Is it to be expected that translating a texture (e.g. T_Col_Marble) to 
extreme values, like 25000, gives results that differ very much from the 
non-translated texture? Even for discontinuities to appear in the 
texture, i.e. sharp boundaries between areas?? Is there a limit one 
should not cross??? I could give examples of what I get...
Thank you old hands for helping me :) 
-- 
Regards,  Sander

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Sander <san### [at] stolscom> wrote:

> Is it to be expected that translating a texture (e.g. T_Col_Marble) to 
> extreme values, like 25000, gives results that differ very much from the 
> non-translated texture? Even for discontinuities to appear in the 
> texture, i.e. sharp boundaries between areas?? Is there a limit one 
> should not cross??? I could give examples of what I get...
> Thank you old hands for helping me :) 

I wouldn't think so, though some textures, such as spiral and wood wouldn't
be very interesting in those extremes.  Do you have examples where this
occurs?

Geoff

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On Wed, 28 Feb 2001 18:12:12 +0100, Sander wrote:
>Is it to be expected that translating a texture (e.g. T_Col_Marble) to 
>extreme values, like 25000, gives results that differ very much from the 
>non-translated texture? Even for discontinuities to appear in the 
>texture, i.e. sharp boundaries between areas?? Is there a limit one 
>should not cross??? I could give examples of what I get...
>Thank you old hands for helping me :) 

Yes, there are some problems in the noise function out that far.  There's no
hard limit, but the quality of the function deteriorates sharply past around
10000 or so.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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Sander wrote:
> 
> Is it to be expected that translating a texture (e.g. T_Col_Marble) to
> extreme values, like 25000, gives results that differ very much from the
> non-translated texture? Even for discontinuities to appear in the
> texture, i.e. sharp boundaries between areas?? Is there a limit one
> should not cross??? I could give examples of what I get...
> Thank you old hands for helping me :)

Yes, this is a known problem with patterns using the noise function in POV <=3.1
See thread "Bug in noise function" in povray.bugreports (dated 25.08.99) for a
short discussion.

-- 
Margus Ramst

Personal e-mail: mar### [at] peakeduee
TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg
Home page http://www.hot.ee/margusrt

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In article <3a9d5546@news.povray.org>, Geoff Wedig says...
> 
> I wouldn't think so, though some textures, such as spiral and wood wouldn't
> be very interesting in those extremes.  Do you have examples where this
> occurs?
> 
> Geoff
> 
I wil put an image in p.b.i. showing part of a cylinder with same 
texture twice: the lower has the texture translated 100x more than the 
upper, and the scale has been 40 in stead of 4 to get anything 
acceptable. The lower shows what I was referring to: the texture seems 
to be discontinuous along sharp vertical boundaries, for one thing. 
There is more amiss, however... 
:(
Ron and Margus: thanks for the explanation! What a luxury to get answers 
so quickly from you people :)  I will simply have to use less 
translation and scaling, I suppose.
-- 
Regards,  Sander

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I was stunned to see a mere 100 times change (and another 40 times making
for 4000) cause an affect so extreme as your example image in p.b.i.
Although it must be to do with the actual large numbers it turns into.  At
some 20 thousand units multiplied by 40 you end up getting a translate
distance around 800,000+ units.  We must always remember POV-Ray works
correctly within certain limits of large and small numbers.  Infinence is
not possible after all.

Bob H.

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In article <3a9ec712$1@news.povray.org>, Bob H. says...
> I was stunned to see a mere 100 times change (and another 40 times making
> for 4000) cause an affect so extreme as your example image in p.b.i.
> Although it must be to do with the actual large numbers it turns into.  At
> some 20 thousand units multiplied by 40 you end up getting a translate
> distance around 800,000+ units.  We must always remember POV-Ray works
> correctly within certain limits of large and small numbers.  Infinence is
> not possible after all.
> 
> Bob H.

I do realize that I should have scaled first and then translate not to 
make things worse than they already are, so to speak: I will try just 
that and I suppose it will be all right. Thank you for all the help,
-- 
Regards,  Sander

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Sander <san### [at] stolscom> wrote:

> In article <3a9d5546@news.povray.org>, Geoff Wedig says...
>> 
>> I wouldn't think so, though some textures, such as spiral and wood wouldn't
>> be very interesting in those extremes.  Do you have examples where this
>> occurs?
>> 
>> Geoff
>> 
> I wil put an image in p.b.i. showing part of a cylinder with same 
> texture twice: the lower has the texture translated 100x more than the 
> upper, and the scale has been 40 in stead of 4 to get anything 
> acceptable. The lower shows what I was referring to: the texture seems 
> to be discontinuous along sharp vertical boundaries, for one thing. 
> There is more amiss, however... 

No need.  I can bow to the people below.  They obviously know more than I
about this.

> Ron and Margus: thanks for the explanation! What a luxury to get answers 
> so quickly from you people :)  I will simply have to use less 
> translation and scaling, I suppose.

Geoff

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In article <3a9ec712$1@news.povray.org>, Bob H. says...
<snip>
> distance around 800,000+ units.  We must always remember POV-Ray works
<snip>

My mistake: what I did was: first scale 40 then translate about 
20.000... Is this the same as first translate 500 then scale 40? I 
really get confused :(

-- 
Regards,  Sander

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