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From:
Subject: wrong report about max_gradient
Date: 19 Nov 2001 03:22:16
Message: <5tfhvt4uj921171obes8j1hfl93eoi64ei@4ax.com>
POV 3.5 b 7 on PII 233 128 MB with NT 4 Sp 6

I had such syntax within isosurface:

  max_gradient 10
  evaluate 1, 10, 0.99

but renderer said after trace

  Warning: The maximum gradient found was 184.775, but max_gradient of
  the isosurface was set to 1988.679. Adjust max_gradient to
  get a faster rendering of the isosurface.

IMO 1988.679 <> 10. Expected behaviour, misunderstand or bug ?

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35


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From: Warp
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 04:37:16
Message: <3bf8d2cc@news.povray.org>
I think this is something which has been fixed for the next beta. You should
wait for it and see if the problem still exists.

-- 
#macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
],13),8)-3,10>#end blob{N(array[6]{11117333955,
7382340,3358,3900569407,970,4254934330},0)}//                     - Warp -


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From: R  Suzuki
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 05:29:42
Message: <3bf8df16$1@news.povray.org>
See  http://news.povray.org/3be10cf9@news.povray.org
>**** Dynamic maximum gradient estimation *****
>max_gradient G_max
>"eval(uate) P0, P1, P2"
>where
>  P0 is the minimum max_gradient value in the estimation process,
>  P1 should be more than 1 (over-estimation parameter), and
>  P2 should be less than 1 (attenuation parameter).
>
>The max_gradient, G_max, is re-calculated for each ray as following
>        If (G_max< G*P1)
>             then   G_max = G*P1*P1
>             else if (G_max>P0) then G_max = G_max*P2,

So, the max_gradient value in the scene file is the 'initial' value
and it is re-declared in the estimation (or rendering) process.



> Warning: The maximum gradient found was 184.775, but max_gradient of
> the isosurface was set to 1988.679. Adjust max_gradient to
> get a faster rendering of the isosurface.

I think only the sentense "Warning: The maximum gradient found was 184.775."
 is enough for the evaluatation result.

R. Suzuki


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From:
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 05:35:06
Message: <lunhvt07a7gg1ffmln18bmq6pvug3ftn88@4ax.com>
On Mon, 19 Nov 2001 19:29:39 +0900, "R. Suzuki" <r-s### [at] aistgojp> wrote:
> I think only the sentense "Warning: The maximum gradient found was 184.775."
> is enough for the evaluatation result.

I can't agree. When there are more then one isosurfaces simetimes initial value
is only way to recognize where founded value shuold be applied.

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35


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From: Thorsten Froehlich
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 06:37:43
Message: <3bf8ef07@news.povray.org>

Skiba <abx### [at] babilonorg>  wrote:

> POV 3.5 b 7 on PII 233 128 MB with NT 4 Sp 6
>
> I had such syntax within isosurface:
>
>   max_gradient 10
>   evaluate 1, 10, 0.99
>
> but renderer said after trace
>
>   Warning: The maximum gradient found was 184.775, but max_gradient of
>   the isosurface was set to 1988.679. Adjust max_gradient to
>   get a faster rendering of the isosurface.
>
> IMO 1988.679 <> 10. Expected behaviour, misunderstand or bug ?

See

From: "JRG" <jrg### [at] hotmailcom>
Newsgroups: povray.beta-test
Subject: Isosurfaces *much* slower in beta 7?
Date: Tue, 30 Oct 2001 23:07:31 +0100
Message-ID: <3bdf24b3$1@news.povray.org>
Xref: news.povray.org povray.beta-test:2475



____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From: Thorsten Froehlich
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 06:41:54
Message: <3bf8f002@news.povray.org>
In article <3bf8df16$1@news.povray.org> , "R. Suzuki" <r-s### [at] aistgojp>
wrote:

>> Warning: The maximum gradient found was 184.775, but max_gradient of
>> the isosurface was set to 1988.679. Adjust max_gradient to
>> get a faster rendering of the isosurface.
>
> I think only the sentense "Warning: The maximum gradient found was 184.775."
>  is enough for the evaluatation result.

The problem is that many people don't read the documentation and then
complain about "holes and other bugs" with isosurfaces (see several messages
in these groups).  I would also prefer a shorter message, but as long as
many people who use a free software cannot be asked to read the
documentation before reporting something as a bug this message is a
inconvenience that has to be forced upon all users :-(

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From:
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 07:21:54
Message: <k0uhvt4l9ppp8pgs655obeirbedjovd74n@4ax.com>
On Mon, 19 Nov 2001 12:37:42 +0100, "Thorsten Froehlich" <tho### [at] trfde>
wrote:
> > IMO 1988.679 <> 10. Expected behaviour, misunderstand or bug ?
>
> See
>
> From: "JRG" <jrg### [at] hotmailcom>
> Newsgroups: povray.beta-test
> Subject: Isosurfaces *much* slower in beta 7?
> Date: Tue, 30 Oct 2001 23:07:31 +0100
> Message-ID: <3bdf24b3$1@news.povray.org>
> Xref: news.povray.org povray.beta-test:2475

I don't like bothering but there is nothing about difference between typed value
and outputed value. in that thread :-(
Perhaps it was misunderstand but I reported here that I wrote 10 in script but
report message said I wrote 1988.679. I know meaning of the message. It is
annoing when you are trying find isosurface from many isosurfaces to apply
calculated value.

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35


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From:
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 07:28:02
Message: <8duhvto4s52070im27o3fkomaif4cms34e@4ax.com>
On Mon, 19 Nov 2001 12:41:53 +0100, "Thorsten Froehlich" <tho### [at] trfde>
wrote:
> The problem is that many people don't read the documentation and then
> complain about "holes and other bugs" with isosurfaces.

IMO you misunderstand this bug report. I wrote 10 but report said I wrote more
than 1900. I understand inner behaviour, I just pointed out is says false.

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35


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From: Thorsten Froehlich
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 08:01:41
Message: <3bf902b5@news.povray.org>

Skiba <abx### [at] babilonorg>  wrote:

>> The problem is that many people don't read the documentation and then
>> complain about "holes and other bugs" with isosurfaces.
>
> IMO you misunderstand this bug report. I wrote 10 but report said I wrote more
> than 1900. I understand inner behaviour, I just pointed out is says false.

I was not refering to you or the bug report at all.  I was only pointing out
the need for the additional parts of the message that appear unnecessary for
those who did read the documentation.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From: Thorsten Froehlich
Subject: Re: wrong report about max_gradient
Date: 19 Nov 2001 08:05:40
Message: <3bf903a4@news.povray.org>

Skiba <abx### [at] babilonorg>  wrote:

> I don't like bothering but there is nothing about difference between typed
> value and outputed value. in that thread :-(
> Perhaps it was misunderstand but I reported here that I wrote 10 in script but
> report message said I wrote 1988.679. I know meaning of the message. It is
> annoing when you are trying find isosurface from many isosurfaces to apply
> calculated value.

Here it is:

>From: "Thorsten Froehlich" <tho### [at] trfde>
>Newsgroups: povray.beta-test
>Subject: Re: Isosurfaces *much* slower in beta 7?
>Date: Mit, 31. Okt 2001 10:27 Uhr
>Message-ID: <3bdfc402@news.povray.org>
>Xref: news.povray.org povray.beta-test:2503
>
>> That's really sad, i was just starting to use it intensively.
>
> That is part of beta testing.  It is not really a serious problem, it is
> just very slow...
>
>> Apart from
>> being incredibly slow it also seems to produce wrong results.
>
> No, it only changes your max_gradient.  The reported found maximum gradient
> value is still correct.

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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