

hi, i did this like below : 

there is no stretching in this method, and the islands are optimized.