Limiting a Fog's Height on the Y axis?

[Lee Groves]

Hi.
I am using the fog feature found under the Volumetrics tab \ Volume Integrator and would like to limit the height of the Fog from the ground.

I often see fog or a ground mist that covers the ground but is only about a couple of feet in height.
(Some times the fog or mist does not reach\touch the ground and starts above it!)

Is there a way of limiting the fog on the Y axis? - I was thinking a weight map but cannot see a way of applying it only to the Y axis.

I have also submitted a feature request for this.

Thanks.
LG

[JohnMarchant]

Wouldnt groundfog be more what you need. I think its legacy though if you are using 2018 / 2019

[Lee Groves]

Yes - Sorry forgot to mention I am using 2019.03
I have also tried applying a Gradient to the Y axis only using nodes - But it does not seem to work.
LG

[JohnMarchant]

I would say that for what you need which is the ground warming up in the morning creating this fog, groundfog is your option. Alas these are legacy which you cant mix with the new volumetric system.There is a YT on the groundfog, thing is now the old volumetrics is legacy and it you want to do it in 2019 it will involve nodes no doubt. Have you thought about using a VDB.

https://www.youtube.com/watch?v=IoS3m3YWChM

[Lee Groves]

John.
Thanks I will look at using VDB instead.
I wanted to see if it was possible using the current fog fx feature.
I would have thought that by applying a Gradient on the Y axis to the VolumeIntegrator's "Scattering weight" node input it would achieve the same effect.
LG

[JohnMarchant]

Im sure there is a way, how controllable it is is another matter. Vol lights in the old LW were for me far easier to set up than now. Trying to create a jet engine exhaust was easy before with a spot or two and nulls controlling the length, now you have to do it through nodes and whilst it is good its a lot harder and longer to set up IMHO. Do you have Ocatne, there maybe a better way through octane. Also look at a volumetric light on the ground pointing up, this might be another approach. VDB's are good but can be a bit of a hit rendering wise.

You might need to look into Houdini Apprentice or Blender to get the VDB type you want.

[prometheus]

Wouldnt groundfog be more what you need. I think its legacy though if you are using 2018 / 2019

No don´t use that, old stuff..and too darn slow.
Skip old voluemtric lights, it´s not easier than the new volumetric item.
Skip new Global volumetrics.
Skip VDB ..no need to unless you have made it specificly in another 3D software.

Use standard volumetric item in cube mode, you can stretch it as you like in height, width, depth..and also move it further or closer to any item inluding the camera...I have used it a couple of times and you can
control it so it works like haze, get distant orange brownish scattering at horizon etc.
You do need to set very low values for density and scattering though.

[Lee Groves]

Promethus.
Thanks.
For me VDB is waaaay to complex to learn for such a simple task\effect.
Your suggestion looks a lot easier and more friendly!

LG

[prometheus]

Promethus.
Thanks.
For me VDB is waaaay to complex to learn for such a simple task\effect.
Your suggestion looks a lot easier and more friendly!

LG

VDB isn´t really that complex to learn in order to use it when necessary, but it is really unnecessary to use in this case, this is just fog..without any clouds or any real texturing in them.

We have a thread going on about lower ground fog clouds, as well as VDB, which could do with some cloud texturing..two ways you can do is either paint a map where ground fog clouds is supposed to have its distribution, and then load that in
the volumetric opacity channels or texture channels..can´t describe it fully her now, that is none VDB

The other method would be to use Houdini and paint in fog where needed, add cloud noise and cloud lighting and save out to VDB, that is a bit more complex..but not really that hard, once someone shows the guidelines.

VDB tools in Lightwave would be to create a mesh, turn it in to a volume with the VDB mesh to volume node, then add velocity advection to generate a noise, that is very slow to simulate and hard to get feedback on in a fast way, ergo I find it faster and easier to overview in Houdini which doesn´t require a simulation of the noise, Houdinis cloud noise works on static volumes, even if they are converted from a mesh.
Once the vdb fog cloud in Houdini is made, you enter the nodes and check the last node (often the cloud light) hit tab/volume/convert vdb and use that..it will place a convert node after the cloud light, lastly you click on that and save, you do not even have to check any save format, just name it vdb as extension.
Then you can load that in to lightwave with a VDB set null.



https://forums.newtek.com/showthread...2-Clouds/page2

[BeeVee]

The effect of a ground fog can be realistically created using the volumetrics included in LightWave since 2018. I will be creating a tutorial for the docs although there is already a scene, created by Shaun Lee Bishop, in the content that shows the effect. Here is a little preview anim that shows a light, (too-) rapidly moving ground fog preview.

https://www.dropbox.com/s/h0fbwasi82...dfog2.mp4?dl=0 (because the file upload on this forum doesn't want to work for me)

B

[prometheus]

The effect of a ground fog can be realistically created using the volumetrics included in LightWave since 2018. I will be creating a tutorial for the docs although there is already a scene, created by Shaun Lee Bishop, in the content that shows the effect. Here is a little preview anim that shows a light, (too-) rapidly moving ground fog preview.

https://www.dropbox.com/s/h0fbwasi82...dfog2.mp4?dl=0 (because the file upload on this forum doesn't want to work for me)

B

Hi BeeVEe..
Where´s that scene content?

[Ma3rk]

Don't think it's on his YouTube channel but if you have or plan to get RH's LSR series, he's a really nice primer working with the new volumetric: 43_Fog.mov. Pretty sure the basics have been covered here, but looks to be pretty easy & straight forward to work with. I'm prepping scene nicely suited for it now so hope to test things by tonight.

[BeeVee]

The tutorial is not ready, but when it is, there'll be content to go with it.

B

[jwiede]

How does LW2019 handle cases where you might want, say, both a ground fog volumetric object, and clouds, in the same scene? Has anything changed w.r.t. the ability to control the scattering/volumetric-rendering settings on a volumetric object-by-object basis, either fully independently, ideally, or even just some easily-managed override mechanism?

For the record, these are the kinds of scenarios where nodes currently detract from ease-of-use, rather than enhance it, because the node flows to "select and bank-switch" are complex and generally involve a bunch of similar, onerous parallel setups. If LW is going to continue seriously pushing users towards nodes for these kinds of operations, then the devs really ought to at least provide either pre-made nodal compounds or native equivalents to ease construction these kinds of "by-n switch-multiple-attributes-based-on-selector" node flows.

If LW's market share is to ever grow again, the LW team must focus more effort towards providing of "canned nodal assemblies" for many common use scenarios, as well as provide utility nodes like canned "n-way switchers" etc. It's kind of sad that other packages whose nodal systems are much more recent additions (already) include substantially broader/deeper collections of pre-made examples, convenience assemblies, and utility nodes in-box compared to Lightwave.

Acquiring them doesn't have to cost much, have contests where good entrants become OOB content and newsletter/website publicity, or contract with LW content providers to produce assemblies (or even utility compounds) for similar coverage. Customers keep suggesting these kinds of ideas because they've worked really, really well for other packages, and would for LW as well.

[prometheus]

How does LW2019 handle cases where you might want, say, both a ground fog volumetric object, and clouds, in the same scene? Has anything changed w.r.t. the ability to control the scattering/volumetric-rendering settings on a volumetric object-by-object basis, either fully independently, ideally, or even just some easily-managed override mechanism?

For the record, these are the kinds of scenarios where nodes currently detract from ease-of-use, rather than enhance it, because the node flows to "select and bank-switch" are complex and generally involve a bunch of similar, onerous parallel setups. If LW is going to continue seriously pushing users towards nodes for these kinds of operations, then the devs really ought to at least provide either pre-made nodal compounds or native equivalents to ease construction these kinds of "by-n switch-multiple-attributes-based-on-selector" node flows.

If LW's market share is to ever grow again, the LW team must focus more effort towards providing of "canned nodal assemblies" for many common use scenarios, as well as provide utility nodes like canned "n-way switchers" etc. It's kind of sad that other packages whose nodal systems are much more recent additions (already) include substantially broader/deeper collections of pre-made examples, convenience assemblies, and utility nodes in-box compared to Lightwave.

Acquiring them doesn't have to cost much, have contests where good entrants become OOB content and newsletter/website publicity, or contract with LW content providers to produce assemblies (or even utility compounds) for similar coverage. Customers keep suggesting these kinds of ideas because they've worked really, really well for other packages, and would for LW as well.

You didn´t upgrade to 2019 did you? otherwise you can still test with the discovery version of Lightwave.

As we both mentioned about overlapping of volumetrics in the new 2018-2019 Lightwave version, it is no longer freezing as it sort of did with old hypervoxels when using several hv null items.
So you can simply use another volumetric item as I also mentioned I would do instead of messing with nodes and math with the global scattering system, Had they implemented a framework around the nodes with sliders for fog height, depth, density and anisotrophy/assymetry and scattering amount in one panel dedicated for the sky...that would be the way to go, Vue does this best in terms of UI, and after that we have Terragen.

But for a case like this, I prefer to use single volumetric item, and you can change values as you want independetly from other volumetric cloud items, so you can get away with a Higher step size (lower quality) for fog only.

The volumetric item has absorbtion options, which the global volumetric system doesn´t have, it only has scattering weight, no density control an no absorbtion control..which feels like it´s not really optimized to work as
a ground fog implemented volumetric technique at all, but maybe I am wrong?

in the image samples, I raised scattering scale, and raised Absorbtion scale for the fog item, in this case on the fog item, I have set the color to blue, thus when raising Absorbtion scale, it will absorb more of the blue color and become more orange red, just as in the real world with how blue light can´t travel through a denser atmospher or fog..and thus become red at horizon, but it´s a hack and not a true match of a volumetric physical spectral atmosphere..we still await for the Lw team to implement that aren´t we