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I try to render a huge image in cycles. It's 16000x8000 pixels. Everything seems to work normally, the 4 CPU cores do their work, but once the final tiles are rendered the image vanishes and I can't save it. What could be the reason for this?

horace
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  • can you add a little bit more details? What hppens when you press Save as Image? If you are using Windows You can toggle the Syste Console in the Window menu and look there for more error messages. – Leon95 Aug 25 '14 at 16:54
  • "save as image" is greyed out. I can't press it. I will look into the console after the next try. It takes about 5 hours to render... – horace Aug 25 '14 at 17:11
  • the message in the console is: calloc returns null: ... hm... but shouldn't 8gb ram be enough for this? the scene is very simple geometry and texture wise. and the image buffer also shouldn't take more than half a gigabyte i think. – horace Aug 25 '14 at 17:21
  • Keep blender open. Im serching in the userpreferences for an filesize limitation. – Leon95 Aug 25 '14 at 17:22
  • By any chance is this your problem? http://blender.stackexchange.com/q/14377/2217 – David Aug 25 '14 at 17:55
  • ok i have rendered an image with this resolution, and canceled the render. if i want to save it, the option save as image was also greyed out. Then blender freezes for a few minutes. after that when blender reacts again, i can click it. but saving this image as .jpg file was too much for my 4GB Working storage and i have to kill blender. I dont know what to do in your case, maybe its not possible with a to small working storage. – Leon95 Aug 25 '14 at 18:09
  • Voted to close because it seems the problem was caused by a lack of memory. – gandalf3 Aug 25 '14 at 21:56

1 Answers1

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I think found the reason.

After the last tiles of the render finish blender suddenly needs a lot of RAM. More than I expected for the image buffer. Maybe because it uses floats and not bytes?

During my earlier tries I had a lot of chrome and firefox tabs open (browsers take so much RAM, incredible! :)) and only 2GB of the RAM were free.

When I rendered again, this time I closed most other applications before the rendering finished. With 5GB of free RAM it worked! :)

horace
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