PDA

View Full Version : Glow without the Glow feature



jbrookes
09-04-2018, 01:31 AM
Anyone know of good ways to make neon without using the built-in glow feature, luminosity, or image maps?

Could be for LightWave 2015 or 2018.

Ztreem
09-04-2018, 02:47 AM
Must it be done in Lw? I would do it in post. Like the soft glow in fusion/resolve for example. For stills you could use some glow filter in photoshop.

Render your neon light tubes with high luminosity and add a glow filter in post.

jbrookes
09-04-2018, 06:40 AM
Yes, it would need to be done entirely in LightWave.

RPSchmidt
09-04-2018, 07:39 AM
Anyone know of good ways to make neon without using the built-in glow feature, luminosity, or image maps?

Could be for LightWave 2015 or 2018.

Perhaps turn a copy of your neon tube into a primitive light?

https://www.youtube.com/watch?v=XUMfdZF8mRg

peebeearr
09-04-2018, 08:33 PM
Anyone know of good ways to make neon without using the built-in glow feature, luminosity, or image maps?

Could be for LightWave 2015 or 2018.

Well, You've got 2 flavours:
- Physical based
- Optical based

Physical based
This is where you have a medium (dust, fog etc) to transport your light emitting from your light source. This is a 3d volumetric effect (and pretty cool if you ask me!) It adds a lot of atmosphere to a (gloomy) scene.
142728
To get this kind of effect you need LW2018. Just enable Volumetric Scattering in Render panel
https://docs.lightwave3d.com/display/LW2018/Render+Properties+-+Volumetrics

Optical bases
This effect is done after the image has been rendered. In real life this is due to lens conditions, rather than (physical) environmental conditions. (scratches on lens, gogged up lens etc).
142729
As this is a post process effect, you need to use an Image Filter like Bloom or Corona. This is available in both LW2015 and LW2018. Also you can't really control the glow on a per-light bases, just as it is in real life camera's. Where the glow will be applied is determined by intensity of a pixel, the glow amount is controlled in the parameters of the Image Filter.
https://docs.lightwave3d.com/display/LW2018/Processing

So you need to think about your environment and what is actual going on that creates the glow effect to get the right kind of glow.
Hope that helps.

09-05-2018, 12:08 PM
Using Volumetric scattering creates really nice atmospheres of dirt and dust floating about.

MonroePoteet
09-05-2018, 12:25 PM
Per RPSchmidt's suggestion, the LW2018 Primitive Light seems to work great. It does require Luminosity (in this case 200%) on the geometry on which the Primitive Light is based, and the Glow post-processor adds a bit IMO.

142733 Primitive Light, 1lux

142734 1lux, with Glow

142735 0.2lux

142736 0.2lux, with Glow

142737 Primitive Light setup

mTp

Ztreem
09-05-2018, 03:37 PM
Did a quick test in LW2015 as I don't have any newer version. Using just luminosity and GI. (VPR Screenshots)

142738

Ztreem
09-05-2018, 03:54 PM
Anyone know of good ways to make neon without using the built-in glow feature, luminosity, or image maps?

Could be for LightWave 2015 or 2018.

I just reread your post again. So you want to create a neon light without glow, luminosity or image maps? Why?

If you only want straight neon tubes you can use volume lights. Hypervoxels could also work but slow...

jbrookes
09-06-2018, 11:50 AM
Thanks for the suggestions everyone! I see some great solutions there.

I was so used to the old Luminosity that I didn't realize that GI allows luminosity to cast light onto objects. So that's certainly a possibility.

Since I'm looking for a physical solution (as opposed to post-processing, which I'm trying to avoid), so far it looks like Luminosity + GI in LW2015/2018 or Primitive lights in LW 2018 are the best options.

Ztreem, did you mean Volumetric lights? In this case, I'm making bent neon tubes so I guess that eliminates volumetric lights.

As for why not to use the built-in Glow feature, there are a few reasons:
- It's resolution-dependent and needs to be adjusted if the output resolution changes.
- An object in the distance and an object in the foreground will have dramatically different levels of glow since its range is set in pixels.
- It doesn't cast its glow onto surrounding objects.

DonJMyers
09-06-2018, 02:56 PM
There is a neon example in the sample content scenes for LW 2018 - primitive lights - looks photoreal.

jbrookes
09-08-2018, 04:43 AM
So then I discovered the Primitive_Lights-Neon_Sign scene in the LightWave2018_Content\Scenes\Primitive_Lights folder.

It's exactly the result I'm looking for.

However, I only understand part of what's happening with the surface node.

I don't suppose some kind person out there might be able to walk me through what this scene's "Light Source" node editor flow is doing could they?

MonroePoteet
09-08-2018, 10:22 AM
Well, in terms of node networks, this one is very simple. If you're going to move into LW2018, an understanding of node networks is essential including how to "dissect" an existing node network posted in the Content or online. Instead of just explaining what this one does, here's how I'd dissect it.

First, render at least one frame of the Scene to have a visual reference of what's happening. In this case, NeonZ Entertainment has rendered most (if not all!) of the LW2018 sample scenes (THANKS!) and posted them on YouTube:

https://www.youtube.com/watch?v=V88Zs1MpZs0

Second, for clarity rearrange the node network onto "flows", or the sequence of nodes which feed each output parameter. I regularly collapse the Input node unless some of the input parameters are used in the node network:

142779 Jumble in original Content scene

142780 Rearranged into "flows" for each output parameter

Third, step through each node of each "flow", and lookup in the documentation what each node you don't already understand does by typing its name into the Search box on the LW2018 documentation page and navigating the various documentation pages:

Press F1 to get to the LW2018 website
Type "Gradient" (or "Incidence") into the Search box
Select an item in the drop-down list, or perform the search and examine the results
Select the "Gradient" (or "Incidence") node link:

142781

Read through the article to understand setting up a Gradient and the "Driving the Gradient" section using an Incidence node or a scalar Vertex Map=>Weight Map node:

142782

I tend to start from each output parameter, and look backwards in the node network feeding that paremeter. In this case, the output parameters are fed by two Gradient nodes, whose inputs are fed by a Weight Map node and an Incidence node. Gradients are an incredibly powerful tool and understanding their application will be critical for LW2018 versatility.

Double-click on each node to get its Settings panel, for example the Color and Luminous Color input Gradient and the Weight Map node:

142783 Color and Lumious Color Gradient, Weight Map node

142784 In Modeler, select points and view Weight Map value(s) with Information panel ("i")

Try to describe in words what each "flow" does. For example:

"The Color and Luminosity Color outputs use a Gradient to range from white to light blue based upon a Weight Map called neon_color. The Lightwave logo portion of the mesh has a Weight Map value of 100% making it light blue, while the Lightwave word portion of the mesh has a Weight Map value of 0% making it white."

and

"The Luminosity output is driven by a Gradient's Alpha output, ranging from 0% to 200% (Key 2 Alpha Value input is a Scalar node with a value of 2.0, or 200%) based upon the Incidence angle of the geometry to the Camera, making the center of each tube bright (facing the Camera with an Incidence of 1) but the edges (facing tangentially to the Camera for an Incidence of 0) dim. The Gradient has a Hermite spline type curve, enhancing the center of the tubes for a nice neon effect."

Hope it helps!

mTp

jbrookes
09-08-2018, 05:50 PM
Thanks!

Okay, here's how I interpret it so far. Of course, in the process, it raised more questions:

Gradient 1 handles the blue neon for both color and luminosity color. However, it looks like the Color
input is optional for this scene because luminosity is pretty much totally obscuring the surface color channel.

Gradient 2 handles the alpha which is applied to Luminosity. So this appears to be supplying the glow effect.

And the weight map seems to be controlling where the color falls on the neon object with "Gradient (1)"
dictating the colors that are displayed in the render.
Points in the LightWave logo are at 100% and are showing up as blue. Points in the neon text are set to 0% and
are showing up as white. This suggests to me that 100% in the weight map correlates to 1 in the gradient.

The Incidence node seems to be there so that the area that the camera points directly at on the neon
object is 100% visible and becomes less visible the more off-angle from the camera the geometry becomes.

Incidence range is set to 90 degrees.

Q: What exactly is happening when you change from a Range of 90 degrees and 180 degrees? I only see a very subtle difference
in render output between the two available angles in this scene.

Q: In reference to "Incidence", the manual likes to use the phrase "current hit point". What does this refer to?


A Scalar node is plugged into the Alpha for Gradient 2.
Q: Is there another way to boost the effect other than adding a scalar to double the second alpha key?

The manual seems to be pretty sparse in its description of the Incidence node. A few diagrams in the documentation would clear things up pretty fast.

MonroePoteet
09-08-2018, 07:36 PM
Yes, in this case the Luminous Color overwhelms the Color of the surface itself. The Primitive Light is what produces the "glow" effect, not the geometry's luminosity. The "Sample Surface" button is enabled on the Primitive Light, so the surface's color (as specified by the Weight Map and Gradient 1) are propagated to the Light's color and thus the illumination of the wall behind the light.

142787

Yes, in general "100%" mean 1.0 in most cases.

The Incidence node controls the Luminosity, not the visibility (i.e. transparency). So, the center of the tubes (whose polygon normals are facing the camera) are very bright, while the sides of tube (facing to the side) are dimmer.

I would expect changing the range on the Incidence node to 180 to just make the very edges of the tubes slightly brighter and the highlighted center of the tubes slightly narrower. The polygons facing away from the camera (i.e. on the back side of the tubes) which have incidence angles between 90 and 180 degrees are not visible due to the tube itself. The Hermite spline on the Incidence driven Gradient's Alpha has a "knee" close to the top of the range and close to the bottom of the range, so it doesn't drop off to zero (i.e. not luminous at all) until very close to the edge of the tubes, so changing it to 180 just brightens the very edges of the tube slightly.

"Current Hit Point" means the point on some visible geometry (or in a volumetric) whose visibility, luminosity, color, specularity, etc. are being calculated by the ray-tracing render engine.

Incidence just means the angle between a "hit point's normal" (i.e. the direction it's pointing) and the ray from the camera (or Light in the case of Light incidence). On a single, flat polygon which has one normal (i.e. only points in one direction), you change the Angle of Incidence by rotating the polygon in Heading or Pitch relative to the Camera, or moving the Camera around the polygon.

You can see the results of Incidence easily by making a Gradient with bright red at 0.0 and bright blue at 1.0, feed Incidence into the Input, and apply that Color Gradient to any geometry. The closer a polygon is pointing directly at the camera, the more blue it will be, while the farther toward the side it points, the more red it will be, producing a full range of purples.

142788

142789 Incidence / Gradient Setup

To increase the neon effect other than Luminosity on the Surface, you could increase the Intensity of the Primitive Light, currently at about 25lux. The Scalar input (of 2.0) just makes it a little easier to open that node and type in the value than opening the Gradient, selecting Key 2, selecting the Value of the key and typing in the new value.

mTp

jbrookes
09-09-2018, 06:54 PM
Thanks again. I tried out some tests and I can see what you mean by the Scalar node being the easier way to boost the luminosity.

I was initially confused about the affect the Incidence node has, but after some tests on a simple 10-sided barrel object, I can see that (as you mentioned) the polygon that's 90 degrees to the camera (facing the camera) has the highest value and the value being output from the incidence node drops off as the polygons face progressively more and more away from the camera. And the 180 setting just doubles the range (which usually results in a less-dramatic affect).

For current hit point, in the case of camera incidence, I imagine the incidence angle of a current hit point for a polygon that is facing a camera (poly at 90 degrees to the camera) is zero degrees since the poly's normal and the vector of the camera are both exactly the same?

As an additional aside:
I couldn't find a good Incident Range explanation in the LightWave 2018 docs and the explanations in both the LightWave 9 Surfacing & Render manual and in the LightWave v9 Texturing book might potentially confuse people. The LightWave 9 Surfacing & Rendering manual suggests that a value of 1 is output from the Incidence Node for facing polygons "faces at zero degrees to the camera" [p. 262]. Whereas the LightWave v9 Texturing book states that, "The part of the surface that faces the camera directly is at 90 degrees" [p. 322]. So I think maybe the LightWave 9 docs meant to say 'faces at 90 degrees to the camera' or maybe 'normals at zero degrees to the camera'.

P.S. Is it just me or is there only one level of Undo for the Node Editor proper and no Undo levels for when you move a key in a node gradient?