Hi people
i noticed that krakatoa uses a huge amount of ram when i render with MBlur and save passes
if i use the iterative Full i have around 5gb of ram usage but when i go to render the sequence with some passes activated i can’t afford the render also with 50gb of ram
how to fix this?!?
thanks in advance
Can you share more info about the passes? Have you looked in the Memory Channels rollout what channels are listed there and how much memory a specific number of particles would require?
Some render elements might need a specific data channel to output information. For example, the Specific Light pass will allocate a channel called _Element_XX in memory where XX is the node handle of the object. If you have 10 lights and 10 render passes to output their illumination, you would be adding 60 bytes to each particle’s storage.
If you create a customData render element using Magma, any channels accessed by that Magma via InputChannel operators will have to be allocated in the memory cache at render time. The Memory Channels rollout should list these channels if that’s the case.
But when you render in Iterative mode, no Render Elements will be rendered, so your memory usage might be significantly lower than the actual full render.
Without knowing what memory channels you are requesting via the render elements, I cannot really tell you where the problem is.
Hi Bobo
it happens also with velocity pass only
the overall impression is that the kind of pass has no weight…as soon as i activate the passes it slows down terribly cause of the memory
it starts to do scratch drive memory and it goes from 10 minutes x frame to 4 hours…at 4k res
one more data, i’m doing 32 mblur passes at 180degrees
so memory fills up quickly
how to check how much memory the pass needs? is there a kind of probe tool for that?
Yes, partially. According to this, only 38 bytes will be used per particle, and 100 million particles should use only 3.5 GB RAM.
I wanted to know what passes you are rendering, too, but if this rollout does not show any extra channels, you are probably not doing anything fancy with Render Elements…
What build of Krakatoa (exact version number) is this?
Hi Bobo that’s a screen grab of what i’m rendering
and this is the release installed on my machine…if you need to know more just ask 
Thanks, I was able to reproduce the issue and have passed it on to the Krakatoa developers to look into and provide a fix.
The number of particles plays no role at all.
The number of render threads does not change the outcome (tried single-threaded rendering, same result).
The output resolution DOES play a significant role.
In short, when motion blur is on and at least one render element is enabled, the image buffer of the render element is kept in memory for every pass, and at the end of the motion blur passes all image buffers are merged together.
In contrast, the RGBA beauty pass of the renderer does the blending of the image buffers after each motion blur pass, so it does not use up all the memory with image buffers.
We are looking into why we had to do that. The two outputs work very differently, as Render Elements from Krakatoa only represent the closest particles to the camera, overwriting anything behind them. In fact, Render Elements barely make any sense in Krakatoa, as they don’t represent the volumetric data in each pixel, only the closest particles to the camera. We added Render Elements because people asked for them, not because they are any good 
And Motion Blur plus Render Elements make even less sense in practice - if you will be rendering a Velocity Pass, it is probably meant to be used for motion blur in post…
However, since the combination of Motion Blur, Render Elements and high-res output are a valid setup, we consider this a bug and will be looking into fixing it (or disallowing that setup).
Thanks for the feedback!
wow we discovered a new bug 
BTW i’m closing the project setting the mblur passes just at 4 or 8 and reducing a lot the degrees then use the velocity channel in comp
compers ever ask a lot of passes because they are used to have them from other departments
in this case they are saving the day with the velocity pass so you did well to implement them
it’s a pleasure to help good tools like krakatoa to growUP
and thanks for all your support!!!
Thank you once again for the bug report, we got it fixed!
However, it is currently planned to be part of a 2.5.x point update together with some more fixes from the last week.
Does your company have any plans to update to 2.5?
Also, what version of 3ds Max are you running?
Hi Bobo sorry for the huge delay!
i was a freelancer in that company at that moment, now i’m another part of the planet but i can answer to one question you made
they were using max2016 with a set of custom tools for tasks management
if you need to know more feel free to contact me in P.M.
thanks again!!
