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Lo-res knot OBJs for clothes/prop modelers - First Batch Done
Posted: 04 February 2013 11:24 PM   [ Ignore ]
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First batch available at ShareCG and Renderosity.
Upload was announced in post #40, so check the lead-up to that post for more background.

For one of my ongoing projects I ended up mesh-modeling a simple dual-cord thumb-knot (since I’ve been unable to find any freebie unrestricted use OBJ knots). The attached image is a Poser 6 render of this 208-face model from various angles (with smooth polys, displacement, cable shader, etc applied) - I was gobsmacked that something so simple could look so effective!

Now as anybody who’s tried knows, modelling knots can be a right PITA, so a bunch of freebie, unrestricted use pre-made OBJs that can be imported into whatever you’re modeling seems a good idea. If there’s enough interest I’ll try doing a few more knots (anybody else with a masochistic streak is welcome to join in!)
wink

More info about the one I’ve already done on my blog here - Ideas - a knotty problem. I didn’t think it was really worth uploading as a freebie on its own, but if I can add a few more, maybe some cable ends (eye-loop type things) too?

(Alternatively, if somebody knows where there’s a bunch of free, unrestricted use, lo-res polygon mesh knots please point me at them!)

Thanks to amy_aimei for sparking the thought with her bow-knot freebie at ShareCG…

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Dual_Cord_Thumb_Knot.jpg
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Posted: 05 February 2013 03:25 AM   [ Ignore ]   [ # 1 ]
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I would be interested. Can’t make knots look right so these would be a great help.grin

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Wendy

My website: http://www.wilmapsdigitalcreations.co.uk

Tutorials: http://www.wilmapsdigitalcreations.co.uk/view_products.php?cat=10

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Posted: 05 February 2013 03:59 AM   [ Ignore ]   [ # 2 ]
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I don’t need much encouragement Wendy - one positive reply’s good enough for me!

Second knot done - simply removed one cord from the original knot and fiddled a bit to get a reasonable single cord overhand knot (not a thumb knot, which is what I always called it). 152 vertices/144 faces for this one. Blender screenshot attached. SubD works beautifully on the two knots I’ve done (at least in Blender using Catmull-Clark multires, and in Poser using Smooth Polys on the render settings).

Regarding the models themselves - I assume that the eight vertex cylinder I’ve used so far as a basis for the cord(s) is okay as a starting point for you?

Any specific knots you’re interested in? A straightforward bow/shoelace knot (like Amy’s) would be an obvious one to start with I guess. And I remember a fair bit about knots from my time in the cubs/scouts, though a lot of my recollections are rather frayed and need splicing!

No promises, but I’m rather enjoying this and while my enthusiam’s going it would be good to focus on knots that people actually want!

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Posted: 05 February 2013 04:12 AM   [ Ignore ]   [ # 3 ]
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“the eight vertex cylinder I’ve used so far as a basis for the cord(s) is okay as a starting point”

That would be fine - gives me something to work from.

Any knots that would be used on clothing really. Those on bows, belts, laces, scarfs etc.

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Wendy

My website: http://www.wilmapsdigitalcreations.co.uk

Tutorials: http://www.wilmapsdigitalcreations.co.uk/view_products.php?cat=10

PLEASE NOTE:
My items are NOT to be used on Second Life website.  They have recently changed their TOS and are legally able to take/steal anything uploaded and resell/redistribute to items.

 

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Posted: 05 February 2013 05:49 AM   [ Ignore ]   [ # 4 ]
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Are you aware of Knot Tyer 3D?

http://www.stevenabbott.co.uk/Knots/knottyer3d.html

It may be helpful. I haven’t delved into it too deeply myself.

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Posted: 05 February 2013 06:37 AM   [ Ignore ]   [ # 5 ]
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I’d already discovered Gordian Knot, but I hadn’t seen KnotTyer3D - thanks Bob, definitely worth a try. (Couldn’t get the ‘pull-through’ working in GordianKnot, but it seems perfect for wrapping cords around objects - I have a few things I’m planning to try using it for, e.g. wrapping a Muay Thai fighter’s arms…)

But I’m still having fun here trying to hand craft really low-poly-count knots using an eight vertex circle as the rope profile. Here’s my first try at a bow (552 vertex/536 faces - and 160 of the vertices are for the two loops)

First attached image is a DAZ Studio 3 screenshot of the imported OBJ (right), and the same imported OBJ with SubD applied (left).
Second image is a DS3 render - the SubD smooths it nicely (the errors in the render are 99.9% certainly my model!)

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BowDS3.jpgbowR.jpg
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Posted: 05 February 2013 06:50 AM   [ Ignore ]   [ # 6 ]
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English Bob - 05 February 2013 05:49 AM

Are you aware of Knot Tyer 3D?

http://www.stevenabbott.co.uk/Knots/knottyer3d.html

It may be helpful. I haven’t delved into it too deeply myself.

Just downloaded it and given it a quick test run.

First impressions are that it produces loose knots (great for showing how they’re tied, but not quite what I’m after), the models aren’t particularly low-poly-count (1,400 for the reef knot), and the only way to save the 3D result is as a POV-ray file - I’m not familiar with that, and can’t find it on Blender’s importlist. [Correction: You CAN save as OBJ!]

Great little program though - now I don’t need to keep those old shoelaces on my desk to help me visualize the knots I’m doing! cheese

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Posted: 05 February 2013 06:53 AM   [ Ignore ]   [ # 7 ]
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I just downloaded that too. You can save as .obj file, but when I loaded that into Silo none of the vertices were welded together. As soon as I applied subdivision it broke apart. Yes they are too loose as well.

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Wendy

My website: http://www.wilmapsdigitalcreations.co.uk

Tutorials: http://www.wilmapsdigitalcreations.co.uk/view_products.php?cat=10

PLEASE NOTE:
My items are NOT to be used on Second Life website.  They have recently changed their TOS and are legally able to take/steal anything uploaded and resell/redistribute to items.

 

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Posted: 05 February 2013 07:06 AM   [ Ignore ]   [ # 8 ]
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My quick test run was obviously a little too quick!

Thanks Wendy! Spotted the ‘Save As OBJ’ now. Okay, loaded the exported bowline OBJ into Blender - looks nice, but a bit loose:
- it’s using an 8-vertex circle rope profile. Great, just what I want.
- There’s loads of duplicate vertices (that’ll be the problem you had). Doing a ‘remove doubles’ in Blender deletes 4240 of the 5664 vertices, leaving 1416.
- Multires/SubD works fine after removing doubles (see attached image), so you need to do the equivalent when you import into Silo.

I have an idea that deleting all except a dozen or so of the key circular-profile edge-loops, and then connecting the remaining ones back together (skinning the edge-loops is Blender’s term for it iirc, not sure about Silo), will give a nice low-poly mesh that’ll be quite easy to tighten up…

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bowline.jpg
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Posted: 05 February 2013 07:20 AM   [ Ignore ]   [ # 9 ]
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That’s it for tonight - I’ll try stripping down and rebuilding the bowline tomorrow.

Thanks Bob, I think you hit on a good’un there!

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Posted: 05 February 2013 07:30 AM   [ Ignore ]   [ # 10 ]
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Cool. I couldn’t get Gordian Knot to run for me at all.

As you say, Knot Tyer is meant to illustrate how to tie knots rather than make them, and although I knew there would be ways round the looseness I hadn’t investigated further.

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Posted: 05 February 2013 10:09 AM   [ Ignore ]   [ # 11 ]
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Yeah, I grabbed KnotTyer, a long time ago and didn’t like the looseness of the knots.  So I didn’t go much further with it…

Welding them removes a bunch of verts and drops them to a much more ‘reasonable’ poly count.  And skinning the edge loops was something I was going to look at today…

With the ‘stranded’/‘twist’ shader…rope, cable and now knots are easy.

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Posted: 05 February 2013 01:28 PM   [ Ignore ]   [ # 12 ]
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What stranded/twist shader?

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Posted: 05 February 2013 08:14 PM   [ Ignore ]   [ # 13 ]
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The one in the Railings02 freebie I recently uploaded. Nothing fancy or clever, just a simple equation based around the sine function… f=abs(sin(50U+5V)) .

Here’s a screenshot of the Poser shader if you just want to do it yourself. There’s a bit more info about ways to do the shader in DS here, and there’s a DAZ Studio version in the freebie too.

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Posted: 05 February 2013 10:16 PM   [ Ignore ]   [ # 14 ]
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After a play around with the bowline I think that KnotTyer3D is a great starting point!

Here’s a first stab at reducing the poly-count of the bowline - 1416 faces in the imported OBJ (after removing doubles), 184 in the pared-to-basics version.

An experienced modeler could probably tighten up the knot quite easily with the imported OBJ, but for the likes of me - the less vertices to keep track of, the better!

This first attempt exposed some easy-to-avoid mistakes, e.g. don’t delete all the unnecessary vertices at once, since it’s easy to lose track of which edge loop connects to which…

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Posted: 05 February 2013 10:47 PM   [ Ignore ]   [ # 15 ]
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That low-poly one is proving quite easy to tighten up by manipulating one edgeloop at a time. It’s mainly a fine-tuning process- select an edgeloop, adjust the view so it’s edge-on, rotate it about its centre,move it a bit, pick another edge loop, etc.

Using loopcut is a no-no for me here since the new loop isn’t circular (or regular octagonal to be precise). If I need another edgeloop I’m finding the best way is to delete the edges that I would have cut, extrude one of the exposed edge loops, then skin the faces between the new edgeloop and the other exposed one.

Here’s the bowline after a little making some corrections and tightening it up a bit. Still not there yet, but it’s proving the principle.

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