The HIDDEN Settings for VDBs In Unreal Engine

vdbs are working in Unreal Engine here's how to get them working quickly plus some super secret tips that will make them look as good as possible you're not going to hear these anywhere else the first thing you're going to need is the free VDB Shader from Pixel lab this thing is really good gives you full control over density temperature emission I've linked to it in the description below this is going to save us from riding our own Shader so let's start a new Unreal Engine project I did do this with a game project to start with but unfortunately when you have a VDB in your scene and you want to look at it with path Tracer the whole thing crashes you don't want to get that far down the line and then hit this problem use a film template with raate tracing enabled now that we're in we just want a really basic lighting setup for our scene so we can view our vdbs nicely so remove all of the usual stuff from your outliner and go to your window menu to the environment light mixer and then just click all the buttons now we want to add the free VDB Shader that we got from Pixel app so if you go to your downloads where it should be you'll find a zip inside the zip you're looking for a folder called pixel labore VDB undor Shader copy that and then we're going to go to our project folder into our content folder and then paste that Shader folder now that folder will appear in your content browser inside unreal go to your ad menu and under all classes search for heterogeneous volume click that and it will be added to your scene with it's selected you'll see in the details panel there's an area where a material can go that's where we're going to drag our pixel lab VDB Shader you drag that across into your details panel now we have a VDB in our scene now the lovely folks of pixel lab have given me a discount code for you guys that's just on screen right now and in the description below that will give you 20% off anything from their library and it's a big Library they've got some amazing materials terrains they even have this heat Distortion and blur pack for Unreal Engine which I'm really interested in myself anyway cuz I've tried to build one from scratch with mixed results but this one from the video looks so much better than mine so I'm really tempted by that they also of course have vdbs they've got explosions clouds mod fire I'm going to be testing out a bunch of these in this video and you're going to see some really cool renders of them so if you're interested in anything from Pixel lab feel free to use the link in the description and the code which will get you 20% off I've got a fire asset that I'm dying to test out it's an animated VDB so it's got a single VDB file for every frame in that animation to import it I'm going to create a folder in my content browser in on real engine call it VDB just to be organized then I'm going to go to Explorer where my VDB is saved select the first file frame number one and then just drag that across to your Unreal Engine content browser and then you'll get an import popup the density is going to be set to the red Channel you need temperature for this being a fire asset to be set to the green Channel under attributes a for some reason it always defaults to attributes B just remove it out of there then just click import and it will take a moment to import all of your frames and depending on the length of your animation it may take a little while once that's done you need to go to the pixel lab VDB Shader folder and inside there there'll be a folder called source file and inside there is a master material this needs to be duplicated so that we can create a brand new VDB if we wanted to keep our old one just change the name slightly I'm going to call mine fire and then open that material once you're inside the material just navigate and find the VDB file node this is where we specify which VDB this material is going to use so once you've selected that node you'll see a little drop down in the details there and you can just select the new VDB that we imported now that that's done you can just right click on your new master material and select create material instance this material instance can be dragged over into the material slot of your heterogeneous volume and you probably won't see anything straight away especially if it's an explosion or fire cuz they can grow over time and you'll be at frame zero so if you look in the details panel of the hetrogeneous volume there'll be a part where you can specify the actual frame that you're viewing but if you want to see it play back there's also checkboxes for play and loop that's looking pretty good if your goal is to use this in a cinematic then you're going to want to use a level sequence so you can send it to movie render queue to do this go to the top of the window and add a new level sequence once that's created and you've given it a name we'll also create a new cine camera as well and drag that cic camera into your sequencer we also want to drag in the hetrogeneous volume that we've already created into our sequencer as well in sequencer next to hetrogeneous volume you'll see a small plus button click that and select hetrogeneous volume component then click plus next to hetrogeneous volume component find frame and click that now we can specify what frame we're on at any given moment make sure your playhead is at the beginning and then type in frame zero and click the little key frame button but we want to do the same at the end so I'm going to move my playhead to 399 and type in frame 399 and it will play but by default the key frames we've set are busier key frames so highlight them both and then change them to linear now it will play at a constant rate okay we're getting into the details now so I did notice while playing around with this that sometimes translucent objects would render on top of a VDB even though they were placed behind them it's very easily solved by going into your translucent material whatever that might be whether it's glass or something else and just setting the translucency pass to render before depth of field problem solved so if your VV starts to disappear as you get too far away from it there's an easy solve and that's a console command which is r. hetrogeneous volumes. Max Trace distance the default is 30,000 but if you set it to like a million you should be good to go but if you need more just set it to higher really excited about this bit now so we're going to get path tracing working and we're going to fix all the quality problems you may run into in your console type in r. pathtracing do heterogeneous volumes and set that to one so that's all you need to do to get pth raising working with vdbs but now you're going to see something a bit ugly see on the edge of this fire VDB now you can see a pixelated Edge this was not here in lip mode but in past racing you can see this good news is this can be fixed with two console commands commands the first one is R.H hetrogeneous volumes. orthogrid do shading rate and the other one is R.H hetrogeneous volumes. frrom grid. shading rate these are set to four by default but if you set those to one that would be cinematic quality but having done that now you're probably going to see another artifact and as I Chang the camera angle in path Tracer you can see this now it's another kind of glitch in the viewport which looks like the FES disappear and coming back now the reason this is happening is because we've increased the shading rate on both of these grids but now we need more memory to display the VDB properly so there are two more console commands to fix this so one is these are really long r. heterogeneous volumes. athor grid. Max bottom level memory in megabytes and then r. hetrogeneous volumes. firstr grid. Max bottom level memory and megabytes both of these by default are set to 128 but if you change that up to something like 512 in this case but it really depends on the VDB it looks so much better look at that edge it's just so much nicer I'm really pleased with this now I did promise some cool renders so I've gathered together some awesome vdbs from Pixel lab I got this fire asset an explosion some smoke and an awesome nebula here you [Music] go main engine's Argo so it's nice to see vdbs working Onre engine and it does seem like there's some planned updates as well for 5.4 which address things like translucency shadows and Lumen as well as some maybe quality life fixes for path Tracer one of them I hope will be to actually expose these console commands to the details panel because doing it via the console is a bit of a pain to be fair that's all from me on this video I'll see you on the next one

Channel: Joshua M Kerr

Views: 8,860

Keywords: Unreal Engine, Unreal Engine 5.3, VDB, heterogeneous volume, heterogeneous volumes, vdbs in unreal engine

Id: W3nHmsIZR-0

Length: 8min 11sec (491 seconds)

Published: Fri Dec 01 2023