IR map modes

[Devin Johnston]

Hey everyone, I did a quick scan of the topics and didn't see this so if anyone has already posted this I'm sorry. I just upgraded to the final version of 1.5 and some things have changed, I looked on the Vray site but didn't see anything about the new modes under IR-maps (Animation (prepass) & Animation (rendering). On all of my previous animations to calculate the IR-map I've been using the Multiframe Incremental mode rendering out every 10 or 15 frame. With these new features it appears like you can use them to do both the prepass and the animation but I don't know what the pros and cons are or really what they do at all. One other thing, I've read that now you can use a render farm to calculate the IR-map, how do you do this?

[Devin Johnston]

No one knows what these modes do?

[Devin Johnston]

Let me say I'm very surprised that no one has responded to this and I've gotten no help on the Vray forum either. The only explanation I can think of is that people just don't know what these settings do or how they work. It makes me wonder why Vray 1.5 is released with no help documents, shouldn’t that be the first thing they do?

[Sawyer]

Devin - I saw these new modes at SIGGRAPH. I have not installed 1.5 so I can't help with details but what I saw was that the new animation feature blends irr maps from a series of frames. You set the interpolation for a number of frames that will bracket the current frame ie: a number of 2 creates a blend of 5 irr maps - the active frame + 2 in front and 2 behind the current frame. So you can have animated objects with smooth GI.

 

I am not sure if that helps.

[Devin Johnston]

Not really but thanks for trying anyway, I just need to know what I do after the prepass has rendered out every nth frame, and I have all these IR maps saved.

[salvador]

Hello Devin; I checked the changelog and yes theses modes are mentioned along with a blend control parameter between frames, but it doesn't explain much about it. I'm not relly helping you but I'll keep looking.

[Devin Johnston]

Thanks salvador I appreciate it.

[Devin Johnston]

Ok I think I've figured out how it's supposed to work.

 

1. Set all you’re setting to their final production levels

2. Select animation (prepass)

3. Specify a location to save the IR map

4. Render the IR prepass using either network rendering or your workstation

5. Once the IR prepass is rendered switch mode to animation (rendering)

6. Send to render farm

[manta]

Let us know if it works, haven't had a chance to test it yet...I'm surprized this hasn't got much attention, since it was a very big issue not being able to have moving objects in animations...I wonder if its just not that much faster than brute force...

[Devin Johnston]

Well it definitely works but you have to do prepass on every frame you can't use nth frames like you do with multiframe incremental, but it does allow you to render out moving objects.

[manta]

So how much time do you think it saves as opposed to brute force ?

[Devin Johnston]

I don't know it's pretty slow since you have to calculate each frame, I had at least 20 or 30 machines working on the prepass and that took several house with render times somewhere in the 4 to 10 minuite range. The final animation is still rendering with average render times around 1 hour per frame.

[landrvr1]

Wow, reading through this thread I just can't see what the advantage of this new method would be over brute force. Anybody?

[Christopher Nichols]

Sorry... I missed this thread... in now... there is a huge advantage of this over brute force especially for heavy GI stuff like interiors.

 

Here is how it works:

 

Set your GI settings to something pretty good (like medium or high). Then do a prepass. This saves a GI file for every frame. This can be done on the farm which is also a huge advantage. Also, the IR map is like 60% faster in the new 1.5

 

Next do the animation mode and load the GI sequence in.

 

The setting you need to work with the is interpolate frames number. This blends the IR data on proceeding and following frames. For example, if you have it set to 3 frames, then it loads the 3 frames before and after and blends the data. This smooths out the IR data and produces something with a pretty much flicker free result.

 

When using this method, I find that brute force for secondary is generally best since that is stored in the IR.

 

Using brute force for both can be brutal for heavy GI scenes.

[colorID]

hi Christopher Nichols

 

i dont really get what you mean?

 

can u please explain it more, do we have to render each frame for the moving object? or shall we render every Nth frame? would it work?

 

i ve tried it and no goos results.

 

thanks in advance

[landrvr1]

I've done numerous tests with the new prepass feature - playing with low to best IR settings, interpolation samples from 3 to 20 - but no joy. There's still a lot of flickering. In fact, just using IR and light cache - sent to a farm with no saved maps - produces much less flicker.

 

I'm curious to see if anyone else has done tests, and has gotten the prepass feature to work. High settings, with a sample number of 3, will produce IR map files of 20MB or more, FYI.

[johnvid]

So in laymans terms, this new IR map mode sounds to me like an Animated IR Map (or is it sequential still frames referenced to the current frame/camera), instead of a still IR Map. So perhaps the best way to use it, and I am guessing here, its the way I think it should work.

 

Render a couple of IR maps from different camera angles, to build up a nice big clean IR map for all the static geometry.

 

Then have some kind of channel ID for the animated parts, so that an animated IR map could be generated for the moving objects.

 

Mix the two together with the sphere fade thing(but not a sphere, an ID channel), Like the walking man example in the sponza atrium but with an ID for the overlayed parts.

 

Is this possible, and if not why not?