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HDRI Caustics Glass Affect Shadow
show user profile  FX
I've been tweaking for a few hours now but hit on an issue I can't find a solution for.

In order to generate caustics the glass shader needs to have affect shadow turned off?, which results in my glass being too dark, especially where the base touches the ground and for me totally ruins the caustics effect.

How do I get around this ? It took me 5 mins to make the scene and I've been fucking around for 5 hours trying to get the caustics right

Is there any guide anywhere that covers this ?











read 211 times
3/12/2016 2:21:05 PM (last edit: 3/12/2016 2:21:05 PM)
show user profile  speed
HDRI is a light map, not a real light source. You'd need to add real light source (i.e. target light) in scene to get caustic effect.
read 209 times
3/12/2016 5:38:47 PM (last edit: 3/12/2016 5:38:47 PM)
show user profile  Nik Clark
That's not strictly true.

IBL is image-based lighting and uses HDR maps.




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read 208 times
3/12/2016 6:05:10 PM (last edit: 3/12/2016 6:05:10 PM)
show user profile  speed
Nik- I am not saying IBL won't work. To save hours of pain. I'd simply add "invisible" light source directly to object to get caustic as a trick.
read 208 times
3/12/2016 7:01:21 PM (last edit: 3/12/2016 7:01:21 PM)
show user profile  FX
Yeah I've seen al the tuts using separate light sources, but what Nik said, you really have to crank up the settings and render times / photon calc are excessive, but you can get caustics.

The reason I tried with HDRI is I wanted accurate caustics not fake ones.

read 208 times
3/12/2016 7:02:02 PM (last edit: 3/12/2016 7:04:16 PM)
show user profile  speed
... Alternatively, you could adjust HDRI exposure in photoshop.
read 208 times
3/12/2016 7:21:31 PM (last edit: 3/12/2016 7:21:31 PM)
show user profile  FX
Annoying, HDRI gives me a great indication of what accurate caustics would look like, but doesn't respond to any of the settings in the render rollout, or rather it does, but it's only seen in the GI pass, which explains the massive increase in render / photon calc times.




read 206 times
3/12/2016 8:36:01 PM (last edit: 3/12/2016 8:36:01 PM)
show user profile  FX
Nik your right ...IBL should work :


http://www.vray.com/vray_for_3ds_max/manual/vraylight_examples.shtml#Example_5:_IBL_(Image-Based_Lighting)



read 203 times
3/12/2016 10:57:55 PM (last edit: 3/12/2016 10:57:55 PM)
show user profile  Error404
HDRs (both spherical/dome light, and rectangle lights mapped with HDRs) can absolutely create caustics, it's been that way in V-Ray for a looong time now.

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read 202 times
3/13/2016 2:10:09 AM (last edit: 3/13/2016 2:10:09 AM)
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