BIMx Global Illumination slow rendering

[Anonymous]

Hi,

I'm trying to generate a complex model (110MB) with GI and it takes ages ( over 2H).
On my computer while rendering the CPU usage is ~7% (Ryzen 8-core cpu).
Is it normal that it runs only a small percent of the what it could ?

[Katalin Borszeki]

HI, BIMx timeout with GI on is 25mins ≈ 1%, so it its normal that it takes time before publishing. In some cases it crashes after it finished. The GI calculation happens mostly on the GPU so you should keep an eye out for that column in the Task Manager. Best,

[Anonymous]

philips wrote:
CPU usage is ~7% (Ryzen 8-core cpu).
Is it normal that it runs only a small percent of the what it could ?

BIMx is a very old application (over a decade old, dating back to AC9) and, as of AC22 (July 2018), GI processing engine still does not support multithreading. The entire GI calculation for your model will run on a single thread (instead of 16 threads your machine is capable of), subsequently making GI calculations very slow. Unless this aging application gets a serious facelift (multithreaded GI, texture baking, etc.), this is not going to change any time soon. This single thread GI issue is true for both platforms (Mac OS X and Windows). You might take a look at some other applications on the market. There are some very similar to BIMx (albeit, not free, as BIMx is), with lights, texture baking and multithreading.

[Anonymous]

Hi I'm having the same query, only it seems to me that a single core of the CPU does most of the work most of the time, rather than the GPU. I do hope this will be addressed in Archicad 23. We want BIMx GI rendering to utilise all cores.

[Erwin Edel]

As it is we only calculate GI for single residential home projects, anything 'large' like a 40 appartment building just crashes.

[Anonymous]

christopherwilliams wrote:
Hi I'm having the same query, only it seems to me that a single core of the CPU does most of the work most of the time, rather than the GPU. I do hope this will be addressed in Archicad 23. We want BIMx GI rendering to utilise all cores.

Hi! I suffer from the same issues with super slow GI-rendering, is there any plans on improving this?

[furtonb]

+1

The GI calculation happens mostly on the GPU so you should keep an eye out for that column in the Task Manager.

My GPU utilisation is around 60%, and one core of my CPU is 100%, the rest is idle.

CPU multi-threaded rendering would be awesome for large scenes.
Is there a wish for this?

[Roland Szabo]

Hi,

Thanks for the feedback.
Archicad's GI calculation can be quite slow indeed, it's an old technology. We are aware of this issue, and keep it in mind during developments.

Yes, there is a wish about this: https://archicad-talk.graphisoft.com/viewtopic.php?f=30&t=69813

Kind regards,
Roland

[furtonb]

Thank you, Roland!

I hope this will get some attention in the upcoming releases.