Lightcache - Use Camera Path and Flythrough mode

[tricky]

When performing an animation (camera movement only), we tick on flythrough mode for LC. Then there is the Use Camera Path option. Could you explain the difference? I would have thought Flythrough mode means that it is using the camera path anyway.

[super gnu]

I've often wondered this, and never found a proper explanation beyond thing like "use camera path is for short paths in a single space" which doesn't explain very much.

[tricky]

I'm starting to think VRay (and rendering in general) tech is leaving behind basic questions like this. A few years ago, we'd have had a quick reply to something as simple. 4+ days have passed on this one. I guess doing several searches of the forum, and lots of digging around could yield an answer... #FeelingOld #We ArentAllUsingVRayNEXT

[leehumphries]

Richard - found this post from 2017 from vlado dont know if it helps
05-06-2017, 05:04 PM
When you choose "Fly-through" mode and you render a sequence, the light cache will be computed just once for the first frame, and then for the rest of the frames in the same render, it will reuse the cache in memory. This means that the only thing that can be animated is the camera.

When you turn on the "Use camera path" option, the light cache will still be calculated for each frame, but it will be more consistent from frame to frame which would potentially reduce flickering. In this mode you can have moving camera or objects - it doesn't matter.

Since we added the "retrace" option in recent builds though, it makes less sense to use any of these options. Most of the time, you can just leave the defaults and only increase the light cache subdivs if needed. The speed-up you get from the adaptive lights is usually more than enough to compensate the recalculation of the light cache for each frame.

Best regards,
Vlado

[Morne]

What Lee quoted and what Vlado said.

Just use defaults and single frame mode, (hover over the LC values and you'll notice the tooltips which Lele put together, suggesting 3000 subs for animation and 8.0 for retrace) In my tests this works great for most archviz type of things.

Make sure you don't have overly bright white walls etc (NO walls with diffuse of 255,255,255). High "white" values grinds LC to a halt.

[tricky]

So what about if you use flythrough mode *and* use camera path? (I have only moving cameras)

EDIT: having flythrough mode AND use camera path enabled, saving the LC and then using that for a sequence of frames would work...or not??? (with just a moving camera)

[humfrez]

I am rendering an animation with only the camera moving, I am pre-rendering an Irradiance map at every 15th frame. Will this every 15th frame setting work correctly for the Lightcache too or does it need to be pre-rendered for every frame? Back when there was an option "flythrough" the whole camerea movement range got rendered in the beginning for the whole duration.

[^Lele^]

We keep saying this (try a forum search.), but it's clear it doesn't stick.

Do *not* use any precalculation, follow our guidelines for the best performance we can offer (from first render to last.) bar none.
This, as Morne mentioned, means that from default settings (our factory default. make sure there are no v-ray render presets, or maxstart.max files which override those.), one only needs to change LC subdivs and Retrace.
Then animate just the camera, or everything at once, it's going to be of no concern.

Rendertimes will suffer with precalculation as none of the adaptive rendering tech will be able to work (no adaptive dome, no adaptive lights.).
Further, any issue in a precalculated sequence (they normally end up appearing at sequence end, as it's the case for the type of tech) will force a single pc to recalculate it all, leaving the farm idle.

Those modes have disappeared from V-Ray 5.

The same goes for the IRMap: the sooner it's dropped from workflows, the better.
It won't work with a number of techs (present, and a few of the future ones), so any expectation of time saved will be sorely disappointed.

p.s.: I wrote the tooltips, true, but they have all been done under direct supervision from Vlado.

[jeremiah_jones]

Moving forward with new tools is great and all and appreciated but I'm facing a case of having to update an animation done with Vray Next that is no longer rendering as expected using Vray 5. I was using IR/LC solution with pre cacls and was happy with results and time it took to render. At this point I can't downgrade my software and farm. Going this new route of BF/LC seems to either introduce a ton of noise or extremely high render times. I'm at a bit of a loss as to what to do in order to get the animation to render and look as good as it did and render in the same amount of time. Any suggestions would be helpful.

[^Lele^]

Moving forward with new tools is great and all and appreciated but I'm facing a case of having to update an animation done with Vray Next that is no longer rendering as expected using Vray 5. I was using IR/LC solution with pre cacls and was happy with results and time it took to render. At this point I can't downgrade my software and farm. Going this new route of BF/LC seems to either introduce a ton of noise or extremely high render times. I'm at a bit of a loss as to what to do in order to get the animation to render and look as good as it did and render in the same amount of time. Any suggestions would be helpful.

Use V-Ray Next.
Besides what we changed for V5, it's generally an undisputedly good thing to use *precisely* the version of software (this includes Max, and all the ancillary plugins, like fPro and such.) used to deliver a given job, should an update/rerender happen.
No one can guarantee identical results from wildly varying software versions and combinations thereof, and no one does (nor ever has, to my memory. Progress would be impossible otherwise.).

All this said, if you load the scene with V5, all the settings will be kept as they were, including the precalculated stuff.
There will however have been some changes in the underlying tech since then, so the frames are unlikely to look 1:1 identical: your only real choice will be to return to that ecosystem.

[jeremiah_jones]

Use V-Ray Next.
Besides what we changed for V5, it's generally an undisputedly good thing to use *precisely* the version of software (this includes Max, and all the ancillary plugins, like fPro and such.) used to deliver a given job, should an update/rerender happen.
No one can guarantee identical results from wildly varying software versions and combinations thereof, and no one does (nor ever has, to my memory. Progress would be impossible otherwise.).

All this said, if you load the scene with V5, all the settings will be kept as they were, including the precalculated stuff.
There will however have been some changes in the underlying tech since then, so the frames are unlikely to look 1:1 identical: your only real choice will be to return to that ecosystem.

I understand but at the same time it seems unreasonable to have to maintain every possible older software that was used in the chance that something may come back. I would like to move forward with 5 if possible. I love the idea of not precalculating any GI. I guess I'm just having some trouble tracking down what is causing the noise in my scene for sure. It seems like most of the scene is rendering as expected but the glass seems to be noisy and is different frame to frame in the animation test I'm doing. I'm not sure if it is the glass material, the render settings, or the mesh lights behind the glass. I know it is hard to track down exactly without seeing the scene but would there be other things I should be looking at? I attached a couple shots with some settings. These are both before using Denoiser. I get that the image sampler settings are not default and are low but I'm fine with the way that Denoiser cleans it up. My main concern is how the noise looks from frame to frame as it really stands out in the glass on the building. I really appreciate your help and again would love to move forward with Vray 5 rather than go back since it would be a big pain.

[^Lele^]

Your image sampler is too low.
IRMap did away with most of the details, so your glasses look clean, but frosted.
Notice how BF is resolving the light shape behind glass properly (unlike the IRMap which splotched it.), but because the max AA is too low, it doesn't have enough samples to clean it.
There is no direct mapping of settings between v4 and v5, either, in terms of noise profile, as things had to change to resolve some issue.

The suggestion is always the same: reset to defaults, touch *nothing* but the LC presets, do a couple of tests at key points for noise profile (if too high, raise max AA, or LC subdivs, or LC retrace threshold. Do a forum search for more detailed explanations on the three.) and send to render.
The set up should take near zero time, time that can be spent by PCs rendering the sequence, which ought to be a lot cheaper than paying someone to fiddle for days to no end.

In animations, i'd also strongly suggest using the V-Ray denoiser, as you can get multi-frame denoising done (as an offline process with the provided exe file, or via Nuke with a free downloadable tool.), which will allow you to get away with extremely low settings, and high noise levels, without compromising image quality at all (in multi-frame mode it'll detect what is detail and what is noise nearly unerringly, and won't blur at all.).

[jeremiah_jones]

I guess for me I haven't been spending a ton of setup time since I was using similar settings/workflow for many years. I get what you are saying though and how that might help some users and companies who are spending lots of time messing with it but having something take 4 times longer a frame is a big concern of mine. Based on the posts I'm seeing in the forums I'm not the only one with such concerns.

[jeremiah_jones]

Also if it were marginally slower it wouldn't be as big of an issue but a frame that took 15 minutes on average now taking over an hour is a big difference. So it still forces me to go back and play with settings because that timeframe just is not acceptable.

[jeremiah_jones]

I can't seem to get the standalone denoiser to work. Is there documentation on what needs to be done in order for it to work. When I import my origRGB element and click denoise it just closes without seeming to do anything. Do I need to save other elements?