First, all combinations seem to complete the image ok, the order the image is
worked on is different than the docs seem to sugest.

When using the following .ini file

***
+I "Tennis_court.ini"
Width = 1800
Height = 1029
Bounding_Method = 2 ;bsp
Antialias = On
Sampling_Method = 1
Antialias_Threshold = 0.200
Jitter = Off
Antialias_Depth = 3
Output_To_File = On
Output_File_Type = N
Display = On
Verbose = Off
Quality = 9
;Work_Threads = 3
Render_Pattern = 3
Render_Block_Step = 4
Input_File_Name = Tennis_court.pov
Output_File_Name = P:\Still_images\
Test_Abort = On
Test_Abort_Count = 100
***

Width = 1800
Render_Pattern = 3
Render_Block_Step = 1
completes the line in the center and then goes to the next above/below line

The first block step to offset is 4, thats ok, but does not complete the line
first.

From the docs 3.1.2.8.2.2 Render Block Step
Render_Block_Step = 1 or 2 or 3, should be the same (in this example).
=1 completes the horizontal line first, then moves onto the next.
=2 or 3 completes only half the horizontal line, and comes back to the other
half later.

Is this a feature, or should the docs be made more clear?

On all renders that take more than 2 to 3 hours, I have been using the
Render_Pattern. I'm able to decide if I wan't to keep the picture much sooner.

Stephen S

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Le 18/09/2011 17:15, StephenS a écrit :
> First, all combinations seem to complete the image ok, the order the image is
> worked on is different than the docs seem to sugest.
> 
> When using the following .ini file
> 
> ***
> +I "Tennis_court.ini"
> Width = 1800
> Height = 1029
> Bounding_Method = 2 ;bsp
> Antialias = On
> Sampling_Method = 1
> Antialias_Threshold = 0.200
> Jitter = Off
> Antialias_Depth = 3
> Output_To_File = On
> Output_File_Type = N
> Display = On
> Verbose = Off
> Quality = 9
> ;Work_Threads = 3
> Render_Pattern = 3
> Render_Block_Step = 4
> Input_File_Name = Tennis_court.pov
> Output_File_Name = P:\Still_images\
> Test_Abort = On
> Test_Abort_Count = 100
> ***
> 
> Width = 1800
> Render_Pattern = 3
> Render_Block_Step = 1
> completes the line in the center and then goes to the next above/below line
> 
> The first block step to offset is 4, thats ok, but does not complete the line
> first.
> 
> From the docs 3.1.2.8.2.2 Render Block Step
> Render_Block_Step = 1 or 2 or 3, should be the same (in this example).
> =1 completes the horizontal line first, then moves onto the next.
> =2 or 3 completes only half the horizontal line, and comes back to the other
> half later.
> 
> Is this a feature, or should the docs be made more clear?

Render_Pattern is the order that is followed for a Render_Block_Step of
1. (and even, it's the distribution to the rendering threads
(+WT<number>): if some blocks renders faster and you have many threads,
it is not going to be an absolute displaying order)

Then come in play modulo-arithmetic (also named clock-math): for a total
number of block N (even if only one pixel is needed from that block,
[think bottom right corner of picture with odd width & height]), the
Render_Block_Step S must be pseudo prime with N.(**)

We start at block 0 (as always), and add Render_Block_Step modulo N,
again and again until N blocks have been rendered.


W=1800, H=1029, default block size of 32 (IIRC).
width in block = 57 (round up 1800/32)
Height in block = 33 (round up 1029/32)
N= 57*33 = 1881.

**:
When the render block step is not pseudo prime with N, it is reduced
until it become so (the absolute answer being 1).

Ergo, Render_Block_Step=3 in your case is reduced to 2. Hence the same
behaviour in both case.

You can probably contribute in the discussion page relative to Render
Block Step if you found the current text not clear enough. The best
comments for new users (of any feature) is from new and fresh users of
that feature: they are worded with the expectation of new users in mind,
something old users have long forgotten.

http://wiki.povray.org/content/Documentation:Reference_Section_1.3

As commented by Jim Holsenback (at the bottom of the discussion page),
Size, Pattern and Step are all related together.
If you change the block size (for a given height & width of the final
picture), you will change N, and as a consequence the pseudo-prime
reduction of Step.

> 
> On all renders that take more than 2 to 3 hours, I have been using the
> Render_Pattern. I'm able to decide if I wan't to keep the picture much sooner.
> 

That was the point of render_pattern: the interesting part is not always
on the top line.


-- 
Software is like dirt - it costs time and money to change it and move it
around.

Just because you can't see it, it doesn't weigh anything,
and you can't drill a hole in it and stick a rivet into it doesn't mean
it's free.

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Le_Forgeron <lef### [at] freefr> wrote:
....
> We start at block 0 (as always), and add Render_Block_Step modulo N,
> again and again until N blocks have been rendered.
....
My observation was that the block order seems to follow(in this example)
0,1,3,5 on the left half of center(ok)
and
10,12,14 on right half of center, instead of 2,4,6

I forgot to look at the wiki first, will re-read there and think some more :-)

Stephen S

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