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 CAD / Ray-Tracing / 2055
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Subject: 
Re: LPub/LSynth/Mega-POV Question
Newsgroups: 
lugnet.cad.ray
Date: 
Wed, 7 Jan 2004 03:51:34 GMT
Viewed: 
1665 times
  
In lugnet.cad.ray, Larry Pieniazek wrote:
In lugnet.cad.ray, David Perdue wrote:
Hello,

Larry is right.  The cross sections are not overlapping as they are supposed to.

This can happen if the wire is bent too hard, or the constraints are too far
apart.  LPub uses a large fixed size array when synthesizing between any two
constraints.  If the length between the constraints is larger than the sum of
the cross sectional parts, you get spacing.

Kevin


I’m doing some rendering for Building Instructions, and am coming across a
little problem that I am not quite sure how to resolve. Here is the big picture:
I am doing extremely high quality BI’s, using LPub, which means that the
resolution is very large. Two of the features I added are LSynth generated parts
(mainly electrical wires -- these are MindStorms BI’s) and outlining of the
renderings using Mega-POV.

However, the problem is, there are little tiny (VERY tiny) “spaces” in between
certain sections of the bendable electrical wires generated with LSynth; they
are not all throughout the wires, just in a section here and there. Whether they
are there because the wires aren’t set up correctly, or they are there because
that is the way they are generated I don’t know. From a resolution of 800x600,
they are practically invisible and don’t cause any problems. From, say, a
1200x1500 resolution, they are still invisible once the rendered image gets
squeezed down, but the image is so large dimension-wise to start with, that
Mega-POV catches these little “cracks” and fills them in with bright white
spots. Even when the final image is squeezed down, these white spots are
visible; although not horrendous, they can be noticed if the image is
scrutinized long enough. I simply cannot be having these white specks in my
images.

Does anybody have any suggestions? Is there any way to fix this, or will I just
have to redo the electrical cables very carefully until all the cracks go away?
The latter scenario does not seem a pleasant one and I'm not sure if it is the
best solution. I have tried messing around with the Mega-POV options in LPub,
but no success so far.

Any help would be greatly appreciated.

Synthesised wire and tubing, if I recall correctly, is achieved by placing a
large number of "primitive" elements along the spline that defines the
centerline of the desired shape, aligned so they are tangential to the spline at
that point, and spaced out so that they just overlap each other. The tiny spaces
you see are presumably where they don't quite overlap.

This is just a wild guess but are the gaps where the wires bend more, or on
sections where the wires are straighter?

One possible hack is to replace the wire primitive used with one that is just
slightly longer so that when it's pieced together it overlaps the next piece
more.

That's just a guess, but it may be easier to do that than to adjust the
interelement spacing (that is used within the code to decide where to place the
elements on the spline) to make the elements a bit closer together,

Kevin would know for sure, I'm just guessing. But I hope it was of some help.



Message is in Reply To:
  Re: LPub/LSynth/Mega-POV Question
 
(...) Synthesised wire and tubing, if I recall correctly, is achieved by placing a large number of "primitive" elements along the spline that defines the centerline of the desired shape, aligned so they are tangential to the spline at that point, (...) (21 years ago, 6-Jan-04, to lugnet.cad.ray)

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