POV-Ray : Newsgroups : povray.binaries.images : Help needed with Hamapatch - helmet.jpg (0/1) Server Time
16 Aug 2024 08:12:50 EDT (-0400)
  Help needed with Hamapatch - helmet.jpg (0/1) (Message 1 to 8 of 8)  
From: Jet Jaguar
Subject: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 9 Mar 2002 16:11:29
Message: <cauk8uk7io9tqkffsj77p97699u84kpmrj@4ax.com>
I'm just starting using Hamapatch, and I need some help.  I'm trying
to make a motorcycle-style helmet, and in the area around the face
opening I'm getting what I call "pinching".  The control points seem
to be smooth in Hamapatch, but in the previews and tests I've done, it
appears the surface is pinched together, or there are creases where
the CP's appear smooth.

I've done some research to figure out how to fix this, but everything
I've read says this is just an artifact of the OpenGL preview and it
won't render that way.  But this is clearly not the case because I
still see the pinching in the test renders I've done with POV-Ray.
Any advice how to go about fixing this, or perhaps something I can
tweak in Moray?  I've already noticed I can reduce the effect by
increasing the U and V steps and setting flatness to 0, but this
doesn't eliminate the problem completely.

In the picture attached, the left image is a snapshot of the helmet in
Hamapatch, with the trouble areas indicated by orange arrows.  The
picture on the right shows a test render.  The helmet was exported to
Moray using the sPatch Moray export plugin, a white plastic-like
material was applied, then rendered with POV-Ray 3.1g.  It is not
caused by the export process because I still get the pinching when I
render directly from Hamapatch.

Thanks in advance for your help.

---
Bob Chmilnitzky (a.k.a. Jet Jaguar)
I have a spam blocking address.  Replying to me is like pulling teeth.
Visit my crappy home page at http://home.att.net/~chmilnir/
MSTie #54297

Crossposting makes Baby Jesus cry.


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From: Jet Jaguar
Subject: Help needed with Hamapatch - helmet.jpg (1/1)
Date: 9 Mar 2002 16:11:39
Message: <4kuk8usol004drc297m3b9dlebr6mvnedm@4ax.com>


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Preview of image 'helmet.jpg'
helmet.jpg


 

From: JRG
Subject: Re: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 9 Mar 2002 16:16:33
Message: <3c8a7bb1@news.povray.org>
Just try to avoid three points patches, whenever possible.

--
Jonathan.


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From: Mahalis
Subject: Re: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 9 Mar 2002 16:40:22
Message: <3c8a8146$1@news.povray.org>
It looks to me like those are four-points patches, just with one of the four
in between the other two edge points.

"JRG" <jrg### [at] hotmailcom> wrote in message
news:3c8a7bb1@news.povray.org...
> Just try to avoid three points patches, whenever possible.
>
> --
> Jonathan.
>
>


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From: Jet Jaguar
Subject: Re: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 9 Mar 2002 17:19:04
Message: <fa2l8us6f0ttp283at5d51m43j7tjiv7va@4ax.com>
Yes, they are all four-point patches.  Is it their nearly-triangular
shape that's causing problems?

On Sat, 9 Mar 2002 16:40:16 -0500, "Mahalis" <don### [at] fakeycom>
said:

>It looks to me like those are four-points patches, just with one of the four
>in between the other two edge points.
>
>"JRG" <jrg### [at] hotmailcom> wrote in message
>news:3c8a7bb1@news.povray.org...
>> Just try to avoid three points patches, whenever possible.
>>
>> --
>> Jonathan.
>>
>>
>


---
Bob Chmilnitzky (a.k.a. Jet Jaguar)
I have a spam blocking address.  Replying to me is like pulling teeth.
Visit my crappy home page at http://home.att.net/~chmilnir/
MSTie #54297

Crossposting makes Baby Jesus cry.


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From: JRG
Subject: Re: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 9 Mar 2002 17:42:43
Message: <3c8a8fe3@news.povray.org>
The main problem is that five curves meet at the edge point of those
in-fact-triangular patches. Which causes the artifact.

Here's a possible solution: delete those two crossing splines and the two 'floating'
points (you may need to weld points and re-build some curves):

--
Jonathan.


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Attachments:
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Preview of image 'helmet.jpg'
helmet.jpg


 

From: Txemi Jendrix
Subject: Re: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 9 Mar 2002 18:09:16
Message: <3c8a961c@news.povray.org>

mensaje news:cauk8uk7io9tqkffsj77p97699u84kpmrj@4ax.com...
> I'm just starting using Hamapatch, and I need some help.  I'm trying
> to make a motorcycle-style helmet, and in the area around the face
> opening I'm getting what I call "pinching".  The control points seem
> to be smooth in Hamapatch, but in the previews and tests I've done, it
> appears the surface is pinched together, or there are creases where
> the CP's appear smooth.

JRG has given you the right solution.
Anyway, I 've done a little and quick experiment, inserting a circle (8
points), extruding it several times and moving some control points.
I usually do the modelling in hamapatch this way.
I send you the hamapatch file to p.b.s-f. (9Kb) if you want to take a look
at the model (and use it if you like, still need the interior, but you can
duplicate the model, scale it a bit down, and finish it connecting the
needed points).
Hope this helps.

P.S. here is a render from hamapatch with povray 3.1g
--
Txemi Jendrix
tji### [at] euskalnetnet
http://www.geocities.com/txemijendrix


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Attachments:
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Preview of image 'helmet.jpg'
helmet.jpg


 

From: Jet Jaguar
Subject: Re: Help needed with Hamapatch - helmet.jpg (0/1)
Date: 10 Mar 2002 18:02:20
Message: <cmnn8ukabmka7njuh75cm3dco66e8049gv@4ax.com>
Thanks for the help!  I modified the patch (see attached pic) and
everything looks good now.  You learn something new everyday, and
today I learned:

-  Not only should the patches have 4 points, they should also be
more-or-less rectangular in shape.
-  No more than 4 curves should meet at any one point.
-  There is a kind of kangaroo that lives in trees.  (Not related to
Hamapatch, but I thought it was interesting anyway. :-) 

---
Bob Chmilnitzky (a.k.a. Jet Jaguar)
I have a spam blocking address.  Replying to me is like pulling teeth.
Visit my crappy home page at http://home.att.net/~chmilnir/
MSTie #54297

Crossposting makes Baby Jesus cry.


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Attachments:
Download 'helmet.jpg' (12 KB)

Preview of image 'helmet.jpg'
helmet.jpg


 

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