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From: Jörg "Yadgar" Bleimann
Subject: POVEarth still far away...
Date: 15 Jul 2020 13:16:21
Message: <5f0f01a5@news.povray.org>
Hi(gh)!

I looked up texture_list and texture indices... and finally came up with 
a solution, assigning each two adjacent triangles one texture. But... 
long years in a crowded, badly ventilated case took their toll on system 
health. Both under Linux and Windows POV-Ray 3.7 crashed with a memory 
access error when trying to generate a full-resolution mesh2 of the 
Tbilisi square-degree quadrangle, most likely due to chronically 
overheated and thus faulty RAM. I might thoroughly clean my case and its 
innards from dust and then run memtest, but whatever the result, it 
might cost me at least 100 euros... if not much more, depending how much 
of my 24 GiB RAM is damaged. The worst case would be having to buy a 
complete new system... this probably would take me several years of saving!

Reality hurts! If I only could escape from it... building Khyberspace 
entirely in my brain?

See you there,

Yadgar


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From: jr
Subject: Re: POVEarth still far away...
Date: 15 Jul 2020 14:15:01
Message: <web.5f0f0e3793bb714f4d00143e0@news.povray.org>
hi,

=?UTF-8?Q?J=c3=b6rg_=22Yadgar=22_Bleimann?= <yaz### [at] gmxde> wrote:
> Hi(gh)!
>
> ... The worst case would be having to buy a
> complete new system... this probably would take me several years of saving!

surprised by this.  is there no "flourishing" second-hand market for computers
and or components in Germany?  there must be companies replacing equipment "on
schedule", just like with their (fleet) cars.  you just need to find out who are
the re-sellers.


regards, jr.


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From: Jörg "Yadgar" Bleimann
Subject: Re: POVEarth still far away...
Date: 15 Jul 2020 15:36:23
Message: <5f0f2277$1@news.povray.org>
Hi(gh)!

On 15.07.20 16:09, jr wrote:
> hi,
> 
> =?UTF-8?Q?J=c3=b6rg_=22Yadgar=22_Bleimann?= <yaz### [at] gmxde> wrote:
>> Hi(gh)!
>>
>> ... The worst case would be having to buy a
>> complete new system... this probably would take me several years of saving!
> 
> surprised by this.  is there no "flourishing" second-hand market for computers
> and or components in Germ  there must be companies replacing equipment "on
> schedule", just like with their (fleet) cars.  you just need to find out who are
> the re-sellers.
> 
> 
> regards, jr.
> 
any?

Yes, it is... but for doing POVEarth (or even just Khyberspace!) with 
reasonable resources, a system needs to be state-of-the-art, something 
like an AMD Ryzen Threadripper with 256 GiB worth of RAM and harddisk 
storage in the two-digit terabyte range - far beyond my reach, unless I 
break a lotto jackpot!

It's possibly more likely that one day, I find some ready-made pre-war 
Khyberspace (i. e. a virtual Afghanistan) somewhere on the Internet and 
just join it as an ordinary "tourist"...

See you in Khyberspace!

Yadgar


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From: Bald Eagle
Subject: Re: POVEarth still far away...
Date: 15 Jul 2020 17:20:01
Message: <web.5f0f3ab193bb714ffb0b41570@news.povray.org>
=?UTF-8?Q?J=c3=b6rg_=22Yadgar=22_Bleimann?= <yaz### [at] gmxde> wrote:

> Yes, it is... but for doing POVEarth (or even just Khyberspace!) with
> reasonable resources, a system needs to be state-of-the-art, something
> like an AMD Ryzen Threadripper with 256 GiB worth of RAM and harddisk
> storage in the two-digit terabyte range - far beyond my reach, unless I
> break a lotto jackpot!

I think he meant just to buy some more RAM, second-hand.

I used to work for an electronics surplus place, and we could have probably
filled a pallet with memory sticks of every description.
We could have probably filled several pallets with the hard disks.

You can buy new 1TB HDD for ~35 USD (FRN) or 8 TB for $150
Why you'd need that much, I have no idea.


You can check whatever the equivalent of Ebay and Craigslist for computer
listings, look for used or damaged systems at yard sales, flea markets, moving
sales, estate sales - you really just never know what someone is willing to just
give away for a few dollars.


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From: Jörg "Yadgar" Bleimann
Subject: Re: POVEarth still far away...
Date: 31 Jul 2020 15:02:41
Message: <5f243291$1@news.povray.org>
Hi(gh)

(two weeks later...)

Am 15.07.2020 um 19:19 schrieb Bald Eagle:

> I think he meant just to buy some more RAM, second-hand.
>
> I used to work for an electronics surplus place, and we could have probably
> filled a pallet with memory sticks of every description.
> We could have probably filled several pallets with the hard disks.
>
> You can buy new 1TB HDD for ~35 USD (FRN) or 8 TB for $150
> Why you'd need that much, I have no idea.
>
>
> You can check whatever the equivalent of Ebay and Craigslist for computer
> listings, look for used or damaged systems at yard sales, flea markets, moving
> sales, estate sales - you really just never know what someone is willing to just
> give away for a few dollars.
>

Meanwhile, I installed Memtest86+ and run it now since almost nine 
hours... but still no ram error has been found! And I worked out more 
precisely where that memory access error with mesh2writer.pov occurs: 
always in the 22th iteration of the outer part of the last nested loop 
(currently, I don't have the code at hand, as I plan to run Memtest86+ 
until tomorrow morning - I write this message from my old laptop).

If even tomorrow no RAM error would have been found, there would be no 
way but running my test version of mesh2writer.pov (reduced resolution, 
1000 by 1000 rather than the original 3601 by 3601 data points) several 
times with another out of four RAM strips left out each time...

Until then, I'll have some fun with my Commodore 64 recently 
reactivated... time to build a directory for my 150+ diskettes!

See you in Khyberspace!

Yadgar


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From: Jörg "Yadgar" Bleimann
Subject: Re: POVEarth still far away...
Date: 2 Aug 2020 10:54:17
Message: <5f269b59$1@news.povray.org>
Hi(gh)!

I now have run mesh2writer.pov in various RAM configurations including 
only one 4 GB strip or one 8 GB strip in slot 1 - but always I got the 
memory access error in the 22nd outer iteration (at 1000 by 1000 data 
points; the number of the inner iteration varies wildly!) of the last 
nested loop:

#if (!(tilename="n80e014" | tilename="n80e016" | tilename="n80e017"))
   #declare i=0;
   #write (ES, "  texture_list")
   #write (ES, "  {\n")
   #write (ES, concat("    ",str(NumTextures, 1, 0),"\n"))
   #declare a=0;						
   // #declare c=0;
   #while (a<ydim)					// outer loop
     #declare b=0;
     #while (b<xdim)					// inner loop	
       #declare C_Texture = eval_pigment(P_Texture, 
<(0.5+b)*(1/(xdim-1)), (0.5+a)*(1/(ydim-1)), 1>);
       #warning concat("Iteration ", str(a, 1, 0), "-", str(b, 1, 0))
       #write (ES, "    texture\n")
       #write (ES, "    {\n")
       #write (ES, "      pigment\n")
       #write (ES, "      {\n")
       #write (ES, concat("	   color rgb <",vstr(3, C_Texture, ",", 1, 
7),">\n"))
       #write (ES, "      }\n")
       #write (ES  "	 finish{ F_Earthslice }\n")
       #write (ES, "    }\n"
       // #declare c=c+1;
       #declare b=b+1;
     #end
     #declare a=a+1;
   #end
   #write (ES, "  }\n")
#end

// end of code

I just can't figure out what should be wrong with this code - or is it 
just a bug in POV-Ray 3.7?

See you in Khyberspace!

Yadgar


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From: Bald Eagle
Subject: Re: POVEarth still far away...
Date: 2 Aug 2020 12:05:00
Message: <web.5f26ab9093bb714f1f9dae300@news.povray.org>
Yadgar Bleimann wrote:

> always I got the
> memory access error in the 22nd outer iteration (at 1000 by 1000 data
> points; the number of the inner iteration varies wildly!) of the last
> nested loop:

The fact that you're getting a very reproducible error in a highly specific
point in the code, tells me that the problem isn't with your RAM, it's with
either the input to your code, or a calculation in your code, which _might_ (or
might not) be triggering a bug of some sort.

by "the 22nd outer iteration ... of the last nested loop", I prsume that you
mean when a = 21?

>    #while (a<ydim)     // outer loop

Here it looks to me that you have a calculation that then gets passed to a
function that operates on image data.  I just have the feeling that this is the
line that triggers the error.   Have you tried commenting that out and running
the code to see if it completes?
If it does, then I would look at the values very carefully, and maybe play some
games like "#(if a = 21)..."
But first I'd also send your values to the #debug stream and perhaps a log file.
Look at the image in P_Texture.  What size is it?  Have you spreadsheeted out
your x, y values to see if they make sense?   What happens at a = 21?
Why is z = 1 instead of 0?
Have you tried using a different image file or running it through a different
piece of software to see if it changes anything? (just give the brightness or
contrast a slight tweak to change the image and save a new version).

>        #declare C_Texture = eval_pigment(P_Texture,
> <(0.5+b)*(1/(xdim-1)), (0.5+a)*(1/(ydim-1)), 1>);

I see that you have this finish statement in _every line_.

>        #write (ES  "  finish{ F_Earthslice }\n")

Why not just define that as the default finish and leave it out?


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From: Jörg "Yadgar" Bleimann
Subject: Re: POVEarth still far away...
Date: 2 Aug 2020 14:03:44
Message: <5f26c7c0$1@news.povray.org>
Hi(gh)!

On 02.08.20 14:03, Bald Eagle wrote:

> by "the 22nd outer iteration ... of the last nested loop", I prsume that you
> mean when a = 21?

Technically, it's the 23rd iteration, i. e. when a=22!
I now scaled the original 3601 by 3601 heightfield down to 1000 x 1000 
(instead of just using 1000 x 1000 eval_pigment() tracing points on the 
original heightfield) using GIMP and no interpolation(!) - and got 
exactly the same result: memory access error at a=22!

Then I took a close look at the pixels in that row (as the lines are 
processed in ascending order, this is line 977 (999-22) in the GIMP 
display) - and found nothing suspicious, the first pixel in that line is 
rgb <74, 230, 0>, which should calculate to something like
rgb <0.290196078, 0.901960784, 0> in eval_pigm().

> 
>>     #while (a<ydim)     // outer loop
> 
> Here it looks to me that you have a calculation that then gets passed to a
> function that operates on image data.  I just have the feeling that this is the
> line that triggers the error.   Have you tried commenting that out and running
> the code to see if it completes?

I tried this (and used a uniform color, rgb <0.5, 0.5, 0.5>)... before, 
I also discovered another flaw in the code, res was still set to 3601... 
I corrected this to 1000, which did not change anything.

But now with the uniform color, it's even more absurd: the loop breaks, 
but no longer consistently at a=22, but during the first run at a=19, 
during the second once more at a=22, during the third run at a=20...

> But first I'd also send your values to the #debug stream and perhaps a log file.

How do I do this?

See you in Khyberspace!

Yadgar


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From: Bald Eagle
Subject: Re: POVEarth still far away...
Date: 2 Aug 2020 14:20:01
Message: <web.5f26cb3593bb714f1f9dae300@news.povray.org>
=?UTF-8?Q?J=c3=b6rg_=22Yadgar=22_Bleimann?= <yaz### [at] gmxde> wrote:

> But now with the uniform color, it's even more absurd: the loop breaks,
> but no longer consistently at a=22, but during the first run at a=19,
> during the second once more at a=22, during the third run at a=20...

Hmm.   That's pretty weird.
What's your OS & povray version?
Have you tried running a different version or changing the #version statement at
the top of the file?

What about using #for instead of #while ?
Stepping through the values by 2's ?
If you can post an easy-to-follow version (indents, some comments) of your full
code in the text file section, maybe I can spot something.


> > But first I'd also send your values to the #debug stream and perhaps a log file.
>
> How do I do this?

You already know how to do:
#write (ES, concat("    color rgb <",vstr(3, C_Texture, ",", 1,
7),">\n"))

So just add a line with
#debug concat("    color rgb <",vstr(3, C_Texture, ",", 1,
7),">\n")


in your command line, you can just add Debug_File=LoopCrash.txt
so that you have something like
+w1024 +h768 +A0.3 Debug_File=LoopCrash.txt

Then everything that goes to the debug stream will go to the file as well.
http://www.povray.org/documentation/view/3.6.1/222/


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From: jr
Subject: Re: POVEarth still far away...
Date: 2 Aug 2020 14:25:00
Message: <web.5f26cc4993bb714f4d00143e0@news.povray.org>
hi,

=?UTF-8?Q?J=c3=b6rg_=22Yadgar=22_Bleimann?= <yaz### [at] gmxde> wrote:
> Hi(gh)!
> On 02.08.20 14:03, Bald Eagle wrote:
> ...
> > But first I'd also send your values to the #debug stream and perhaps a log file.
>
> How do I do this?

there's an option for that.
"All_File=true
Echo all debug, fatal, render, statistic, and warning text to ALLTEXT.OUT"
<http://wiki.povray.org/content/Reference:Text_Output_Options#Directing_Text_Streams_to_Files>

alternatively, on Linux, you can do something like:

  $ povray myini 2> mylog

to capture all povray's text output.


regards, jr.


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