Your message
To: [email protected]
Subject: [Spam Detected] Re: [Opensg-users] search for hidden polygons
Sent: Wed, 4 May 2005 17:29:43 +1000
did not reach the following recipient(s):
c=AU;a= ;p=DSTO;o=SA1;dda:[EMAIL PROTECTED]; on Wed, 4 May 2005 17:30:07 +1000
The recipient name is not recognized
The MTS-ID of the original message is: c=au;a=
;p=dsto;l=EDNEX5010505040730J84NN8CM
MSEXCH:IMS:DSTO:SA1:EDNEX501 0 (000C05A6) Unknown Recipient
--- Begin Message ---
[email protected] schrieb am 03.05.05 18:17:32:
Hi Andi,
On Tue, 2005-05-03 at 15:53 +0200, =?iso-8859-1?Q? Andreas=20Br=FCning ?
= wrote:
> Hello,
>
> I work for one month with OpenSG and i have an interessting problem. I
> load vrml- modells and try to find the polygons, which are completly
> inside the model. I want to create a new Geometry without these
> polygons.
Doing that precisely is pretty tricky...
> My idea is to go in circles around the model and shoot with the ray-
> method from IntersectAction into the center, to find the first
> polygon, which is seen in different directions. In a second step i
> find the polygons around the identified polygon.
OK, that's a common approach to approximating it.
> All this works, but it is too slow. Only o! ne single ray needs nearly
> 250ms. When i shoot about 5000 rays to the model, it takes to much
> time.
>
> My question is: Is there an! y other method, which works faster, or
> has anyone another idea, how i could find out the hidden polygons.
What people usually do is color the units that you want to exclude
(objects or polygons) with unique colors, render, read back the
framebuffer and just look at the pixels. If there are no pixels of the
given color the part is invisible from that view.
It's just an approximation, so depending on how many and what size holes
you have in your model the result can be very inaccurate, but there are
commercial systems that do this kind of thing relatively successfully.
HIH
Dirk
_____________________________________________________________
Thanks Dirk,
that's a nice idea. But is it faster? I don't have special viewports, the user
can look at the mode! l from every site. I search for the poygons, which are
kompletly invis ible. I only load a model and show it. Now I try to take less
rays and find the neighbors of the neighbors of the founded visible polygon.
(and so on...) It's a very tricky problem. May be there is a good combination.
Andi
<http://img.web.de/p.gif>
Verschicken Sie romantische, coole und witzige Bilder per SMS!
Jetzt bei WEB.DE FreeMail: <http://f.web.de/?mc=021193>
http://f.web.de/?mc=021193
------------------------------------------------------- This SF.Net email is
sponsored by: NEC IT Guy Games. Get your fingers limbered up and give it your
best shot. 4 great events, 4 opportunities to win big! Highest score wins.NEC
IT Guy Games. Play to win an NEC 61 plasma display. Visit
http://www.necitguy.com/?r=20 _______________________________________________
Opensg-users mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/opensg-users
--- End Message ---
