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polyvalent painted drops: how to render?


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Alrighty then; I have a scenic drop to light, quite traditionally executed, to my general delight. Got all wound up in the idea of previz-ing a few ideas in Renderworks (def not Vision) for the client. The few times I have executed this idea in the past, the drops have been either simpler in execution or I knew less then or both.

This time the drop has the following attributes:

  • opacity
  • varied translucency
  • specular highlights (glitter paint)

My solve so far has been:

  1. image prop for the overall drop, with translucency determined by luminosity in PS
  2. translucent cyc behind that

this covers all but the specular bit. Help?

 

The attached image shows a close-up of the paint sample.

The drop overall is a sub tropical cityscape.

 

[The side-by-side is just because I got suddenly interested in who's interpretation compared to IRL worked best.

The Canon (2012) for color accuracy's sake kicked the iPhone 11/Halide Raw's ass all over the kitchen floor to my eye, as it was shot in daylight and directly compacted to the paint sample. Punchy as the iPhone/Halide version is, it's much livelier (& plain wrong) than the reality.]

Model this in VWX.png

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Specularity implies a direct reflection from the light source back to the camera (eye) where you are seeing the source itself. So the first thing that needs to happen is you need something to reflect, light sources in VW are infinitely small and will not cast a reflection.  Area lights do in other programs, I can't remember if they do in VW.  But you basically need something like an HDR background of what the lighting plot is, so that the reflective bits can pick them up at various angles.  Your spots of glitter paint are all reflective, but the actual surface is very bumpy and so therefore "glitters" as light comes from different angles to either be seen by your eye or not.  This effect is much more apparent when your camera/eye moves, picking up different specular highlights due to the changing angle of reflection.  

 

Maybe this part is a 100& reflective surface with an alpha channel applied to create the pattern?  Seems like a lot of work to me.  I would maybe just make the surface a breakup of all of the lighting tones you are using, in the glow channel.  After all, if the effect is specular, which is going to be the brightest thing in your picture anyway, why waste all that computation time with a light emitter to catch the reflections etc..  If I was only doing one shot, say the wide shot of the drop, I'd see if I could make a mask that you could use in PS to touch up the render.

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On 7/25/2021 at 12:14 PM, grant_PD said:

Specularity implies a direct reflection from the light source back to the camera (eye) where you are seeing the source itself. So the first thing that needs to happen is you need something to reflect, light sources in VW are infinitely small and will not cast a reflection.  Area lights do in other programs, I can't remember if they do in VW.  But you basically need something like an HDR background of what the lighting plot is, so that the reflective bits can pick them up at various angles.  Your spots of glitter paint are all reflective, but the actual surface is very bumpy and so therefore "glitters" as light comes from different angles to either be seen by your eye or not.  This effect is much more apparent when your camera/eye moves, picking up different specular highlights due to the changing angle of reflection.  

 

Maybe this part is a 100& reflective surface with an alpha channel applied to create the pattern?  Seems like a lot of work to me.  I would maybe just make the surface a breakup of all of the lighting tones you are using, in the glow channel.  After all, if the effect is specular, which is going to be the brightest thing in your picture anyway, why waste all that computation time with a light emitter to catch the reflections etc..  If I was only doing one shot, say the wide shot of the drop, I'd see if I could make a mask that you could use in PS to touch up the render.

@grant_PDthanks man, the glow channel alpha mask idea sounds like just the ticket.

Shots: Usually it's three/four shots from various audience positions, but basically all wide, so this solution seems appropriate to all.

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On 7/27/2021 at 3:53 PM, grant_PD said:

Also wanted to point out that you should probably render these at a pretty high resolution to get the ability to refine down to the small dots you are trying to show.

@grant_PD yup, agreed, tho I sneak up on that often through a couple scratch lo dpi viewports till I'm happier enough to go up-dpi.

I do wish I'd get with the program and learn to utilize cloud render efficiently.

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