question: rendering animated lightsources, how??

[Dirk71]

Hi,
i´m currently trying to render a camera-animation with an animated texture. the texture consists of a sequence of 100 single jpgs
in a VrayLightMtl, mapped onto an object in my scene. i want to achieve a look which is similar to a tv-monitor. because my
camera ist moving and the light is changing in the scene i used the animation-preset for the irradiance map. but what gi-engine
do i have to use for the secondary bounce? lightcache? brute force? and do i have to calculate the secondary bounce while i´m
rendering the irradiance-prepass or in a separate pass later, or before?

any tips would be very nice!

dirk

[Shimakaze]

I'm not sure about this, but since Light Cache is saved inside the Irradiance Map, and the animation mode saves a separate irradiance map for each frame, you should be able to do the GI calculation using Light cache as second bounce for the prepass and then using none for the second bounce when rendering.

I guess depending on what's on the TV you could render out just a few individual frames of GI and composite them in post...

[Dirk71]

Hi Shimakaze,
thanks a lot for your reply! When the "Light Cache is saved inside the Irradiance Map", do I
have to activate a special setting or is the lightcache saved by default in the irradiance map?

I tried this method:
I´ve rendered the irradiance maps for each frame by the animation preset with secondary
bounce = none using DR. Then I switched to the "rendering"-preset, setting the secondary bounce
to lightcache (1500 Samples) and rendered the final images via backburner.

and it seems to work fine so far! But in this "workflow" the
prefiltering of the lightcache needs ages to calculate. A quadcore needs 20 minutes to render
one frame of the animation. This is twice as long as if I would render just a single frame
without any animation preset schnickschnack. Is that the result of rendering the irradiance-
prepass without secondary bounce?

I think there should be some more tutorials, especially for the "new" presets on the vray-helpsite.


Best regards,

dirk

[Shimakaze]

Nonono you got it backwards
You need to set set the light cache as secondary bounce in the first pass. Then in the second pass the light cache has been saved inside the irradiance map (because both were calculated at the same time) so you should set secondary bounce to none.
In other words...
First pass:
Primary bounce - Irradiance map, Animation (prepass) mode
Secondary bounce - Light Cache
Second pass:
Primary bounce - Irradiance map, Animation (rendering) mode
Secondary bounce - None.

[Dirk71]

Ah, ok! I don´t know why I`ve chosen the complicated way -- although this seems to work too
Thanks a lot for your advice! I will try it next time.

Best regards,
Dirk

[Shimakaze]

Well you could just render out the whole thing with the default irradiance map mode and light cache in a single pass and it would work fine too. You would have to recalculate the GI if you wanted to re-render it though.