I am wondering what people really think about how normals and scaling should
work.  If you're interested in this topic, please see this page and take the
'surface normal survey'.  You can reply by emailing me or reply to this
post.

http://nathan.kopp.com/normals.htm

-Nathan

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Nathan Kopp wrote:
> 
> I am wondering what people really think about how normals and scaling should
> work.  If you're interested in this topic, please see this page and take the
> 'surface normal survey'.  You can reply by emailing me or reply to this
> post.
> 
> http://nathan.kopp.com/normals.htm
> 
> -Nathan

Question 1: answer A

Question 2: answer B

Question 3: answer A

Question 4: good question... it doesn't matter to me provided it's
clearly documented

Question 5: answer B

Question 6: same as question 4

	To summarize, I think that when you scale the object to which the
normal is applied, you should scale the whole normal (size of pattern
and bump depth), when you only scale the normal, it doesn't matter
provided it's clearly documented.

		Jerome
-- 
*******************************

* they'll tell you what can't * mailto:ber### [at] inamecom
* be done and why...          * http://www.enst.fr/~jberger
* Then do it.                 *
*******************************

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Nathan Kopp wrote:
> 
> I am wondering what people really think about how normals and scaling should
> work.  If you're interested in this topic, please see this page and take the
> 'surface normal survey'.  You can reply by emailing me or reply to this
> post.
> 
> http://nathan.kopp.com/normals.htm
> 
> -Nathan

1.) A
2.) B
3.) B
4.) B
5.) B
6.) B


Rational for some of the answers -

If you glue sand to the surface of a box, like the one used in your examples,
as you scale the x & z directions the sand will be further apart but the
relative height of the roughness on the surface will remain unchanged. Since
we are talking surfaces here, if you glued sand to a thicker box, all you
would have is sand with the same granular size on a larger box. It's surface
roughness would remain unchanged. Therefore it is important to remember that
scaling an object should not change the surface normals depth. It may change
the slope and scale of the pattern but not it's physical depth.


-- 
Wishing you Seasons Greetings, A Merry Christmas, and A Happy New Year !
Ken Tyler -  1200+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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No answers here, but an idea: can't you just add some more keywords so the user
can have all the possibilites? Especially the one where the normal depth is
flattened depending how you scale the object.

Nathan Kopp wrote:

> I am wondering what people really think about how normals and scaling should
> work.  If you're interested in this topic, please see this page and take the
> 'surface normal survey'.  You can reply by emailing me or reply to this
> post.
>
> http://nathan.kopp.com/normals.htm
>
> -Nathan

--
Samuel Benge

E-Mail: STB### [at] aolcom

Visit the still unfinished isosurface tutorial: http://members.aol.com/stbenge

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Ken <tyl### [at] pacbellnet> wrote ...
>
> 1.) A
> 2.) B
> 3.) B
> 4.) B
> 5.) B
> 6.) B
>

I understand your rationale but I wonder why you chose A for 1 and B for 2
and 3.  To be consistent, I would think that if 2 and 3 were B, then 1
should be B also.

-Nathan

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Ken wrote:
> 
> If you glue sand to the surface of a box, like the one used in your examples,
> as you scale the x & z directions the sand will be further apart but the
> relative height of the roughness on the surface will remain unchanged. Since
> we are talking surfaces here, if you glued sand to a thicker box, all you
> would have is sand with the same granular size on a larger box. It's surface
> roughness would remain unchanged. Therefore it is important to remember that
> scaling an object should not change the surface normals depth. It may change
> the slope and scale of the pattern but not it's physical depth.
> 
	I understand you reasoning, but I have to disagree: it has happened
several times to me that I had to scale my whole scene (otherwise some
parts of an object made in sPatch were so small that they disappeared (I
don't mean that they were too small to be seen, more like they were
optimized away...). In such a case, the normal depth should follow the
general scaling. It's the same thing as when you see a map at several
scales: the fact that the scale changes doesn't change the relative size
of the terrain features (and shouldn't).
	The reasoning you present here is the reason why I am undecided for
questions 4 and 6 (and I should have said the same thing for question 5
now that I think about it...)

		Jerome
-- 
*******************************

* they'll tell you what can't * mailto:ber### [at] inamecom
* be done and why...          * http://www.enst.fr/~jberger
* Then do it.                 *
*******************************

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SamuelT. <STB### [at] aolcom> wrote...
> No answers here, but an idea: can't you just add some more keywords so the
user
> can have all the possibilites? Especially the one where the normal depth
is
> flattened depending how you scale the object.
>

I am trying to find a way to do this.

My personal preference is: A,B,A,A,B,A
The rule here is: scaling ALWAYS affects depth.
I have found a way to implement this.

My close second choice is: B,B,B,B,B,B
The rule here is: scaling NEVER affects depth.
I have not yet found a way to implement this perfectly, but I'm looking.
<< Ohhh... brainstorm... I just thought of something that I'll have to try.
:-) >>

My third choice is: A,B,A,B,B,B
The rule here is: scaling the object ALWAYS affects depth
and scaling the normal NEVER affects depth.
This could be quite difficult to implement.  Please don't say you want it to
act this way.

What does the official version do?
Patterns such as waves/bumps: B,B,B,B,B,B
Patterns such as waves/bumps within normal_map: B,B,B,B,B,B
Patterns such as granite/bozo: B,B,B,B,B,B
Patterns such as granite/bozo within normal_map: A,A,B,A,A,B

( see a trend?  maybe keeping b,b,b,b,b,b would be good now that I look at
it this way... )

-Nathan

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Nathan Kopp <Nat### [at] Koppcom> wrote...
> 
> What does the official version do?
> Patterns such as waves/bumps: B,B,B,B,B,B
> Patterns such as waves/bumps within normal_map: B,B,B,B,B,B
> Patterns such as granite/bozo: B,B,B,B,B,B
> Patterns such as granite/bozo within normal_map: A,A,B,A,A,B
> 
I take that back.

That should be:

Official version:
Patterns such as waves/bumps: A,A,B,A,A,B
Patterns such as waves/bumps within normal_map: A,A,B,A,A,B
Patterns such as granite/bozo: B,B,B,B,B,B
Patterns such as granite/bozo within normal_map: A,A,B,A,A,B

-Nathan

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Nathan Kopp wrote:
> 
> Ken <tyl### [at] pacbellnet> wrote ...
> >
> > 1.) A
> > 2.) B
> > 3.) B
> > 4.) B
> > 5.) B
> > 6.) B
> >
> 
> I understand your rationale but I wonder why you chose A for 1 and B for 2
> and 3.  To be consistent, I would think that if 2 and 3 were B, then 1
> should be B also.
> 
> -Nathan

I was undecided about A and shot from the hip with my answer. For most
of my answers I was influenced by the images and the functions they
represented.

-- 
Wishing you Seasons Greetings, A Merry Christmas, and A Happy New Year !

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My answers:

1) A
2) B
3) A
4) A
5) B
6) A

Reasoning:  Take a heightfield.  Paste it onto the object.  Scale the
object.  A normal applied to an object should act like this.

Mark

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