PC is hard-locking when rendering semi-large-ish resolution images

[ChrisBruin]

As the title states, when I am rendering images that are a bit large, like over 1500x1500 pixels, my machine hard-locks and I need to force power it off. I tried leaving it sit throughout a work day, and when I returned home, it was still frozen.

I have tried following this tutorial, https://docs.chaosgroup.com/display/...y+Large+Images, to render large images, but I can't even render a 2k image. I am aiming to have my final render be a 4k image.


The attached image is about all I can max out in terms of resolution, 600x1000px.
The attached settings image is what I use most of the time, but it fails currently at that set resolution, or anything higher. I did have the settings matched with the ones from the tutorial linked above, but the same result happens, my PC completely freezes.

There is an exception though, when I hide the head, I am able to render at larger resolutions (2k+). This is most likely due to the complexity of the head displacement setup, I have various regions of the face displacement driven by a series of masks with tiling displacement maps. These maps are absolutely necessary to providing a realistic result for the skin, since skin is made up of many micro surface structures. The micro tiling displacement maps as well as the masks that drive the regions are all 1024x1024 or under. You can see my displacement shader below. If I remove the microtiling displacement maps, the skin does not look like skin any longer, and looks like a smooth wax head (awful!). You can see a closeup of the head here: https://www.dropbox.com/s/5vt6cxcm1y...ace3K.png?dl=0 I still can't render at a resolution that I am trying to achieve though.

Any idea how I can overcome this render hurdle? I'm basically blocked from working on the boy right now, since I can't completely see how the body will look in full context with the head at a decent enough resolution where I can make out any details.

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Geometry:
Around 600k tris in the scene
Displacement maps on everything
Without Xgen hair

Texturing/Materials:
32 UDIMs
Around 10 materials for everything
Average texture resolution is 4096x4096, for closer shots. Can mip down for distant shots, but would prefer to keep everything sharp for the larger shots I intend.

Lighting
- 1 dome with HDR
- 1 area light

PC hardware:
i7 8700k @ 4.6GHz
32GB RAM

Software Info:
Maya 2018.3
V- Ray Next hotfix 2, v4.04.03.00010 (feb 25 2019)

[Zdravko.Keremidchiev]

Apparently, this resolution is too big for your machine, and the memory can't handle it. A few things that come to mind will be to try using Bucket mode instead of progressive since it is a lot more memory optimized. Another thing is you have caustics on. This can increase memory usage a lot and produce a very little effect, especially when you don't have water or any refractive material in the scene. Another thing that eats up RAM memory is the edge length of the displacement if you bump it up a little (in example 1) and you get good enough result you can make the rendering much lighter. If that doesn't help you can render the scene on stripes and compose them together later in post-production.
Furthermore, you can check this forum thread for memory optimization as well: https://forums.chaosgroup.com/forum/...usage-in-v-ray