The file I'm working on was 1.7 Mb before baking textures onto most of the objects in it and adding a background HDRI, and now it is 17.2 Mb. That's even though all those images are separate files and none are packed into the blender file. Is there a way to determine what is taking the space, and to trim it down?

The above file contains one object not in the comparison file, but that can't explain much of the size difference. The comparison file otherwise is almost identical, even has a few small bits and pieces that have geometry that was pared away in the above version. There were a couple of subsurf modifiers that were applied, but they were extensively optimized. The total vert count is only about 70,000 higher.

  • $\begingroup$ I think that's probably the texture cache on the system RAM. If you are creating textures directly in blender then mind you, there is no compression of any sort. Thus reducing the size of the blend depends on the size of the external files mostly. Even if you don't pack them, those textures would still fill up your ram occasionally. $\endgroup$ – Retrax Feb 16 '18 at 17:19
  • $\begingroup$ An 10mb video file would take up more than 300mb or even 500mb if you load it up into the blender VSE because every single frame is stored directly in the RAM. $\endgroup$ – Retrax Feb 16 '18 at 17:21
  • $\begingroup$ @Retrax But this is the file itself, not its size when it's open. $\endgroup$ – kim holder Feb 16 '18 at 17:24
  • $\begingroup$ adding the HDRI to the file makes its size bigger $\endgroup$ – whyn0t Feb 16 '18 at 17:35
  • $\begingroup$ @whyn0t it references the external file for that, it isn't part of the blender file. $\endgroup$ – kim holder Feb 16 '18 at 17:39

First, you can make sure no textures or external data is accidentally packed into Blender by using the File > External Data > Unpack All Into Files function.

Second, Blender keeps orphaned datablocks around until the next time you save the Blender file. So Save the file, close it. And reopen it, doing it a few times can clear any deleted datablocks from the file.

You can also use the File > Save As > Enable Compression setting to make sure the blend file is compressed to save some space. For files larger than a hundred MB, it will take a bit longer to save and open.

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  • $\begingroup$ Unpack All Into Files - good tip. But, it said there was nothing to unpack. And i've already spent some time trying to ensure there are no unnecessary data-blocks around. It's a mystery. $\endgroup$ – kim holder Feb 16 '18 at 18:48
  • $\begingroup$ Can you share the blend file? I'd love to dig around. $\endgroup$ – Mike Pan Feb 16 '18 at 19:13
  • $\begingroup$ I guess i will - though it's a little large :P $\endgroup$ – kim holder Feb 16 '18 at 19:17
  • $\begingroup$ So the file doesn't seem to have any hidden data that I can see which can cause the file size issue. Frankly I think 17MB for a 800k scene with nearly 300 objects and 160 materials isn't too bad. I can't explain why the file was only 1MB before, but is it possible you appended in some assets (rather than linking) which could cause the file to grow a lot bigger? $\endgroup$ – Mike Pan Feb 16 '18 at 20:36
  • $\begingroup$ Let me also append the file that is almost the same, but without the textures baked on or the HDRI added. $\endgroup$ – kim holder Feb 16 '18 at 20:38

You can try enabling this option in the user preferences. Or manually compress the blend file like Mike said.

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  • $\begingroup$ This is a fair point, but my issue is that i can't understand why it increased in size by a factor of 10 in the first place. This file is going to go in a repository, i don't want 16 Mb of unnecessary stuff in it. $\endgroup$ – kim holder Feb 16 '18 at 19:10
  • $\begingroup$ Hmm..did you render your scene by any chance ? Is the render result still in the memory ? The obvious guesses are that there are orphaned datablocks, like Mike said, and there could be packed textures. It's really hard to tell. $\endgroup$ – Retrax Feb 16 '18 at 19:13
  • $\begingroup$ I did, a few times. But it has been opened and closed since. I checked, and there is no image left for Render Image. I removed all users and closed and opened anyhow - there is no detectable change in the file size. $\endgroup$ – kim holder Feb 16 '18 at 19:27

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