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Thread: OpenVDB not rendering?

  1. #1
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    OpenVDB not rendering?

    So I created an explosion in Blender and baked out all of the physics to OpenVDB.

    Then I took that into Lightwave to incorporate into a building destruction scenario.

    I set everything up with nodes and the explosion shows up clearly in VPR.

    BUT... when I render it, there is nothing there. The render takes forever as though something SHOULD be there, but it doesn't actually render the explosion.

    Not sure what is going on. Checked my render properties and I didn't inadvertently select anything that would cause the VDB to be invisible to the render camera.

    Any ideas?

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    Super Member JohnMarchant's Avatar
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    Does legacy volumetrics effect this. TFD has to be set to legacy volumetrics, not sure about Blender exports.
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    Quote Originally Posted by JohnMarchant View Post
    Does legacy volumetrics effect this. TFD has to be set to legacy volumetrics, not sure about Blender exports.
    Hmmmm... not sure. I wouldn't think so, because it is using the OpenVDB object. That's new in LW2018, so I wouldn't think that it would be dependent on legacy volumetrics.

    This is my first foray into using OpenVDB sequences from Blender though.

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    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by JohnMarchant View Post
    Does legacy volumetrics effect this. TFD has to be set to legacy volumetrics, not sure about Blender exports.
    No..blender imported vdb should render fine, no need of legacy volumetrics, itīs just for rendering the direct generated volumetrics from TFD, if you bake out turbulenceFD to VDB...there is no need for legacy either.

    I would suggest set the imported blender vdb file in Lightwave as a scattering channel set to density, and emission to density as well if itīs only smoke, if it is carrying a temperature channel, you would want to set emission to that or flame.

    In blender...do not compress the simulated vdb files in the cached options, it could screw up the channels for fire and flame.
    Note..make sure to enable volumetric shadows in vpr if you use that as a previewer.
    Depending on initial density simulated in blender, you may want to increase scattering scale a bit.

    Check the link to a thread covering a bit of this..for more info...https://forums.newtek.com/showthread...ender+open+vdb


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    Quote Originally Posted by prometheus View Post
    No..blender imported vdb should render fine, no need of legacy volumetrics, itīs just for rendering the direct generated volumetrics from TFD, if you bake out turbulenceFD to VDB...there is no need for legacy either.

    I would suggest set the imported blender vdb file in Lightwave as a scattering channel set to density, and emission to density as well if itīs only smoke, if it is carrying a temperature channel, you would want to set emission to that or flame.

    In blender...do not compress the simulated vdb files in the cached options, it could screw up the channels for fire and flame.
    Note..make sure to enable volumetric shadows in vpr if you use that as a previewer.
    Depending on initial density simulated in blender, you may want to increase scattering scale a bit.

    Check the link to a thread covering a bit of this..for more info...https://forums.newtek.com/showthread...ender+open+vdb

    Thanks, prometheus.... I went back and checked my scattering and absorption channels and made those changes, then also changed the OpenVDB node to use velocity and that worked like a charm.

    I did output them with compression, though... so I think I will go back and bake it again without compression.

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    RETROGRADER prometheus's Avatar
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    You could also use blackbody radiator node instead of your own manual gradient, in this case I applied it the emission channel and a texture editor node, which I think was overcomplicating it, you should be able to do this within the main node editor I think.

    Quality wise? well you got the three various interpolation modes, but you need high resolution simulations for it to render really smooth in Lightwave open vdb.
    In houdini there is a smoothing vdb node, I do not think there is a similar tool in blender or something in Lightwave that would help with that in a similar way, so High res simulations for smoother results.
    The images I posted as showcase of the nodes are way...way to small in simulated resolution.

    Imported blender vdb files can crash if you scrub the timeline to zero, so beware of that.


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    I did use a blackbody radiator and once I got the separate channels set up correctly, the end result was very nice.

    Now to see how the entire scene render looks!

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    Okay... things are not working out.

    First, I created an explosion in Blender following a tutorial. In Blender, the explosion looks great. It was created using Smoke and Flame.

    I baked out the OpenVDB sequence.

    When I create my OpenVDB object in Lightwave and use my sequence, I am missing practically everything that has to do with fire in the Emission / Scattering / Absorption channels.

    For example, I am missing flame, flame low, fuel, fuel low, heat, heat old.

    All I have to work with (essentially) is density and velocity.

    Not sure what I did wrong; although I am using a slightly older version of Blender (2.78).

    In addition, a single frame is taking a horrifically long time to render; a frame I started last night wasn't even finished this morning.

    Now granted, it's on my work comp which is a tad old (dual Xeon 2.6ghz processors, 16 threads)... but when I render the sample OpenVDB scene in the Lightwave content, it renders very quickly.

    I must be doing something horribly wrong, because this seems ridiculous.

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    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by RPSchmidt View Post
    Okay... things are not working out.

    First, I created an explosion in Blender following a tutorial. In Blender, the explosion looks great. It was created using Smoke and Flame.

    I baked out the OpenVDB sequence.

    When I create my OpenVDB object in Lightwave and use my sequence, I am missing practically everything that has to do with fire in the Emission / Scattering / Absorption channels.

    For example, I am missing flame, flame low, fuel, fuel low, heat, heat old.

    All I have to work with (essentially) is density and velocity.

    Not sure what I did wrong; although I am using a slightly older version of Blender (2.78).

    In addition, a single frame is taking a horrifically long time to render; a frame I started last night wasn't even finished this morning.

    Now granted, it's on my work comp which is a tad old (dual Xeon 2.6ghz processors, 16 threads)... but when I render the sample OpenVDB scene in the Lightwave content, it renders very quickly.

    I must be doing something horribly wrong, because this seems ridiculous.
    First...save your blender file, so it is caching correctly, Ivé run across that as well about loosing the temp, flame etc, I think it has to do with the cache format you set..have to check within a couple of hours, if you donīt solve it I can probably
    advice then.

    Check your volume step size if you have a large scale sim, turn this step size up till it renders faster in vpr, also check other AA settings, turn of radiosity for starter.

    Iīll try to record something soon.

  10. #10
    Dreamer Ztreem's Avatar
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    You could also bring your LW scene to blender and render everything there.

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    Quote Originally Posted by Ztreem View Post
    You could also bring your LW scene to blender and render everything there.
    Nope. I don't know enough about Blender to fix any potential issues and all I want is a simple explosion for an already constructed bullet simulation.

  12. #12
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by RPSchmidt View Post
    Nope. I don't know enough about Blender to fix any potential issues and all I want is a simple explosion for an already constructed bullet simulation.
    In blender...
    Checking..hereīs what to try, do not load the very first vdb file from blender, use number two..otherwise it most likely skips the flame and heat channels....so just change your vdb file loader to load from number 2.

    make sure you have smoke and fire material as well, I would suggest to install 2.79.3 which have the great principled volume material to make it easier to setup fire and smoke.

    Make sure you have selected fire and smoke in the fluid emitters flow/flow type.


    If you have a cuda card good enough, using blenders gpu will render volumetrics much faster than Lightwaveīs cpu volumetrics(unless having a very very fast cpu), both cycles previewer and final renderer, and within blender you can change the scenery both fluid and dynamics at once.
    Once imported as vdb In Lightwave, you are limiting yourself and the render.

    The fracture tools and beaviour of fractured stuff in blender is also great in the sense that it doesnīt jitter, unlike a lot of other sim tools, and you can create fracture dust debris particles and emitting fluid smoke from it (fracture build)

    I mostly use the spacebar and run quicksmoke for any item in blender I want to simulate fluids from, and change flow type to fire and smoke, instead of manually adding each item such as container/domain etc.

    I think you should invest time in learning blender, itīs a great helping tool ..If you do not have the resources to get TurbulenceFD, and many many other things, turbulenceFD currently do not have a built in
    PBR volume shader, so in that sense it may fall short in render realism against blender, Unless you convert the simulated TFD result to VDB format and load back in to the scene.

    VDB in Lightwave has been asked for years, but maybe it still is a bit thin in implementation, itīs a helper if you absolutely need to render out in Lightwave for some reason, but if original sims in other software can be rendered both with better quality and faster, And keeping the sceneīs dynamic flexibility which VDB doesnīt have..why not?

    Edit...multiscattering in Lightwave volumetrics with PBR doesnīt seem to working good enough, in blender it yields better results...and trying with turbulenceFD old legacy volumetrics ..it recalculates quite a while for each change you do in the shading..just too slow in my opinion.



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    Quote Originally Posted by prometheus View Post
    In blender...
    Checking..hereīs what to try, do not load the very first vdb file from blender, use number two..otherwise it most likely skips the flame and heat channels....so just change your vdb file loader to load from number 2.
    I'm just loading the VDB sequence into the null object with OpenVDB applied. I did try to change the Sequence settings to start from the second frame (I saw you mentioned that in another thread) but it kept crashing LW.


    Quote Originally Posted by prometheus View Post
    make sure you have smoke and fire material as well, I would suggest to install 2.79.3 which have the great principled volume material to make it easier to setup fire and smoke.

    Make sure you have selected fire and smoke in the fluid emitters flow/flow type.
    Unfortunately, I don't have any installation permissions on my work computer and getting them to update anything takes forever and a year.

    I did double-check my simulation in Blender; I do have the material set up and added an emission material as well. I also double-checked my emitters' flow type.

    The simulation looks fine in Blender; Shift+Z shows the volumes and the OpenGL shows it as well. When I take it into Lightwave, the simulation is there and plays, I just don't have all of the channels available.

    Quote Originally Posted by prometheus View Post
    The fracture tools and beaviour of fractured stuff in blender is also great in the sense that it doesnīt jitter, unlike a lot of other sim tools, and you can create fracture dust debris particles and emitting fluid smoke from it (fracture build)
    Yup, but as I said, I already built the entire simulation (minus the explosion) in Lightwave; I even rendered out a 500 frame test and it looks great! It's just missing an explosion.

    I was holding off on trying to get these bozos to buy turbulenceFD until the new version came out. Even if I started the process today, I would be lucky to get it by next year.

    I really appreciate the help and suggestions!

  14. #14
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by RPSchmidt View Post
    I'm just loading the VDB sequence into the null object with OpenVDB applied. I did try to change the Sequence settings to start from the second frame (I saw you mentioned that in another thread) but it kept crashing LW.




    Unfortunately, I don't have any installation permissions on my work computer and getting them to update anything takes forever and a year.

    I did double-check my simulation in Blender; I do have the material set up and added an emission material as well. I also double-checked my emitters' flow type.

    The simulation looks fine in Blender; Shift+Z shows the volumes and the OpenGL shows it as well. When I take it into Lightwave, the simulation is there and plays, I just don't have all of the channels available.



    Yup, but as I said, I already built the entire simulation (minus the explosion) in Lightwave; I even rendered out a 500 frame test and it looks great! It's just missing an explosion.

    I was holding off on trying to get these bozos to buy turbulenceFD until the new version came out. Even if I started the process today, I would be lucky to get it by next year.

    I really appreciate the help and suggestions!

    If that is the situation, you need to stress to your company that you need that update, or you canīt do your job..if they do not listen...drop the job, either the company or the current work ahead.

    Donīt mess with the sequence options, just unload the vdb file by setting it to none, then load the vdb file 00002 or something, not the 0001 file..so you shouldnīt have to mess with sequence options.

    Fine..you have the material and other settings right..again, itīs most likely the case that you have loaded the 00001 sim, as I sadi before..load the 00002 sim and ..not with the sequence options.

    I have had so many issues with TFD and Jascha has been so silent that I am not feeling confident in investing in TFD, as well as Lightwave overall as of latest release, I do hope Lw picks up speed..but this time I can not join in
    for the current lw release.

    Blender offers fire and smoke in opengl at once, and faster and more realistic render, what it may not be able to compete with compared to TFD, that is perhaps simulation speed and huge voxel cached sims, and also...TFD has more control over finer turbulence settings I think.
    Octane for lightwave may help overcome some issues in TFD rendering though.


    AS for already created lightwave bullet sims, you can mdd export the lightwave bullet scene, and apply blender fire and smoke on it in there, though you need to be aware and now how to flip the mdd file axis correctly, If I only had time to record it..could
    take a print screen on it maybe.
    So itīs not necessary to create fracture and do that stuff all again in blender, you should be able to go this way with mdd and be fine.

    The problem is that you would have to learn setting up nodes for fire and smoke in blender if you are not allowed to install 2.79.3...since itīs that version that has the Principled volume shader, with that shader you just need to raise blackbody intensity for the fire to kick in.

    In my sample vid I just showcased how to use two of the same principled material to push the density scattering as if it had more flames in the density.

    Other alternatives would be to use real fire clips if you can find good ones, and it may by todays standard look a little fake if youīre not good at compositing.

    or use particles and hvs, but then you loose realism by todays standard.

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    Dreamer Ztreem's Avatar
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    Quote Originally Posted by RPSchmidt View Post
    Nope. I don't know enough about Blender to fix any potential issues and all I want is a simple explosion for an already constructed bullet simulation.
    I know the feeling been there a year ago, now I havn’t started LW in months. You can render the explosion in blender and comp it with you lw render. Best would ofcourse be to get the vdb file to work in lw. Good luck!

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