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RPSchmidt
02-19-2019, 06:56 AM
Hello fine folks!

I have an OpenVDB explosion that I created and it looks really good... I mean, to me, it looks great!

The one thing that is missing is light; I've got all the appearance of an explosion, but it isn't giving off any light at all.

Is there something I need to add to get my explosion to give off some light? A node, perhaps?

Right now, I just have the values set in the OpenVDB properties using an OpenVDB sequence I created in another program. This is on LW2018.

Tobian
02-19-2019, 07:04 AM
https://docs.lightwave3d.com/lw2019/reference/rendering/rendering-and-compositing/render-properties/render-properties-volumetrics you need the render properties 'indirect sampling' selected, so radiosity works with volumetric voxel objects (VDB's)

Oh and Radiosity of course needs to be on too...

RPSchmidt
02-19-2019, 07:17 AM
Thanks muchly for pointing me to that, Tobian. I was going to turn on indirect sampling, but something in my head said "You don't need that". I guess it was the part of my brain that was still asleep.

RPSchmidt
02-19-2019, 09:44 AM
On another note; I added a Blackbody Radiator to the node setup of the OpenVDB, which improved the overall appearance. I saved it and closed the file.

Now, when I try to open the file, I get an critical crash error popup.

Is there any way to get this file open, or have I lost the file?

Tobian
02-19-2019, 12:17 PM
Ouch! Hope you reported that. Hmm, trh and Import the items maybe? You could possibly delete the node using a text editor, but that's not very user friendly

RPSchmidt
02-19-2019, 12:34 PM
Ouch! Hope you reported that. Hmm, trh and Import the items maybe? You could possibly delete the node using a text editor, but that's not very user friendly

I wish I could report it, but I can't from the system it happened on.

Right now, I'm still using 2018.0.0; for some reason, it has been super finicky when working with OpenVDB sequences. Sometimes it does just fine, but if you make the slightest change, the file crashes and you're back to square one.

Ah well. I started over, for lack of better options.

RPSchmidt
02-21-2019, 06:58 AM
Okay... this is very frustrating for so many reasons.

First, I have an OpenVDB sequence of 500 VDB objects. I create a null, add the sequence to the Emission, Scattering, and Absorption channels.

I set the Emission channel for fuel and the color to 255 054 000. I animated the scale starting at frame 35 going from 1 to 0.

I set the Scattering Channel to density and set the scattering color to 000 000 000. The scale is 1.

I set the Absorption channel to density and set the absorption color to 000 000 000. The scale is 1.

The explosion looks good; the colors seem right, the amount of smoke seems right.

Two things are killing this for me.

1. I turned on indirect sampling in the Volume Integrator and Radiosity is on; but I am still not getting any light coming off of the VDB object. The explosion is set directly next to a building in an area with some shadow and there is zero orange/red light being cast onto the building. Again, not sure what I am doing wrong here.

2. I set a single frame to render and it went from 5 hours to 24 hours to (coming in this morning) 254 hours to render. I'm on a dual Xeon ES640 2.67GHz system with 48gb of RAM. What the heck!?

The building is fractured but I baked out the MDDs for the fracturing and then just brought the fractured building in and applied the MDDs to it. There are no additional dynamics being calculated (that I know of).

A single frame of the building destruction renders by itself in about 3 minutes. Only parts of the building were designed to fracture and "explode". Total, there are only 240k polygons in the model, fractures and all.

As mentioned, this is a 500 frame animation and I obviously can't spend 254 hours per frame to render it.

What the heck is going on here? Is there some way that I can get this to speed up? What (out of the many things) am I doing wrong?

As mentioned earlier, I am using Lightwave 2018.0.0

Thanks in advance for any advice / support / suggestions!

Thomas Leitner
02-21-2019, 08:33 AM
...
1. I turned on indirect sampling in the Volume Integrator and Radiosity is on; but I am still not getting any light coming off of the VDB object. The explosion is set directly next to a building in an area with some shadow and there is zero orange/red light being cast onto the building. Again, not sure what I am doing wrong here...

Hi,
to lit your sourroundings with emission of your VDB you need to enable Volumetrics (Render Properties/Volumetrics tab), GI and Sample Backdrop (Render Properties/Global Illumination tab). To lit your smoke with emission of your VDB you need Indirect Sampling (Render Properties/Volumetrics tab) too.

ciao
Thomas

RPSchmidt
02-21-2019, 09:48 AM
Hi,
to lit your sourroundings with emission of your VDB you need to enable Volumetrics (Render Properties/Volumetrics tab), GI and Sample Backdrop (Render Properties/Global Illumination tab). To lit your smoke with emission of your VDB you need Indirect Sampling (Render Properties/Volumetrics tab) too.

ciao
Thomas

Thanks for the reply, Thomas. All of those are on; my default render settings use all of those settings except for indirect sampling, which I already turned on.

Thomas Leitner
02-21-2019, 10:01 AM
Thanks for the reply, Thomas. All of those are on; my default render settings use all of those settings except for indirect sampling, which I already turned on.

One more thing: Ray Recursion Limit must at least be 2.

ciao
Thomas

Thomas Leitner
02-21-2019, 11:15 AM
Thanks for the reply, Thomas. All of those are on; my default render settings use all of those settings except for indirect sampling, which I already turned on.

It is very difficulte to find the "missing link" without a real scene. So I loaded the "OpenVDB_Explosion-Blackbody_Radiator_Node.lws" scene from the LW18 Content and added a ground plane. I enabled GI, Sample Backdrop and Affected by Volumetrics and it worked: the ground plane was lit by the VDB. Maybe it helps to analyze this scene.

ciao
Thomas

RPSchmidt
02-21-2019, 11:34 AM
It is very difficulte to find the "missing link" without a real scene. So I loaded the "OpenVDB_Explosion-Blackbody_Radiator_Node.lws" scene from the LW18 Content and added a ground plane. I enabled GI, Sample Backdrop and Affected by Volumetrics and it worked: the ground plane was lit by the VDB. Maybe it helps to analyze this scene.

ciao
Thomas

I will give that a try; although one of my other issues is that I can't add the blackbody radiator node; as soon as I add it, it crashes Lightwave and the scene can't be re-opened (it crashes the scene file).

I wish I could add a scene file, but I just don't have a way to do that, unfortunately.

Tobian
02-25-2019, 08:54 AM
Stupid question, but did you try it in 2018.0.7? If you're getting a crash, it may have already been fixed.