How to know why a scene use 36 GB of Ram ?

Elor

Hello,

The scene in question is the last picture I posted on my Daz gallery:

The items used are linked on the gallery itself, but here's a recap:

• Arianna 8.1,the HD Addon and the dress are from her Fairytale Bundle.
• the hair is the dForce Fringe Benefit Hair
• the environnement is DM's Moon Circle
• the lightning is done with an HDRI from Skies of Economies, the free version, and a spotlight behind Arianna's hairs.
• the jewellery is a freebie from @ioonrxoon, found here.

My computer is a Macbook Pro with a 10 cores M1 Pro with 32 GB of unified RAM (I don't remember the number of GPU cores, but it sit iddle so…) and I'm using the last available Daz version (no beta) and I have not updated to the recently released Mac OS Sonoma.

The dress and the hair are simulated with dForce. I modified the pose of the dress a bit after the simulation was done, because I wanted the dress to fly a bit above the ground but I think that's about it from a 'technical' point of view.

I was surprised to see how long Daz needed to start to render, around 90 seconds, which is three times what I usually see when I'm using a 8.1 figure.

I have no idea if needing so much RAM had a negative impact on rendering performance (the close-up took 8 hours to render, the other picture took less than an hour and half): I don't have an NVIDIA GPU, which means I'm always rendering on CPU and my Macbook Pro M1 has 32 GB of unified RAM (and doesn't seem to mind to much when I ask for more than 32 GB as long as the memory needed is not more than the free space available on the internal SSD), so I mostly want to know for curiosity sake.

I tried to render without the environnement visible, with the HDRI dome hidden, but RAM usage was still peaking at around 36-37 GB. I also tried to use Camera Cutaway from Riversoft Art, but it didn't seem to have an impact on RAM usage. And, wether I was rendering the close-up shown on this message or the wider-pane shoot visible on the gallery, the RAM usage was at a similar high level.

I tried to render the caracter alone (without clothes or hairs) in a newly created scene (after closing and opening Daz), because my previous tests made me though it could be the most likely culprit, but wether with or without the HD addon activated (I loaded her as Arianna 8.1 or Arianna 8.1 HD to be sure I didn't missed something: it's the first time I have a DO 8.1 character with an HD-Addon), the RAM usage felt normal (as in, around 10 to 12 GB shared between the GPU and CPU).

I have Scene Optimizer, so I tried to use it, but Daz crashed while Scene Optimizer was reducing textures so I didn't try longer to use it

If anyone has an idea, I'm all ears

felis

The 2 main factors in RAM consuming is geometry and textures.

I wouldn't think DM's products should stress that much.

Strandbased hair can be a killer in geometry. And always be careful with subD. You can see the geometry of each object in the scene tab. Click on an object and there is an info section below which lists the amount of geometry. If it is closed you can hoover over the middle of the divider line, and when turns yellow click and it will open.

PerttiA

Don't actually know how it works on MAC, but it's not that unusual to hit 32GB's of RAM usage on PC when rendering Iray on GPU, if the rendering drops to CPU, the RAM usage may even exceed 64GB's of installed RAM.

Elor

Thank you for your answers

felis said:

Strandbased hair can be a killer in geometry.

I didn't know that, but I did a couple of tests and, wow .

• With the hair, the render started after more than 90 seconds and RAM usage peaked over 36 GB
• Deleting the hair, the render started after 30 seconds and RAM usage peaked at 12.59 GB. 
• Using a similar looking hair (WF Flora Hair), starting time stays around 30s and RAM usage is around 14.5 GB.

I don't have 8 hours to see if the close-up render is faster but I'll be weary of using this kind of hairs in the futur (even if the result looks great).

PerttiA said:

Don't actually know how it works on MAC, but it's not that unusual to hit 32GB's of RAM usage on PC when rendering Iray on GPU, if the rendering drops to CPU, the RAM usage may even exceed 64GB's of installed RAM.

I suppose it works exactly the same as someone doing CPU rendering on Windows but I just never went this high before with what I thought as a simple scene (a figure, a dress and an room). I had a couple of scenes taking close to 30GB, but it was with multiples G9 figures and more going on in the viewport but as I'm limited to CPU rendering, I'm usually don't go overboard with what I'm doing because I have yet to find a way to prevent DAZ from using every CPU cores, so doing something else while a render is going is painfully slow.

memcneil70

Remember MacBook Pro M1's go directly to RAM. I have one, so you don't render on GPU. I haven't had a render yet hit an 8 hour mark yet though.

For strand based hair, check out https://www.daz3d.com/line-zero-dforce-strand-hair-shaders and see if that will reduce your RAM impact. I keep Scene Info up on my MBP to check on hairs and scenes.

Mary

felis

memcneil70 said:

For strand based hair, check out https://www.daz3d.com/line-zero-dforce-strand-hair-shaders and see if that will reduce your RAM impact. I keep Scene Info up on my MBP to check on hairs and scenes.

Mary

It should reduce VRAM/RAM usage with around a factor 3, because it set tesselation to 0.