Tile stitching error

[Isomorph]

Tile stitching error

So I am making a crazy project. I want to cover a wall with fractal
tiles to make a giant fractal poster.

Tiles made poster something like these.
http://www.laboratory424.com/project/panel-poster

So each tile I plan on printing on a A4 paper, and I using a very high
resolution to get a photo realistic look. The resolution is 6304x4464. And
the number of tiles in row and column is 8. So that results in 64
tiles.

Now the calculation goes okay, but the stitching of the picture in the end fails and gives an error.

Take a look at the end.

---------- Tile: 61 -------------
Average N = 17,502012, Average DE steps = 68,842074, Missed DE 0,000%       
Done 100,000%, to go = 0h0m0s, elapsed = 1h2m16s, iters/s = 29890253       
Rendering Screen Space Ambient Occlusion. Done 100%         
Image saved: /media/big_store/fraccz00061.tile
---------- Tile: 62 -------------
Average N = 18,068604, Average DE steps = 72,405728, Missed DE 0,002%       
Done 100,000%, to go = 0h0m0s, elapsed = 1h18m47s, iters/s = 30153702       
Rendering Screen Space Ambient Occlusion. Done 100%         
Image saved: /media/big_store/fraccz00062.tile
---------- Tile: 63 -------------
Average N = 18,402285, Average DE steps = 55,895546, Missed DE 0,065%       
Done 100,000%, to go = 0h0m0s, elapsed = 1h30m11s, iters/s = 29537657       
Rendering Screen Space Ambient Occlusion. Done 100%         
Image saved: /media/big_store/fraccz00063.tile
Compiling image from tiles, row 0
Compiling image from tiles, row 1
Compiling image from tiles, row 2
libpng error: Write Error
[write_png_file] Error during writing bytesRendering finished

The resulting corrupt file is 2GB is size, so I think we have hit some
kind of file or memory limit in the stiching process.

Any idea to how I fix this ? Anyone solved a similar problem?

Or is I the first that make fractals at this size?

[taurus]

ok, I'll try to get things sorted. you try to produce 64 tiles @ 6304x4464, so the resulting image should have 50.432 x 35.712 pixels (about 1800 Mpixels). When my calculation is right the raw uncompressed image will have about 5,4 GB (@ 24bit per pixel).
The first thing that comes to my mind is the 4GB limit, some file systems have (FAT32 for example).

My first question would be, what file sytem are you trying to store your image on and has it a file size limit of 4GB?

[Isomorph]

I am using the ext3 file system. en.wikipedia.org/wiki/Ext3
and it doesn't seems to have a 4GB file size limit.

But the resulting png file is 2GB in size and I have 2GB of memory in my computer.

Does the stitching process load all the tiles into the memory?, because then we might have the problem there.

Anyway can I save the tiles as png files and turn off the stitching process?

[taurus]

But the resulting png file is 2GB in size and I have 2GB of memory in my computer.

• it is corrupted, so this is no indicator for enough memory.
• png is a compressed format and I dunno, if libpng first tries to stitch to an uncompressed binary, before compressing it.

All in all it was just an idea and in fact I don't know where this error come from. I seldom tried, but in my two or three attempts it worked fine on win 7 64.

[Madman]

Why 540 dpi? It won't be an improvement over 300 dpi so no reason to go to that resolution. Frankly, I can't see a difference between 200 dpi and 300 dpi (especially if you are going to print wallpapersize), except under a magnifying glass, but I'm sure there are people who'll tell you they can. At 200 dpi, your filesize will be a factor 7 lower. Might be worth a try

[simon.snake]

If the link you provided is an indication of what you're trying to go for, why do you have to stitch them together first? Are you going to put them onto canvas?

[taurus]

why do you have to stitch them together first?

I guess, cause mandelbulber does it automatically - no way to get rid of.

[Isomorph]

Why 540 dpi? It won't be an improvement over 300 dpi so no reason to go to that resolution. Frankly, I can't see a difference between 200 dpi and 300 dpi (especially if you are going to print wallpapersize), except under a magnifying glass, but I'm sure there are people who'll tell you they can. At 200 dpi, your filesize will be a factor 7 lower. Might be worth a try

Why, because it is a crazy project  

I trying to go extreme, because that's where the fun happens. This is where the usual methods/software breaks down and you can learn new things.  And I also want to learn how to make
giant posters and using fractals are so dawn pretty.
  
Now I have experimented with different resolutions, and this is the maximal resolution my printer can do.
I am trying to find a resolution, so that 1 pixel on the printer is 1 pixel in the picture.

I have already printed out pictures in different resolution and compare them side by side. And I can see a differences  in the finer details.
  







 

[Isomorph]

I have modified the source code for mandelbulber so that it generate PNG tiles, very easy. Oh-ray for open source software.