Subject:
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Re: Advice on hair pieces
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Newsgroups:
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lugnet.cad.dat.parts
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Date:
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Thu, 16 Sep 2010 19:09:02 GMT
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Viewed:
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23498 times
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In lugnet.cad.dat.parts, Lee Gaiteri wrote:
> I've moved on to looking at part 62696, "Minifig Hair Ponytail with Long Bangs"
> (x1930 on Peeron), and I found the part needs a lot of cleanup. (So does 30475,
> which surprisingly has received no cleanup at all desipte its submission to the
> tracker.) I turned the hair around because it faced the wrong way, and changed
> the origin slightly because it was in a weird place. There are a lot of coplanar
> quads, which I believe are not the fault of the original design but rather of
> the stl2dat converter's bizarre use of 4 significant figures instead of strictly
> going out to 4 decimal places, which has introduced a number of rounding errors.
Actually original parts only have triangles and have been merged by stl2dat (the
4th batch used a different concerter and no triangle to quad merge is done).
That said, I had a look at m62696, there are only 5 non-coplanar quads, all
within the 3° tolerance (see http://www.ldraw.org/Article512.html#coplanar).
This can be checked with LDDP 2.04
(http://sourceforge.net/projects/lddp/files/), with Planarcheck
(www.philohome.com/isecalc/planarcheck.htm) or with Datheader
(http://mikeheide2.kilu.de/index.php?page=datheader).
> To my knowledge getting the original file and re-converting isn't feasible, so
> I'm looking into what it will take to write a utility that tries to adjust the
> vertices to restore coplanarity.
Interesting idea. A radical method is to split offending quads into triangles,
this can be done automatically with Planarcheck or Datheader.
>
> However, the biggest problem I've run into is something I'll need some advice
> with. In the part, the interior of the hair piece is 25 LDU in diameter. This is
> a problem because the minifig head is 26 LDU in width. Scaling this up by a
> factor of 1.04 is not an option because by my measurements, the exterior of the
> part seems correct; the height is 61.94 LDU, which translates to roughly 24.77mm
> give or take a bit; that agrees with my measurement of slightly over 24.5. So
> scaling up would add roughly another mm to the height which is wrong.
You could only grow in horizontal direction. Going from 24.5 to 25ldu means only
a 2% size increase, I don't think it could be noticed.
>
> Since this is my first cleanup of a hair piece, I'm not sure what best practice
> would be. My instinct says to push out the interior vertices by a 0.5 radius
> from center so that collision with the head is impossible. Is this the best
> approach, or is there something other part authors have done as more standard
> practice?
I have sometimes carved a bigger hole (using Intersector,
http://www.philohome.com/isecalc/intersector.htm), but that's a big job.
>
> Also on this part I noticed the interior of the real piece has a sort of split
> ring, slightly raised, around the stud hole, and this in turn means I'd probably
> also have to raise up the interior top of the piece by 1 LDU. I assume accuracy
> in this section is not considered so important that I need to replicate the
> split ring and can use regular ring, edge, and cylinder primitives, but feedback
> on this would be appreciated.
I have done a primitive for that:
http://www.ldraw.org/cgi-bin/ptdetail.cgi?f=p/stud4p.dat
Philo
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Message has 2 Replies:
 | | Re: Advice on hair pieces
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| (...) I noticed the 4th-batch part I worked on had a significantly better format. That must be why. It was missing some edge lines, but Edger took care of that handily. (...) Heh, I would've thought my idea of a utility was more radical. I'm not (...) (14 years ago, 17-Sep-10, to lugnet.cad.dat.parts)
| | | Re: Advice on hair pieces [DAT]
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| (...) is inset a little way and this stud only juts out by 1 or 2 LDU at most. I find I can get a reasonable facsimile of the interior by using this set of primitives: 1 16 0 0 0 13 0 0 0 1 0 0 0 13 4-4edge.dat 1 16 0 0 0 1 0 0 0 -1 0 0 0 1 (...) (14 years ago, 25-Sep-10, to lugnet.cad.dat.parts)
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Message is in Reply To:
| | Advice on hair pieces
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| I've moved on to looking at part 62696, "Minifig Hair Ponytail with Long Bangs" (x1930 on Peeron), and I found the part needs a lot of cleanup. (So does 30475, which surprisingly has received no cleanup at all desipte its submission to the tracker.) (...) (14 years ago, 16-Sep-10, to lugnet.cad.dat.parts)
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