Questions on Vray fly through animation tutorial

[timmatron]

Great tutorial, but leaves me with a few questions.

1) Why a fish eye camera for the light cache calc. phase?

2) Do you switch to standard camera when you calc. the irradience map?

3) Why do you need to use the light cache for first and second bounce?

4) Why exactly do you have to calculate the light cache in one pass and then do the irradience calc. in a seperate phase? Is it because you only need to do one frame for the light cache to get the full gi solution since it is set to fly-through?

5) Do you want to keep 'store direct light' off when doing the light cache? I noticed on the tutorial file it was turned on and I imagine this saves a lot of time.

6) In the last Q&A, it says "You can have the light cache saved with the irradiance map". I don't understand that part. Can somebody explain that? Is it faster to not have the 2nd bounce turned on, or is it faster to "use light cache for glossy rays"?

Well, I guess thats it. Thanks in advance.

[Giovanni]

Well, I have been reinterpreting that tutorial, and simplify it.

I gave up one of the light maps calculations.

What I found to work quite well is:

1. first pass: every 15 or 20 frames, Irrmap first, incremental multiframe, LC second, flythrou mode. Autosave irrmap to a specific file/location. Autosave LC map to a specific file/location AND AUTOSWITCH to it.

What happens is: v-ray calculates the LC, for the whole animation, then saves it and uses it for the IrrMap rendering, which follows, every 15 or 20 frames. The IRRMAP uses information from the LC pass, so the saved IRRMap is actually all you need in term of saved illumination.

2. Second pass: every frame, use saved irr map, turn off any secondary bounce. Unless you use the LC for glossy, then you may want to set second to LC, using the saved LC map...

This has worked pretty fast and well for me (no flickering, decent quality). Can any "veteran" confirm I am not loosing anything in the process?

Thanks,

regards

gio

[vlado]

Re: Questions on Vray fly through animation tutorial

1) Why a fish eye camera for the light cache calc. phase?

For no special reason; it could have been any camera type.

2) Do you switch to standard camera when you calc. the irradience map?

No, the same camera type should be used throughout the process.

3) Why do you need to use the light cache for first and second bounce?

In the first part, because it illustrates better some of the points in the tutorial.

4) Why exactly do you have to calculate the light cache in one pass and then do the irradience calc. in a seperate phase? Is it because you only need to do one frame for the light cache to get the full gi solution since it is set to fly-through?

You don't have to do them in separate passes, you can combine them in a single step, like Giovanni suggested. In the tutorial, they are separated because it is easier to explain and demontrate what is going on.

5) Do you want to keep 'store direct light' off when doing the light cache? I noticed on the tutorial file it was turned on and I imagine this saves a lot of time.

This is as you wish. Storing the direct light in the light cache speeds up the irradiance map phase quite a lot (but is a bit less precise).

6) In the last Q&A, it says "You can have the light cache saved with the irradiance map". I don't understand that part. Can somebody explain that? Is it faster to not have the 2nd bounce turned on, or is it faster to "use light cache for glossy rays"?

It was simply meant that the irradiance map stores the final GI solution, and you don't need the light cache anymore - it is used just as an aid for calculating the irradiance map, and so you can turn it off during the final rendering. However, if you want to use the "use light cache for glossy rays" option, you will need to keep the light cache for the final rendering.

Best regards,
Vlado

[timmatron]

Thanks for those answers both of you. When I read that tutorial I thought I had been doing a lot of things wrong this whole time, but now I realize I've only been doing a few things wrong.