UV problem

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Hi, I'm working on a cardboard box which will have a flat-packed design applied. (Packaging Design)

I've approached this by applying UV to surface, folding it and extruding. In general, it all works except for stretched/distorted UV on the (outside) folds. I know why it's happening but I'm unsure of the best approach to fix it. I'd appreciate any help/tips.

I've made a sample scene and attached a hip file.

Rob

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UV_Problem.jpg (172.9 KB)
UV_Problem.hiplc (158.8 KB)

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Try applying the UVs right after the grid, before you modify it. The resulting operations should modify those UVs correctly.

Attachments:
uv_stretch.png (249.7 KB)

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Hi, thanks for your help. I know a new feature was added that is supposed to update UVs on models based on grid, box etc but I'm using an imported illustrator eps. (Then using boolean to add folds) The grid was just for the sample but it doesn't seem to work in either scenario.

Your screenshot looks okay at first glance but if you offset the UV to show a letter/number on the fold, you'll see the problem is still there. (It's just not as visible when stretching the straight lines of the squares).

I've attached an updated screenshot and hip file.

thanks
Rob

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UV_Problem_v2.hiplc (160.2 KB)
UV_Problem_v2.jpg (168.3 KB)

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You can drop down a UV edit and adjust the UV spacing till it matches your requirements.

Split your viewport into two views. Then press SPACE-5 in one of the views to bring up a side-by-side workspace for UV editing.
Edited by Enivob - Dec. 15, 2017 16:35:45

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uvedit.gif (1.6 MB)

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Yeh, that is an option but I was hoping there would something less labour intensive than manually editing all the folds. (I have a lot of folds & more divisions than this sample)

Maybe by creating groups from the folds that have horizontal and vertical groups, stretching from their center (so in your gif, it would have the same result as selecting all those edges and scale horizontally). I'm not sure of the best way to set that up though.

Another option would be UV smooth which I thought would be suitable for this but I just couldn't get it to work. (user error)

Thanks for your help
Rob
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You may want to revisit your construction approach. Instead of using a grid try using a line, which can contain the U portion of the UV along it's length, then skin that with a profile. But bevel may still end up being the problem unless you can integrate the bevel you need into the profile shape.
Edited by Enivob - Dec. 16, 2017 17:04:08
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The grid is just for this sample, I'm not using a grid for the actual project. The template for the design is an illustrator file and the grid is the closest option I could think of to represent the design template. The general idea is as follows…

1. Import supplied design template eps file.
2. Convert to Polygons (so I can use boolean)
3. Use boolean to add folds. (using grids, surface/surface, subtract)
4. Use edit/transform to fold into box.
5. Extrude
6. Export for texturing and scale design/print template to UV

In short, I need to keep the UV silhouette as close as possible to the design template.

I'm not sure I understand how using a line would fit into this scenario but am willing to try. Can you explain in further detail?

I've tried another option (attached) which fixes the folds but doesn't work elsewhere so maybe there is an option that blends between the two?

thanks
Rob

Attachments:
UV_Problem_v3.hiplc (164.9 KB)
UV_Problem_v3.jpg (160.4 KB)

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Check out Matt's post on UVs and the sweep SOP.
http://www.tokeru.com/cgwiki/index.php?title=Houdini#Get_correct_uvs_with_a_sweep_sop [www.tokeru.com]

The image shows some crude editing of Matt's file. Try plugging in your logo shape where the circle is located in the network.

If you must use bevel, add it to the shape before it is swept, not to the result of the sweep.
Edited by Enivob - Dec. 17, 2017 09:43:41

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Untitled-1.jpg (171.0 KB)

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I'm not sure I've been clear enough with the description of my problem as I'm not working on a logo.

I've attached a screenshot of the project to help clarify what I'm actually doing. I can't supply scene files or the actual packaging design but I can show the basic idea.

The illustrator eps is the template for the packaging design graphic which will be supplied by a graphic designer. The end result should have a UV silhouette that matches (or is very close to) the template. It all currently works except for this issue with the folds.

Are you saying that the Matt's method would work with this scenario? If so, I'll try to figure it out because at a quick glance, I'm not quite understanding how it would.

thanks
Rob

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UV_Problem_Flatpack.jpg (275.1 KB)

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It looks good to me as is.

Sometimes you have to weigh budget against perfection. Tell the designer not to place any design elements on the seam. I don't think a print shop even allows elements on folds for production items. If a solid color is stretched on the seam it does not matter.
Edited by Enivob - Dec. 17, 2017 13:04:34
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It looks okay at that size because it's much smaller than it will be used. The final renders will be high res and some will be close-ups.

The object that goes inside the box is modelled/textured in extremely high detail and part of the brief is to continue with that level of detail. I've attached a cropped example of the sort of size it will be used at. (The texturing isn't complete as I stopped when I noticed this issue)

I thought there would be a simple method to fix this but it doesn't seem there is so I'll probably try reversing the extrude/problem. Hopefully, squashed inside folds will look better than stretched outside folds.

thanks
Rob

Attachments:
UV_Problem_Crop.jpg (37.5 KB)

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For anyone interested, this is what I've decided to go for. Instead of repositioning the folds and adjusting the template to allow for reversed extrusion I did the following.

Change original extrusion to before bevel and Extrude Outside only, reverse, bevel and Extrude Inside, Outside, Edges.

Hip file and screenshot attached.

Rob

Attachments:
UV_Problem_v4.jpg (175.0 KB)
UV_Problem_v4.hiplc (164.5 KB)

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