Maya VFX Series: Burning Woods | PART 1

hello everyone this is reza welcome to another video of effects series in maya [Music] in this video we are going to explore how to set a wood material on fire now we've already discussed fire with some basic attributes in a previous video but i thought it would be a good idea to show you how to create fire in a larger scale and with the material that we specify and it has an impact on the way that the fire rises and the fire behaves so let's get into it really quick before i jump into maya and get some work done i just wanted to show you some reference images so we are going to focus on wood burning wood would be the focus of this tutorial now you can see every time you're dealing with burning wood we always get particles scattering around and these are part of the ashes rising up now you can see the flame or the fire itself is very crisp and take good look at the coloration we have orange we have red and we also have almost white color over saturated color we try to achieve that and include that coloration into our work today here's another example we have depth of field that's correct so the background is a little bit blurry but again the takeaway from this image is not every part of the object is on fire so some part of it we have flame the other part may not have any fire on it which is quite important another burning wood example so we've got a few big logs and you can see some part of the log is on fire the other side may not have any effect this is a good example that because that shows that pocket holes that black areas where the fire gets quite wild when it's it rises so again when we produce the pattern for the fire we want to keep that in mind again every time you create fire and the material is wood that is burning we do tend to get these particles and we are going to address that in this tutorial now back to our reference but this time bad examples they're not necessarily bad photos that might be quite artistic and quite enjoyable to watch but may not be ideal or the best pick as reference for example shutter speed can play a part in the flame being a little bit blurry or stretchy the coloration is still quite useful but not the pattern the pattern is not accurate look at this photo for example yes we do see some really nice lighting around the scenery looks good the particles we do see but there's not much fire we can see there is not much pattern everything is almost white especially low dynamic range images usually don't help and we end up having an image with practically no details so be mindful of that when you search for reference all right back to maya so what i have is 175 frames and it's 25 frames per second and i've got a simple very very simple model and there's really nothing to it i want to set this would on fire if i were to look at the uv maps so if i go to uv's uv texture editor you can see everything is nice and clean you can even take it a bit further create textures for the metal part i didn't really do that because the purpose of this content or this video is to focus on fire but you can really set some time aside and work on the textures and make them look as realistic as possible i've got a camera with a very subtle zoom just to add a little bit of drama to the whole thing but nothing too complex or specific now i'm going to start with a model select the model go to effects menu set and then i go to fluid 3d container and open the 3d container i'm going to reset the settings and the only change i would like to make is not to have emitter because well my emitter is going to be the material that i modeled and i'm going to go apply and close well the next obvious step is to make this as our emitter so with that selected we are going to go to fluid add edit content and emit from object if i go to the option box make sure that the emitter type is set to surface but again if you select no emitter when you create a container then this emitter type will switch to surface when you select an object now emitter type we can just call this fluid emitter emission cycle set to none and again all these measurements and numbers we can deal with that later now you can see i'm getting an error here simply because when you select from an object you always need to select the container as well and when you do that you're not going to get any errors now right off the bat we see that if i expand in the outliner fluid emitter has been generated and if i go under basic emitter attribute the emitter type is set to surface with the rate of 100 percent now i'm going to select the fluid container itself to put some basic measurements in place and make sure this container can encompass the whole geometry i might actually switch to perspective for clarity so if i zoom back i probably need a 20 to 20 to something like 30 and i can move the container up and feel free to even exclude the uh the legs for the bench because there won't be we won't be setting them on fire but if you would like to have them that's fine too now uh one thing that artists do use and it's very common is they set boundaries and especially for boundary wide they set it to y minus because they don't want the fluid to go in the opposite side in minus y usually this situation is when you have a ground floor then you really don't want the fluid to penetrate and go in but for now if there is a bench and there's a gap in here if there's a little bit of fluid coming in negative y and comes back up that's fine we don't need to really to be too worried about that now i'm just going to make sure that i have a little bit of room in here there is a tad a room here to make this even smaller we are going to use auto resize so we really don't need to be too big or too generous about the space that we are using i think something like that should do just fine you always leave some room for the fire to to be able to rise and to have patterns if need be but for now this gets the job done just fine i'm going to switch back to camera now next is to think about what type of content we want so we definitely want density we want velocity to have that swirl and we definitely want temperature so i'm not going to set it to static grid always choose dynamic grid if you're aiming for dynamic simulation and gradient is just again for static effects such as fog or god rays you may want to use gradient but for moving fluids dynamic grid is the way to go now if you have burnt gasoline or some other complementary materials for the fire then feel free to use fuel as well it's just a burning wood we're not using any gas or petrol to set the bench on fire so that is really not needed okay scrolling down i'm gonna go to display and set the bounding draw to none before i do that i can even increase the base resolution to something like 50 and here's the thing that some artists do ask why we're not getting the representation every time you change the base resolution you have to rewind and as soon as you do that you see the effect so i'm just gonna go and set the boundary draw to none you can set it to none or i can actually use bounding box so i still can see the container i don't want to see the grid underneath it can be a little bit distracting next is to pay a visit to dynamic simulation window now in order to use this window you need to make sure that in contents method the attributes or the contents that you're using should be set to dynamic grid for example if i set the velocity to off all of a sudden you see some of these attributes will grade out so make sure that whatever you would like to use in content method is set to dynamic grid to have full access to the all the attributes that this rollout has to offer and that's a very important rollout now the one that i would like to change always when i deal with fire is a damp i'm going to set that to 0.25 you got to be very careful with the number that you put in here for example a damp of 0.5 may seem small but it's actually a very high number because what damp does it suppresses the flow of your simulation now every time i use fire if i want to get a very wild looking fire i use high detail solve to all grid and this is something again that i will i discussed in details in the previous fire tutorial that i made on youtube so feel free to check that so this option reduces diffusion of density gives you crispiness gives you a fire with a more velocity in it and of course to complement that effect i always increase the sub steps so i'm going to increase sub steps to 2 and that attribute specifies the number of times the solver performs calculation per frame so it stabilizes the simulation or especially if the fluid you have is fast moving then you definitely need substance i mostly use substance for cloth simulation on a character but again little bit of substeps for effects like fire can still be quiet useful now solver quality is very important with the fire effect that we're going for i'm going to start with 150 but i will increase that to something around 250 or even 300. every time you lower solvable quality so if i were to lower even 20 to something like two then it reduces the details in your simulation and adds more diffusion which is opposite to what you want when you create fire when you create fire you always want more details because the one that if you remember in the references that we showed at the beginning of this video fire is all about having details and if you remove that you probably end up having a solid color so higher solver quality is definitely one of the attributes that is recommended if you want to do this in maya now every time i change sub step and increase solver quality it's like a an automatic reaction i go and enable emit in sub step if you don't enable that then this won't be taken into consideration so be very very careful now simulation rate scale how fast or how slow your this fire you would like to be and i am going to actually increase that attribute to something like 2.5 this is a scaled base number so as long as your scale is exactly identical to mine this number works for you but if your object is massive or if it's tiny then this number definitely will not going to work for you so it's a scene scale base attribute now that should do it for now i can go back to this and make more changes for example one really good attribute that artists use is very tiny number of viscosity but again it really comes down to what caused that fire so burning wood especially dry wood we really don't need viscosity now moving to auto resize which is very very convenient attribute when on autodesigns dynamically resizes the 3d fluid container for you so you don't need to constantly worry about the boundary size or create a ginormous boundary size to cater for your fluid system now before i move on let's just take a look at the ugly result that we are going to getting because we haven't done much and the resolution is very low i just want to make sure that we are getting some actions here all right that's more than enough now you may have noticed that there is a problem here well apart from the base resolution i'm going to say to 75 50 is way too low the main problem is we are getting fire from everywhere so the entire model is now set on fire which is a little bit unrealistic especially i pointed that out the beginning of this video through the references we observed that sometimes it's not the case maybe there's a fire here but they may not be fired there not to mention if i simulate this even with the realistic looking fire you barely see what is causing it you barely see those logs because all you see is just fire which is not realistic and it's one of those things that as soon as someone looks at it they know it's cg so we need to fix that we need to rectify that and that is the main highlight of this tutorial if you were to compare this tutorial with the previous one that we took a look at now to do that we need to go to our emitter now in the emitter in the fluid attribute section we can say please include density please include heat please include fuel well we don't have fuel so we can just say no emission but with density and with heat we have a way to say i would like this emitter to have heat and density but based on the map that i specify and that's the true power of having this rollout so i can literally go and say select a file black areas don't emit any density and no heat white areas please go ahead and emit density and heat to the specific attributes that i want and you can go ahead with that you can even use filter type to add more blurriness to it if you want now if i go to hypershade just going to resize the hypershade so we can see it i can just name this mask emitter so we can kind of identify it and if i select the emitter from the outliner instead of going ahead and creating a brand new one you can actually with that renamed you can drag and drop the heat in here so you're using the exact same note for both emission maps don't create a brand new node it's just one extra node maya has to calculate now that's actually great that allows us to somewhat customize the emission through a black and white map now let's go ahead and reduce the fluid drop off to zero it just blurs the surrounding areas and i really don't want any blurriness that happens with the fluid that i'm working with now while i'm under this fluid attribute i can actually expand fluid emission turbulence and bring in some turbulence so it's just an internal force field that will be added to the container and the fluid that i have i can even go ahead and go full speed on this and make finer frequency for the turbulence that i have and of course i can add details which is a kind of a reflective intensity of a second higher frequency turbulence set to 1 would be a good number so having a detailed turbulence set to one always helps so if i go back and just play you can see now i can just pause or somewhat stop the simulation we can see that not every part of this fluid is on fire now you can see for example this area does not have any emission this area doesn't have any emission and the fact that it's a bit blurry it shows us that we eventually need to increase the base resolution that blurriness comes from the low resolution we have but for now we know that the emission map we have is working now let's go to the fluid container and continue with our changes so now it's a very important one content details and i explained this menu in the other video i'm gonna go through this again so density scale how thick you want this uh density to be usually 0.5 is a good number unless you have a very specific reason to change it buoyancy how fast it's going to rise and i'm just going to go with the three again this is scene scale base don't just copy those numbers make sure that those numbers can work with the scene scale you have now dissipation how fast you want fire to dissipate so i'm just going to set it to 0.75 it's not really a high number you can go over one easily now another change we would like to make and that's rather an important one and without that your fire lacks that realism is gradient force in here we definitely would like to have a positive value i can go up to 20 considering my scene scale i will start with 15 and i feel like that number should work but i'll keep an eye on this and if need be i will increase that value but definitely explore that it really helps the velocity of your fire and the way it rises and behaves speaking of velocity we need to add a little bit of swirl in there it's one of those things that you always drop in when you have fluid and definitely going to work for us and let's do a quick play blast now let's have a look well the overall movement is not too bad just keep that in mind that we were looking at mostly density we haven't had a chance to tweak the temperature just yet which would be to do next okay so let's keep going let's uh continue with the content details density is done turbulence we add a little bit of swirl i can actually go ahead and increase that swirl some more i think we it you know every time you have swirl if you think it's there's a little bit of room to push always do that so temperature scale obviously for fire one is not enough i may go even up to two points well let's see keep it at two and then we'll make some adjustments later and then buoyancy definitely needs to be a lot higher um temperature tends to be much slower than density if you put this value buoyancy for temperature if you set the value for density 25 then you see a really really speedy rise whereas a buoyancy of 25 for temperature is not really big of a deal dissipation um 0.75 won almost the ballpark of the value we set for density works for dissipation as well we want just the tad amount of diffusion again 0.1 i found is a bit too high so i'm going to go with .015 and see how we go turbulence if there is a chance to add turbulence internally in temperature why not i always want to do that so turbulence of 15 that number might be a little bit high but again we'll see and noise uh 0.2 let's start slow and then we increase if we need that before i get into the shading part one thing i noticed in the play blast was the fire was just going up and that's rather boring so i would always envision if there is any fire there must be a gust of wind or something and that adds to the fluidity or the pattern of the fire that we have makes it certainly look more interesting so while we have this fluid container here i'm just going to go to field and solver and add a secondary gravity and i'm going to call this a wind because i want that to act as a wind i'm looking at the direction minus z is working for me attenuation please set that to 0 because the default value attenuation is one definitely messes up with your force field if you really want that to have an impact on the entire scene you should not have any attenuation so with that in mind and with the fluid container selected i'm gonna go and create now this wind is ready to go i'm just gonna rename this to wind force field and i'll even make it more interesting i would like to keyframe this magnitude so it kind of constantly changes strength and magnitudes and the fire will react to it and this is something that we kind of did in the previous video as well so let's go ahead and do that i'm going to make the default 10 i'm in frame 1. i'm going to right click on it and set a key then i'm going to go to frame let's say 20 and we say all right i want that to be still 10 but then all of a sudden in frame 30 i want to increase the value to 30 and set a key you can even have the auto key on i have the other key on i really don't need to right click on it but just for demonstration purposes i will do that i'm going to go to frame 37 and say still have that 30 value then i'm going to go probably to frame 75 and there is no rehearsal behind this just randomly go and change it and i can do it through an expression and i can do it through like a hand created keyframes since we've got only 175 then doing that is just fine so the value we had was 30 now reduce it to 10 maybe and let's go to frame 80 mix it up a little bit and all of a sudden in only 5 frames we jump to 30 and then i'll go to frame 120 and back to 10 keep that until frame 150 have 10 and in 160 we would like this to jump from 10 to something like 40. and the reason that you see this like a snow effect because you never want to scrub throughout your time slider when you have fluid simulation unless it's been cached and i expect you to know that but if you don't know that that's okay so you go back with that then it definitely is going to give us a better result let's uh go and do another play blast just to make sure that there's nothing crazy going on with that force field i don't want to do 200 steps and then have a look because with that if there is any problem you don't know where to look so i'm just going to start two and do a another play blast okay i did a play blast for 110 i think that should do it more than enough and now you can see that wind does have an impact you can see minus y which is towards the right direction it really pushes the fluid you don't want that to be too obvious at the same time you really don't want the fluid to just rise straight up so that kind of happy medium very subtle movement definitely helps okay that is good let's keep going i'm going to select the fluid and temperature is done then let's see what's next definitely shading and that's a super important attribute one of the top three if you name three important rollouts with dynamic simulations especially fire one of them is always shading now transparency starting with that number i'm just going to probably make this just a tad thicker well when i increase that value i'm actually making it thinner just so you know if i go all the way to zero then you see a completely opaque fire if i crank it up to one then you have an invisible fire if there is such thing then to see the temperature i don't know that's really odd the way that this operates in in maya but to see temperature you always need to reduce this and look now we see the true value for temperature i'm going to use the low value like .003 maybe and we want that input bias set to zero definitely you don't want to mess up this temperature value you have now comes down to probably the most important rollout in the shading section and that is incandescence incandescence shows how you would like this fire to be shown sometimes you have a little bit of gas in it the fire turns blue then you need to reflect that sometimes you burn gasoline you want a thick black smoke coming out of your fire you need to tweak that here sometimes you're not burning dry wood like i do in this scene you're burning wet wood and that produces a very thick white smoke then you need to make sure that it's in there as well so i'm just gonna experiment with few values and mute my microphone feel free to follow along or come up with your own rendition based on the reference that you are observing all right now need to make sure that the incandescence input is set to temperature so this graph will be applied to the temperature and input bias for that is also set to zero now i'm gonna go ahead and tweak the opacity as well and that kind of um gives you the freedom to give this scene more or less amount of smoke you can see if i go too far with some areas for example here all of a sudden i'm creating a very um kind of rich fire with so much black smoke so it's again there's no right or wrong way there's no way for me to come up with the formula it's just your taste and how you would like to see the result coming out so i'm just kind of experimenting with this i tend to have spikes for lack of better word a little bit of input bias so maybe point zero five you can go even four to have fewer pocket holes and output you want that output to be temperature and yeah maybe if you want to go and change the interpolation to smooth for some of these guys not for incandescence but for opacity feel free to do that now i can just do a very quick render and you can see for just a base resolution of 75 it certainly works but again i do see voxels even the blockiness is not quite pleasing but what you should look at is the gradient of colors the variation of the colors i have a little bit of smoke not too much not too many and i have white spots in here and here which you can even intensify if you want and that's what you should be looking for at this point now speaking of resolution let's go ahead and add a little bit of resolution and see what we're getting before i do that i'm going to go to self shadow and add that so i get a little bit of ambient occlusion as well so ambient color i'm gonna get that color in all in all it helps with the aesthetics now with the base resolution i i usually don't mess around i always set it to something like 350 or maybe 400 yes it takes time but that's what you need to do to get a really crisp result look also i go to fluid emitter and increase that heat voxel from 1 to something like i don't know 1.625 it gives you more heat and it intensifies those bright areas you don't want that to be too bright at the same time you really don't want fire to look just orange because it's not realistic now i'm going to rewind i'm going to select the fluid before i do anything i would like to cache it out so i'm going to go to encash create a new cache maya fluid option box and i'm going to just make sure the time slider is selected if you have 1 to 175 that's great one file per frame you don't want to create one file for all of it and everything should be ticked here and you go create now i will see you after the caching process is finished now it took few hours but the cache has been finalized so i can actually click on each frame and the fire updates itself it's not going to turn to that powdery look because everything is now been baked into physical files and it gives me the the ability to be able to kind of navigate to different parts of the time frame without messing things up now if i go and give it a render i should be able to see something decent with higher quality something that i can use now this is great my intention is to take it a little bit further and give you the freedom of adding particles to that as well let's put that actually on a layer so we can render this i'm going to put a fluid into a layer so just gonna create a collection i'm gonna call that collection fluid add my fluid simulation here you can even have another collection if you want collection call this environment light i'm gonna bring my dome light in here and i'm gonna make the collection filter as light so that allows you if you want to just render the fluid without any props in the scene which to me is pretty good when you go to render settings you can even set up this lender layer rather than master layer and only get the fire to render and that's actually what i'm going to do and then in the next video we are going to finalize this and we are going to add particle system in there and make this integrated and part of the fire simulation that we have we're going to render it out and we're going to have a look at the final result thank you very much for tuning in and see you in the part two of this video

Channel: SARKAMARI

Views: 6,979

Keywords: 3D fluid Container, Fire in Maya, FC in Maya, Fluid Simulation in Maya, Autodesk Maya Tutorials, Reza Sarkamari

Id: PFQFY_vpodI

Length: 39min 6sec (2346 seconds)

Published: Mon Jul 27 2020