Photorealistic rendering seems unreasonably slow and memory hungry

[Anonymous]

I'm using ArchiCAD 22 with the most recent update and trying to create some renders, but I keep running into 'out of memory' errors or render times in the order of several days.

I'm working on a particular scene for one of our architects, he uses an iMac with a 4 core processor and 32GB RAM. I launched the render on his machine on Thursday evening and it didn't finish until Monday morning, roughly 100 hours. Admittedly he chose a resolution of roughly 5000x3000 but it finished eventually.

I tried to run the same render on my computer with a 16 core processor and 16GB of RAM but it consistently failed with the out of memory error. I tried dropping to 3840x2160 but still no dice - the render would only complete at a maximum resolution of 1920x1080. I've tried adjusting the memory usage slider, it seems to make no difference.

So, I bought an extra 16GB of RAM for my machine bringing it up to 32GB total, and relaunched a render at 3840x2160. This time, it failed faster, complaining it had run out of memory, and the Cinerender plugin also crashed.

So, what am I doing wrong? Why does this render at 5000x3000 complete successfully (but slowly) on a Mac with 32GB RAM, but won't complete on Windows at 3840x2160 with 32GB RAM? How much memory do I need to complete a 3840x2160 render? Why does ArchiCAD try to use more memory than the system has available? It seems like a pretty basic problem. A 4K render is not particularly extreme these days, and this is a fairly powerful machine.

edit: for the 4K render, render quality and shadow quality are on low. At 1920x1080 the render took just over a minute.

[Anonymous]

Mac vs PC : Mac OS is a Unix based OS and can use virtual memory up to the full capacity of the hard disks on the computer (but virtual memory can be 1000 time slower than RAM) hence the Mac finished the render slowly, Windows virtual memory however will only double the amount of RAM (again slowly) this is why the Mac finished and the PC did not.

16 or 32 Gb of RAM is not much memory for 3D visualisation, the artist that has been producing some graphics for one of my offices projects has 256Gb RAM in his workstation and the render farm he uses has more than 2000Gb RAM

To reduce your memory usage you will need to look at surfaces definitions, what channels are being used, amount of reflections, transparency, bump, displacement etc etc and also the rendering settings.

Sorry not much of an answer but 3D visualisation really is a ‘trip down the rabbit hole’

Scott

[Erwin Edel]

Is this a 'final presentation' type render, or something you will be producing a lot?

We render most of our impressions at 300 dpi 195x135 mm. This still prints out fine at full size on A4 paper (assuming you have a decent enough printer).

It's also slightly larger than HD, so will look fine on screen too.

If it's something that's ok to run for hours over night and you aren't too bothered with those hours, then of course you can go all out.

However, I would consider having a setup that also allows you to output exterior renders in under 5 minutes and interior renders in about 10 minutes.

My workstation has much worse specs and pulls this off, by starting off with the 'fast' physical render presets and just adjusting a few settings.

[Anonymous]

Thanks for your input, I understand it's a complex area but I also feel the ArchiCAD out of memory error is a bit of a false flag... The images will be used for an A0 composition, so not full A0 size but certainly bigger than A4, hence my desire to have at least 4K resolution images. I'll keep exploring the numerous options in photorender settings but given we're mostly happy with the renders ArchiCAD produces, the bugginess/non-linearity I guess is just something I'll have to live with or work around.

[Anonymous]

Erwin wrote:
by starting off with the 'fast' physical render presets and just adjusting a few settings.

Out of interest, why do you go with a physical preset? If I understood correctly it tried to replicate an image from a real camera, with options for aperture/shutter speed/DoF etc - I've usually found this slower than the non-physical option.

[Erwin Edel]

Kieran wrote:

Erwin wrote:
by starting off with the 'fast' physical render presets and just adjusting a few settings.

Out of interest, why do you go with a physical preset? If I understood correctly it tried to replicate an image from a real camera, with options for aperture/shutter speed/DoF etc - I've usually found this slower than the non-physical option.

Yes, physical renderer yields better results and some of the settings are like a camera, so if you know your photography, it's easy to set up.

The preset scenes for 'medium' and 'final' will take very long to render.

Are you using the grass effect, by the way? A large surface trying to create grass (or other displacements) will potentially make the render fail.

https://archicad-talk.graphisoft.com/viewtopic.php?f=3&t=61848&p=284456#p284456 here is a quick run down of exterior render settings I use.

If you are doing interior rendering, let me know, and I'll try to write up how I've gotten those down to max. 10 minutes.

[Anonymous]

The setting I use for interior renderings that are quick and give a good result are attached to this previous post:

https://archicad-talk.graphisoft.com/viewtopic.php?t=65964

Regards
Scott

[Anonymous]

Thanks everyone. The render in question was a funky one with the camera positioned in line with a window, half inside, half outside, I don't think there was grass involved but there were a few point lights dotted around....
Anyway, I've got some good ideas for next time!