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Hi.  I'm new.  I barely know what I'm doing.  But I'm having a really great time.   :D

So I have this cliché box-box-foldintpow thing going.  And I'm just crazy pleased with it all.  Really want to make a stupid huge image to print.

The aspect ratio is 2:3, and I want a 30"x45" print at 300dpi.  So 9000x13,500.  I figure I'll let the Big render utility handle the aa upscaling, but I'll do the downscaling myself in 'Shop, because I gotta assemble it anyway (and maybe color correct it before downscaling or whatever).

Only thing is, no matter how I split up the tiling, from as low as 30 or so tiles to as high as 100, on either my pc or my mac, I can't get the tiles to save correctly.

...they render just fine.  Look perfect in the render view.  Like super mcultra happy about that.  But the png that's written is black.  So is the bmp.  Or jpg.

Z buffer totally comes through, though (if I have it toggled to save).  No problems there.  Which is weird.

So here's the kicker:  It only seems to happen if the TOTAL dimensions are close to a gigapixel in size.  Like 27000x40500 (aa 3x) won't save no matter how I split up the tiling.  And If I turn the total size down to 25800x38700 (998mp) it still won't save.

BUT, if I turn it to 25700x38550?  Now only 990 megapixels?  Then the images are written correctly (same color I see on the screen instead of just solid black) and the whole thing renders fine.

Um. Yea.  Anyway, I saw the other posts where people have done 1gp+ renders.  So I didn't know if this should go in the bug section or if I'm just missing something really obvious and stupid.  Please advise.

Thanks.  :)

Sooo...  I'm not positive, but I think it has to do with the Ambient Shadows?  They seem to stop working correctly at that size.

The SSAO options all give me this error:

Could not build wavelet levels,
no ambient shadow calced.
Error in ambient shadow
calculation. Stopped.

And the DEAO is solid black.  Which I guess is probably why all my renders are solid black.

Does anyone know how to avoid this?

So... it's totally the ambient shadows.  At least I'm pretty sure.  Mostly.

I tested it on a blank scene with a generic intgpow and I still got the black occlusion output at near gigapixel res with the big render.

But when turned down to 990 megapixels it starts working again.  Only thing I changed was the total size.

I have not done a Big Render and wondered what that was ... this post implies someone did a 3GB http://www.fractalforums.com/mandelbulb-3d/big-render/ ?

try canceling the ambient shadows and render one square of your big image. Look if it is better

Oh.  For sure.  It's definitely a function of the ambient shadows at a size greater than ~995mp.

You can easily test it with any scene, any formulas:

- Set the resolution to 25800x38700.  Render the ambient shadow pass.  Turns the geo black.

- Set the resolution to 25700x38550.  Render the ambient shadow pass.  Occlusion renders fine.

i tested in that size and it is black, if you increase the light intensity it change you can see some details, maybe you can play a liitle with it. Are you sure you need a so big imagen?, I use to make some big images, The bigger is 15000 x 11000 pixeles and it does not had that problem, and i can do a very big image of about the wide of the printer(1 m), the owner of the printer said it is more than enough to make a high quality printing.

I use only 7 rays y decreased to 0.1 MaxL on DEAO ambient shadow