spline glow techniques
Posted: 09 May 2017 03:43 AM   [ Ignore ]  
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Joined  2015-11-30

Hello,

I’d like to make a visibly glowing spline render, with adjustable falloff and physical render compatibility. Actual light /illumination are not essential. Just the appearance of laser type glow. Ideally as efficient as possible for busy scenes.

Approaches:

- Hair material: this will render the spline and allow use of Physical render, but hair material does not have a luminance channel so it looks shaded. Also, I don’t think it has a “glow” type option, where opacity falls off along radius. You can turn up the colour brightness, or use an ambient light to simulate luminance.

- Cloned Volumetric lights: This seems like the best option, aesthetically, but its really slow to render if you want even just a few splines, I set the light just to Visible rather than volumetric, to disable volumetric shadows. But its still very slow, and you can’t set the cloner to render instances either.. and its not resolution independent (without some xpresso tweaking)

- sketch n toon: glow effect possible, but obviously no phys render compatibility (dof, moblur etc), slow to render, overlapping issues, fiddly to combine with lit elements.

- Sweep Nurbs / geometry: I will continue with this method if no better option is available. If I really want glow without using obj buffers in post then I can try the glow post fx option. The main downside to using sweep nurbs is that it can glitch out on sharp turns, it needs a lot of polys for complex shapes and depending on thickness, transparency can become an issue. But it still beats the previous options and is good for using instances.

I’ve been looking at this tools4D plugin, “White Lights” for a while now, but I’ve always ended up not buying it, because I haven’t needed it on a job yet. It looks like an ideal solution but after watching the video (https://vimeo.com/71983343) I noticed some possible issues with this, primarily that it seems like the colour control is globally set in the render settings. I guess this isn’t the appropriate place to discuss the issues though..

Well, I feel like I’ve explored all the options, but I should spend more time trying experimenting, I think the sweep/geometry approach with material glow feature might be a good way to go. But maybe there’s some tips and tricks I’ve missed..

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Posted: 09 May 2017 08:41 AM   [ Ignore ]   [ # 1 ]  
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Hi NNenov,

The shaded appearance comes from the Specular channel. Note that you can dial in values above 100% for the Color channel in the Hair material. If rendered out as 32bit/channel (Open EXR for example), this value will carry over and is easily separate-able in post. With its strong values any blur in float will deliver that energy.

The idea that I like to add to your list, would be based on the old way doing stuff, with “sprites” for example. Just tiny little polygons (Clones) “looking” always to the camera. Rendered as Instances, it shouldn’t really matter how many of them are in the scene, the target stuff can be cached if needed.

Similar to that could be a Spline Wrap set up.

Have a look:

Scene File
https://www.amazon.com/clouddrive/share/byO3YGyaGLV3NqmEtnaW72O8KETbWOSKBeReu85tEue?ref_=cd_ph_share_link_copy

I have switched two of the three Polygons off. The other two are more needed if there is any interest in some reflections. But then I would add a gradient to the sprites’ Alpha and have “glow” already done inside the scene.
I’m not clear if that is clean enough for you, it certainly has some downsides, perhaps even artifacts, so that is more an idea than a solution.

Scene file
https://www.amazon.com/clouddrive/share/JoSSB8zNeU0BIaA03WbEDrdZJcqCJSniS0yKLRQJKA5?ref_=cd_ph_share_link_copy

Perhaps the gradient idea works better with the Spline Warp set up, with a linear 2D-U Gradient.

I hope that helps or at least leads to some new ideas for your project

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
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Posted: 09 May 2017 08:56 AM   [ Ignore ]   [ # 2 ]  
Total Posts:  107
Joined  2015-11-30

Wow that is awesome! To use the rail as a child of the camera.. I never would have thought of that!
That works really well, in some situations you get the flipping but its definitely worth using in certain situations, the render time is by far the best with this option.
I disabled glow and changed it so it uses a gradient in the luminance channel, then set it to transpernt in additive mode.
Also thank you for the sprite suggestion, this is well worth trying
Thanks Dr.Sassi!

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Posted: 09 May 2017 09:07 AM   [ Ignore ]   [ # 3 ]  
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You’re welcome, NNenov!

Yes, as I wrote, some downsides. The flipping might be countered with two or three elements set to x, y and z each time.

My best wishes for your project.

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
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Posted: 09 May 2017 09:41 AM   [ Ignore ]   [ # 4 ]  
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P.S.:

There is as well the option to use the spline as guide in Hair, and have Hair generate the results in Flat, Triangle or something else.

Scene file:
https://www.amazon.com/clouddrive/share/qcaxB72KgYpjCuLRfYqvEnXEJ3mmBKFUO3S1aeXzNsM?ref_=cd_ph_share_link_copy

Please note that the Hair material is here in use only to define the size (thickness)

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
https://www.youtube.com/user/DrSassiLA/playlists

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Posted: 16 May 2017 02:26 PM   [ Ignore ]   [ # 5 ]  
Total Posts:  107
Joined  2015-11-30

Thanks Dr.Sassi, always appreciate your extra input!

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Posted: 16 May 2017 02:29 PM   [ Ignore ]   [ # 6 ]  
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You’re welcome, NNenov, thanks for the feedback.

Perhaps we need to make a suggestion to have the Hair-Render Tag allowing glow wink
I guess it would be an appreciated addition.
https://www.maxon.net/en-us/support/suggestions/

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
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