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View Full Version : Alternatives to GI? / shorter render times / alternate lighting strategies?



jeric_synergy
03-18-2016, 12:27 AM
I'm dabbling in 360 renders, and foolishly tried to use GI because of the interesting soft/bounce lighting it enables.

OTOH, at the render size suggested by Google (3840x2160) the render times are brutal.

I have little patience for tweaking GI settings, so looking for a guidance to an alternative lighting approach in contrast to GI. AND, this is just for research/fun, so spending money on render services is out of the question.

Thanks.

Ztreem
03-18-2016, 04:03 AM
what is brutal render times for you? and what kind of render time is acceptable? What kind of scene do you have? Any images of the scene and render settings? You have to have in mind that when doing 4K renders the rendertimes will be least 4 times longer than Full HD.

Danner
03-18-2016, 04:06 AM
One alternative (with a learning curve, and pitfalls) would be to bake the GI to a texture and apply it to your geometry.

prometheus
03-18-2016, 04:22 AM
Various ambient occlusion ways, either by shaders or globally.
Dp dome light or native dome light, but not sure if they in fact will be faster since you will still need a lot of samples to get rid of noise.

Danner
03-18-2016, 04:23 AM
Did some math Just to compare resolutions.
DV (NTSC)_____720x480____= 345,600
720p_________1080x720____= 921,600
1080p________2080x1080__= 1,382,400
4k___________3840x2160__= 8,294,400

That means a 4k render takes 24 times longer than a DV render.

jeric_synergy
03-18-2016, 11:32 AM
One alternative (with a learning curve, and pitfalls) would be to bake the GI to a texture and apply it to your geometry.
Ooooo, that's clever!!!... on 2nd thought, I'm relying a lot on shadows and moving light sources for the feel, so, that probably is a non-starter. :cry:

Certain elements might benefit from that approach though, so maybe I can mix it up. I guess the trade-off for faster render time is a whole lot more setup time.

raw-m
03-18-2016, 12:48 PM
Using the RAW buffer and luma matte it to a shadow/shading buffer is a total cheat but can be useful.

jeric_synergy
03-18-2016, 02:09 PM
Using the RAW buffer and luma matte it to a shadow/shading buffer is a total cheat but can be useful.
Bear with me: Is this similar to texture mapping the illumination? At some point, the GI has to be calculated, esp. with moving light sources, no?

(tnx for everybody's help!)

spherical
03-19-2016, 12:44 AM
The Dome Lights, especially DPont's as it has its own sampling setting so that the global light samples can remain low, would work well. For interiors, as I detect that this is where your animation is centered, you would experiment with careful placement of Spherical lights and/or DP Flood to illuminate areas with soft shadows. DP Flood has: individual samples, diameter, cone angle, edge falloff and other unique stuff. With a little work, perhaps using object exclusion, you could replicate a GI look and have fast renders that are stable. Just takes a different approach and some eyeball grease.

JonW
03-19-2016, 06:45 AM
For photo montages I alway render A3 300dpi files, about 5000 x 3500 roughly, & am happy with an overnight render.

jeric_synergy
03-19-2016, 09:24 AM
For photo montages I alway render A3 300dpi files, about 5000 x 3500 roughly, & am happy with an overnight render.
This is for an animated 360 video, ~4kX2k, and the frames are running about 8min/fr. 900 frames. ~5 days of render.

I guess I could resurrect this old system here and maybe knock a day off with a teeny render farm. But some more up front work as advised above is probably smarter (plus, I don't want to have to live w/2 systems running constantly).

Thanks all!

raw-m
03-19-2016, 10:32 AM
Bear with me: Is this similar to texture mapping the illumination? At some point, the GI has to be calculated, esp. with moving light sources, no?

(tnx for everybody's help!)

Nothing special, just a couple of buffers out of LW and comped in AE, for example. Sometimes helps for adding bit of colour to the shadows. Doesn't always work!

jeric_synergy
03-19-2016, 06:09 PM
The Dome Lights, especially DPont's as it has its own sampling setting so that the global light samples can remain low, would work well. For interiors, as I detect that this is where your animation is centered, you would experiment with careful placement of Spherical lights and/or DP Flood to illuminate areas with soft shadows. DP Flood has: individual samples, diameter, cone angle, edge falloff and other unique stuff. With a little work, perhaps using object exclusion, you could replicate a GI look and have fast renders that are stable. Just takes a different approach and some eyeball grease.
Tnx for the suggestions: the main reason I went w/GI is because there are glowing elements in the Scene: a couple of lit domes, red eyes in a buncha statues, and an entirely glowing "dna molecule".

spherical
03-19-2016, 07:49 PM
The DNA molecule may be more difficult, but I bet it would work just fine using the technique that follows:

When I do light fixtures, to choose a pertinent example, I place a small Sphere Light that emulates the bulb in the center of the globe, name it something relevant and choose its properties. It illuminates the globe itself. Next, I place a large Sphere Light at the same location and size it to just over the diameter of the globe, name it Ambient_[whatever_the_bulb_name_is]. Then have it exclude the globe in its objects panel, color the light to emulate the globe, choose falloff type and adjust brightness and distance to taste. Fast, soft, gorgeous, independently adjustable. It is what is employed here:

132985 132984

You could do the same for the DNA strand by either a cylinder light made from an object, as seen in the Galaxy Table, or simply a stacked string of Sphere Lights that are roughly the diameter of the helix. Don't need to have each little node luminous just to give off a glow upon adjacent objects.

OFF
03-19-2016, 07:56 PM
~5 days of render
Not bad! It's time to start! ;D

jeric_synergy
03-19-2016, 08:15 PM
OK, finally home and I can post a representative frame here:
132986
So, the "DNA light" is directly behind the camera, so in this UberCam 360 shot you see it split in two at the edges of the pic. The whole thing is GI, as stated, but a lot of the lum. polys don't contribute THAT much I guess: for instance the DNA, the two floor domes, the eyes, and the red polys at the ends of the window tunnels are >100% luminescent (sometimes WAY more). Most of the remaining lights are LW Spots.

Since the "window tunnel" lights (glowing polys) don't even reach the end of the tunnels, that should be easy to replace with, probably, dome lights with Falloff.

Really, this shouldn't be that big of deal, I guess: fakery should be rather easy, and result in far faster renders, I hope.

The DNA light is probably the biggest challenge, but perhaps a light projection off a cylinder light would result in much the same look.

59 hours remaining on this render: I'm loathe to interrupt it. Frustrating thing about 360 renders is the camera is just SITTING THERE, since the viewer will eventually "become" the camera.

Ztreem
03-19-2016, 08:36 PM
This is for an animated 360 video, ~4kX2k, and the frames are running about 8min/fr. 900 frames. ~5 days of render.

I guess I could resurrect this old system here and maybe knock a day off with a teeny render farm. But some more up front work as advised above is probably smarter (plus, I don't want to have to live w/2 systems running constantly).

Thanks all!

A 4k render with GI in 8 min? I would say, that is a really good render time...
If its only some glowing things you want the GI for? You can fake it as Spherical also mentioned with some point/spherical lights placed at strategic places.