Introduction to Groom Tools | Houdini Tutorial

so good evening evening everybody my name is mark spevik i'm the head of 3d course leader at escape studios and uh the houdini tutor oh hi there joseph and uh so i'm going to take you through um this evening for the next hour so i'll give you an idea of what goes on on the um houdini course and we're going to do that through groom we're going to have a look at a little introduction to the groom tools within houdini um as you know we've got a series of webinars in houdini i'm doing one a bit later on in a month or so a couple of months to do with uh fluid large and small scale water effects with flip so you might want to come along to that too so just you know i'm going to give you an introduction to houdini so the idea of the taste today is to give you an idea of how the style of teaching is at escape and gives you an opportunity to also ask questions about the courses and also a little demonstration about some cool stuff that you can do on the particular software in this case houdini so you'll notice on the interface for zoom here you have a q a button and a chat button um it's better if you um put questions in the q a because those questions stay there and it's easy for me to answer them as we go along if you stick them in the chat they tend to get lost and i might not be able to get to your question so please um uh yeah so please make sure you put your questions in the q a so the webinar is we're going to go through the little bit and i'm going to try and leave sort of five or so minutes at the end to answer any questions about the course but of course as i go through if you want to ask any questions please stick them in the q a and i'll do my best to answer them as we go so i tend to answer the technical questions as we go and i save the questions for the course and content towards the end there so yeah please ask questions that's the important bit so i might have to cut my video feed as we go because it's quite processed and intensive and trying to stream videos and run houdini at the same time doesn't often work too well so if my video feed goes um don't worry about that you'll still be able to see my screen and hear me um have i shared my screen yes i have so hopefully you can see my screen here and uh hopefully you've downloaded the non-commercial version of houdini or you might have your own license which will be absolutely fine enough but what you want to do is if you want to follow along please fire up houdini and if you get left behind or you're a bit confused please type in the q a and i'll happily pause or go over stuff to clarify so um let's start them so i'm going to start with the default layout of houdini here and what i'm actually going to do is just pop up click on this little arrow here see the arrow goes upwards that will make this bottom pane large just to give me some more real estate in the network here so we're going to look at the groom tools which are pretty pretty awesome in houdini they've come in sort of the last few versions and really matured quite a lot and uh they're fairly easy to use and get some interesting sort of sculpt so i'm going to take you through some of the little techniques and major bits and pieces that you might be interested in to do that to get you started so the first thing i want to do is create some geometry obviously to make furry to give some hair to and as you saw from the uh the flyer for the uh to the uh taste today i'm going to be using the pig the test geometry pig so here at the object level we can hit tab and we can type test to see all the test geometry here and we can see our pig's head so i'm going to pop the pig's head in you don't have to use the pigs head you can use whichever one you want and what i'm going to do is i just want to modify this a little bit so if i dive inside we can actually see our pig's head geometry here i'm just going to add another node you can add nodes in houdini by hitting tab and typing match size and uh this is a nice new addition to houdini which will allow us to reset our object around the origin in specific ways i'm going to tap p for the parameter pane and this gives me the options here what i'm going to do is adjust the y position here to the minimum of the bounding box which is the bottom of the object that means it now sits on the grid perfectly so it's nicely aligned in the scene for this example it's not too important but it's a nice thing to have a look at i'm going to assume people have um opened up houdini before because it's only an hour and i want to talk about the groom rather than how to interface with houdini or interact with it so if you were to come the course obviously we go through the interface and all the buttons and the paradigm of procedural modelling and everything else you really understand the differences between houdini and other dccs you know um digital content creation softwares that's what dcc stands for things like maya and blender and yada yada because houdini works in a very very different way being a procedural software but again we explain those differences should you come along so but first we'll start with our test geometry pig's head now unlike normal houdini where you'd normally go inside the network and do stuff in sops the groom tools are in fact inside stops but we tend to interact with them mostly up at this uh object level so that's what we're going to do now fortunately for us as well there's some really nice shelf tabs to help us with our hair or our guiding for the groom and you'll notice there's three there's this hair utilities there's guides and there's guide brushes we're going to start with the hair utilities and as we make it i'll explain how groom works and it's the same um whether you use x-gen or fuzzy ball or you use um houdini's groom the principles are pretty much the same which is good so once you kind of develop some skills of grooming in one of them you can easily apply those into the other softwares they'll have a very very similar tool set and they work in pretty much the same way and the way that is is as you can imagine on a hairy head you might have thousands and thousands of hairs you really don't want to sculpt and move all those around so we use guide hairs to do that so we'll have a low res version these guides which we can manipulate and those guides will generate the full groom later on and that's true of pretty much most grooming softwares because otherwise just trying to deal with all those fine hairs is almost impossible so that's what we'll do we'll create some guides first we'll style the guides and then we'll create a groom and we'll finesse the look we'll try to try and do all of that in the short time that we have this evening so the first thing i want to do is select my pig like this and we can go up here and choose create guides so i'm going to click on create guides and it will uh select them to the selection here and you'll see um we've got guides all over my pig there so i'm going to rename this guy these guys to um head hair because we might have hair in different areas and i want these specifically to be on the head the problem is it's all over the head we have a very hairy pig everywhere which we don't want we just want to localize it i want to give him kind of a mohican style i suppose so um to do that um what i'm going to do is um come down to where are we down to here we've got the density the density here is where we can control how much hair that we see at the moment it's 394. it's fairly arbitrary this number but if i put something like 900 you'll see i got three times as much hair so we want to pick a nice density for this to start with on the top of the head so we might go for something like 2000 so we have a you know nice nice spread of guides here so depending on the type of groove and style you'll do depends on the kind of density of the guides that you want and we'll discuss that a bit later on now the problem is it's everywhere i don't want it everywhere so um typically in houdini you could use groups to specify parts of geometry but what i'm actually going to do is use attributes so we can do that here on the goo on the groom node oh if we scroll down a bit you'll see that we have our density that we just adjusted but then we have over here overrides and here we can add overrides to control the density so you've got two ways to do that you can do it with textures that you've made in photoshop and you're bringing into your uv geometry or you can use it by using existing attributes on the geometry we don't have any but so we can create some so i'm going to choose that skin attributes when i do that it says look density attribute so it's looking for an attribute called density so we need to make one on our on our pig's head here and where the value is one we'll get a density of two thousand where the value is zero we'll get nothing and where we paint a value of point five we'll get a density of 1 000. so it basically multiplies by this density so we can affect paint by painting exactly how much hair and where we want the hair so i'm going to use it in a very basic way just to describe where the hair is going to go and a tiny bit of fall off now again this will automatically make the nodes for you traditionally we'd make an attribute paint node for houdini and do all of that but if you come over to the right hand side here you'll see this little magic button if you click on that this will create all the nodes that we need to paint that attribute and you'll see it's taken us inside the pig's head geometry and it's created um a density attribute here with this attribute create node and then a paint and attribute paint node where if you look at attributes we're painting into that density channel and we can see it here in red which means it's everywhere and you can see because we have the ghosting on here if i turn it off and turn it back on we can see what's happening at the level above and therefore our guides so we can see if the guides are working or not um sometimes it's slow to update so i'm just going to tap the y key which actually usually toggles on and off this button here why is that not toggling it on and off maybe because i'm in a brush let me try that again so yeah the y key toggles on and off this this ghosting view so select the paint density node and then over this 3d view you can hit enter which brings you back to the tool so what i'm going to do is actually set the value to zero at the moment it's set to one and my mode is set to um over sorry volume what i'm going to do is change this to fill which fills everything with the same value and in houdini's brushes you'll see we've got foreground and background float and i cut background number and the background zero and i can use the background here by using the ctrl key when i brush so if i hold down ctrl and left click i fill the whole thing with a zero value and you'll see the groom has disappeared i need to change the mode again and we'll paint with a volume this time actually we'll paint with the surface because it's more reliable and you'll see we've got a little surface brush now if i click i'm going to paint the value of one and as i do that you'll see the hairs appear where i've painted so we'll give them a little bit of a mohawk strip and then maybe we'll have some mohican hair come down to the chin there something like that excellent cool if we paint a little bit down here we'll get some down there but i'm not going to do that yet we'll do that a bit later on another thing we can do is we can soften the edge here you'll notice um the density where it's red we're getting the full 2000 density but as we fade off the colors here because this was a soft edge brush you'll see the hairs get less and less dense and sometimes you get a few rogue ones at the edge here again you can shrink the brush down and with control paint your background color you've got to hit the vertex because you're painting actually on the points there we go and that will remove and you'll see those hairs have disappeared and the same over this side a little bit so we can finesse it a little bit something like that just make that come down a bit more maybe there and another thing we can do is actually soften this and blur if we want let's make that a little bit more even so if you want to soften this we can make the brush big and then um what we can do is if you look here it says if you hit shift you can smooth the values so i make that big enough hold down shift and click you'll see it just blurs everything and that means the density just falls off a bit nicer towards the edge here i'm going to hit escape to come out that tool so i could see where the hair is and it goes down over the top so we can paint those regions as we need to i'm going to come out that network now we can see where that hair is the other thing we can do with the guide grooms is we can actually set the length of them down here so let me increase this length a little bit uh in fact i'm not going to do it then i'll do it somewhere else in a minute now um once we've done that we can come in here and start to finish things so i said i wanted to edit the length but i don't want to do it up here because i can get more control from inside and to do that we can use one of these other things here so the first thing you do when you do a groom is work out where you want it and where you don't want it the next thing ideally you want to do is set the length of the hair so it's all the right kind of lengths that you want and after you set the lengths for the hair you then start to style it and move it around so that's what i'm going to do next let me cut my video feed because my uh machine's going a bit chunky it's going a bit slow there we go so i do apologize you'll just have to hear my voice for a minute so um let's do that and for that we can go to these guide processes these are nodes that can affect the guides themselves and there's lots of stuff that we can do here things like setting the length set in the direction um and other stuff like that but the best thing to do to start off with really is to start off with the length so let's click on here set guide length and that will apply itself to the node we've got selected and what you'll see here is actually dive we've dived inside that groom node and we've added this node called a guide process node in fact there are all these nodes up here all these options up here at the same node you actually change the method here if you want to so you can add that manually and you'll notice it outputs three things outputs the guides which is what we see a skin which is the geometry and a volume to represent the skin that's our hairs will actually collide with the pig's surface so when we're grooming things won't go inside the piggy and again you can see because i've got the ghosting on we can see the pig there if i turn the ghosting off then that's just the groom that we've got which is not so intuitive so sometimes it's better to leave this on so let's select the guide process here and let's adjust the length so i can adjust it here by playing with the slider so you can make that bigger or smaller as we like so i'm going to make that um a little bit bigger something like this and again we can perturb the length with um an attribute if we wanted to so again we can bring down here click on skin attributes and again it's looking for an attribute called length we could actually use that density attribute that we made so let me type in density and now the length also affected by the density and you'll see where the hair's less thin or more thin rather it's shorter so we get this nice fall off where it's getting thinner and shorter and then building up in there we could actually create oh we could change the name here and then click this magic button and then paint in on top of that our own attribute but um i quite like doing it this way because then you get this nice kind of look where they they match each other really but it's entirely up to you how you want to want to to manage that and again this map multiplies by this length value so you can still change the length afterwards this just multiplies with that so you still get the same kind of fall off just a taller hair if you want so you can give them that kind of mohican style there most important thing is obviously to save because um houdini likes to well all software likes to crash so just in case especially when you're doing something processor intensive like this now that we've set the length um what we want to do is start to build some direction in this to start our sculpt off and there's a few ways you can do it one of the methods i like to use is to use this initialize guides this doesn't really initialize it basically just gives you another way to start off with an interesting direction so i'm just going to click initialize guides and it adds this in this this guide initialize node and what you can see it's flattened all the hair back along his head it looks like he's got gel or a slick back now the way this works is it's basically got a direction here and it's essentially like you're blowing a wind along the hair at this angle if i grab the red line here i can actually pull that angle up and you'll see how it kind of blows the hair around so we could blow it forwards like this and give a funky look or totally back the important thing is it gives us a nice quick sort of style to work with there excellent let me save so the next thing i want to do is start to build in a bit more um movement into this hair should we make that a little bit longer so let me just make this a little bit longer this is the wonder thing wonderful thing about procedural software is you can always go back in time and change stuff and look you could even click on randomize so we get random length values between these values so we could just have it slightly slightly irregular if you want let me just turn it off for a minute it looks too untidy that looks much neater but again that's up to you if you want to do that so the next thing i'm going to do is use this tool here curve advect what this does will do will allow us to actually draw directions we want the fur to go in so let me click curve add vect this time and you'll see it adds a bunch of notes which we don't really need to worry about all we need to worry about is sort of the radius of the tool this is how many hairs are going to be affected we're basically going to draw curves on that surface so if i just click down the left hand side here and off to the right you'll see how it pulls the hair off with if i go off to the other side i can widen it off that way too so on the top here as well you can kind of pull it up pull it around if you want create a curve that way or create another curve this way to give it a kind of a parting on the top and it's really handy is let's put another little advent there maybe does that one work very well let me make that a bit smaller maybe make this one over here maybe i need that one bigger actually something like that might work just to pull it out at the top there so we've got it really long and look at those hairs they've gone a bit crazy those guides oh no those are my curves actually i thought they were the guys there for a minute so we can use the curve advect so just to recap i painted the density where i wanted it i created a curved length to adjust the length and perturb that then we did an initialize to push it back and then a curve advect which allows us to draw the multiple directions that we want the fur to go in and as you saw it's very very quick to get a really nice starting point um there's other ways that we can move this around so let me demonstrate some of these other brushes to show you that so if we click on brushes these brushes will allow us to pull and paint these guides around in other ways to again extend or control more how you want the groom to go so a good one to use is the screen brush so if i click on screen brush again it's a little 3d brush here and this one is a lot more localized if i just pull in here you'll see i can just literally pull out little bits of the fur this time and get a much finer control so you'll notice i'm doing the big shape first and then going in there and then adding in the smaller bits later so i can kind of pull these hairs around the ear like this just tease those around the ear and you'll see because of this skin vdb the volume it's colliding properly with the mesh so it knows that it should go around the ear there and not through the geometry so again we can do that around here just part these hairs that way maybe make the brush smaller so just pull that one a bit bigger so i actually grab it there we go and then we can separate these over here and again it's about getting used to the tools and knowing which ones are going to help you do stuff maybe pull that up a bit give it a bit more life that kind of thing and um if we want to lift it up and give it a bit more life because now all those brushes have kind of flattened it down a bit we can use another node called the lift so this is the lift hair here so the lift will basically just raise them up against the surface so let's click on lift um actually i don't want to groom one i want to process one i don't want to i don't want to paint the lift i want to go to the process and do it more procedurally so with the brushes you kind of paint it in a granular way with the processes you kind of do it globally more so i'm going to click on lift guides and there you go it's lifted them we'll raise them all up and look we can there's a couple of things we can do here we can actually fade with blend and you've got blend with most of these nodes is you can actually fade the effect in and off on and off so if i turn it off that's our original but i can slowly bring it back in just to raise up some of those hairs there if you drop the contour here this means it's going to follow the volume but you can turn that off so it just lifts up randomly or you can sort of randomize that lift to create a bit more life to it but there's a better way to sort of create more variation to this a bit later on now what's interesting about the lift if i just pop the lift up high again what we can do is we can actually if you notice most of these processes if i look at this one as well you'll see there's a masking tab we'll use this for the lift the masking tap is really really handy what what this does it allows you to use create this lifting effect or whichever effect you want but to do it down the length of the hair you'll notice the hairs are slightly darker at the base and lighter at the tip and that's the mask that we're going to use so we can have our effect um fade in towards the tip or fade off towards the tip it's up to us so to do that we can turn on use curve mask and it's going to use the curve as a mask and you see the base is still tight to the skull but then as we come further away towards the length it starts to rise upwards and it's based on this ramp here this is the base where there's no lift and this is the end where there's a lot of lift we could reverse that for example so we could have a lot of lift at the base and very little lift at the end so it kind of lifts it up a little bit more and then pulls the style back down again so it gives us that little bit more granular control over how that goes and again we can blend that in or blend that off accordingly this kind of thing and then we could add another curved vect or another brush and then keep refining it as much as we'd like to which i'm not going to i'm going to leave it at that for the minute now what i'd like to do is add a little bit start to add a bit of life to this in fact let me just do um let's go back to another brush and give them a bit more of a look at the front here so i'm going to go to the um or is it the screen brush let's go to the side view here make that a bit bigger and i'm just going to pull the front of this forward to give him that bit of the quiff that we see on the mohican there let me do a bit more around the side and we'll come that tapering off quite nicely as we go down let's bring down the strength actually that's already in now if you've gone wrong with your lift you can up here hit reset strokes and that will just reset what you've just done so let me just pull it up from the center here let's pull up these little bits there and there let's go to the side a bit more let's pull up this oh now we're missing the that bit there so let's pull those bits up as well it's got a bit more of a slick back going on oh i don't know why i did that we've kind of pushed up that nice slick back here there if you want to come back to any of these nodes you can just select it hit enter and then you get back to the interactive handle for that particular um brush let's just pull those down a little bit cool what i want to do is add a little bit of life to these hairs so there's another great uh node that we can use and that's the another one of these process nodes here so instead of using the shelf we could just add them in ourselves so here we could type tab and then do guide process that didn't do it tap start to type guide process there it is and look there's various ones here let's choose the frizz one if you you'll notice when you drop it in it automatically connects for you and then we can turn on frizz and you'll see frizz makes it frizzy it creates these zigzags let's zoom into this here down down the length and that's adjusted by this frequency now if you make it very high frequency if i put a large number in here you'll see at a certain point it stops showing you that because we don't have the resolution if i turn on the points you'll see there's not that many points in each hair here so because we don't have any many points i can't have very frizzy hair because it's only going to bend where the points are if that's the case you can actually come out back up to this guide groom here at this level and you can increase the segments let me turn on the points so the segment is how many points are in these curves let's put something like 16 in and that should give us more points along the curve let me go inside let's just check that's coming through oh yep that's a good point because we made a change up at the top level here this change has not propagated through this network so there's a good button that we can do to fix that if we go to the hair utility no it's not it's in where is it there you go guide brushes we can click this magic button here recast strokes because in some of these nodes here we painted strokes um you'll see that here in the draw curve we made some strokes these everything needs to be updated down the pipeline if you click this button here recast strokes it forces any changes upstream to propagate all the way down so i click on that there we go we now get all those extra segments now we've got those extra segments we can see those smaller curls in there and now it looks a lot more if we turn the points off a lot more scraggly so just to demonstrate that again if i bring the subdivisions down to say six and click recache we'll now see we don't have enough points to show that those high squiggles if i put something like 16 in hit recache up here and you'll see we get the squiggles going down the length there which might be a little a little bit much and again we can use masking on that let me go inside and back to the guide process node here so on the guide process node again we can use the masking and we can use a curve mask again so it happens down the length and you'll see at the base it's not not frizzy but as we get towards the tip it gets frizzier and frizzier and you can control this as you saw not just with the ramp but also with this minimum and maximum range so this is starting at zero which is the bottom of the curve i can actually say start that ramp at the halfway point of the curve so now you'll see there's no f well there's the halfway and then this ramp kicks in from the halfway point so from halfway the frizz fit fades in if i bring this right up high then we only get really frizz right at the top there so we can bring down the range of the frizz like this and again you can bring down the top so that now the frizz is happening all the way down to the bottom if i bring the top down and again you can go back to um yep you can fade that in and out with blend up here so again we could sort of fade in the kind of frizz that we want so i'm going to put a little bit of frizz towards the end maybe just very subtly something like that very small amount kind of okay with that for the minute so let's see how that actually looks as a proper hair itself and then i can come back and refine some of this so i'm going to come out of that network and um this should not be showing it gray that should be showing it properly there we go it just didn't refresh itself cool so let's add a groom in fact before i do that and then let's add a groom and then we'll talk about the issues you might get with it so what we want to do is go back to hair utilities here and then we'll click on this generate hair so i click generate here it says select the groom object you want i'm going to select the groom here and then hit enter and then it'll take a second to process and then this hair gen node then calculates the hair around the grooms around the guides rather and there we can see our funky looking hair it doesn't look great there's some oddness going on especially at the front here it's not fading in very nicely but there's some controls we can do about that there's some things we can do to fix that so we want to create some mater material for this so it's shaded so to do that i'm going to go to houdini's material palette and look here's a hair shader let me drag that over and if i select that we can see the settings here there's loads of settings for it we can change the color we'll come back to rendering hopefully in a moment so let me go back to the object level so here on the hair gen shader i need to connect it here to the material so let me click on there open this up and i can select my hair shader and apply it and now we should see that in color i'm going to do is i'm just going to break this connection which is fine and you'll notice here we can bring in a groom object up here i'm just going to drag in my groom object to connect it that way now the color actually works that's a slight feature of houdini maybe you'll call it a bug but if you have this connected for some reason the shading color doesn't go through so if you break the connection that's fine you can just plug in the um the guides that you want to generate the hair from so now we see it in the color of the shader if i go back to the shader here and select it and then go back to here i can obviously change the color so i have red hair or whichever color hair that we want but i'm going to leave it at the defaults that we started with revert to default there we go and you'll see it shades it from the base to the tip so the base is a dark color and the tip is a much lighter color you'll see that much clearer in the render but you can see it's darker here and it gets a bit lighter as you go to the top now the first thing we want to do is fix how these guides work to make it look a little nicer so if we look at the actual hair gen node itself says it's using guides here so we're using the guides that are plugged in up there and we've got our own density control as well so we can control how many these little hairs will generate and these are the ones that are quite slow and you'll see they're picking up the frizz and the style from the guides that we asked for and you can see where i had the less density and the less length as well so the way it works is you take a guide let's have a look at this little guide here and around the guide we have a region of which it's going to scatter the hair and that region is this influence radius if i bring that down you can see we can actually get quite tight to the guide there but then it can make the hair look a bit more patchy especially these outer bit outer edges but the rest of it looks quite good there so it's about finding the right size for this and then getting the right density now when you've got problem areas like this if we don't want hairs here and here what you can do is actually go back into the guide click select the select tool here and then right click on this bit and make sure you're on primitives in fact let me turn off the uh would it would that help without the ghosting yeah maybe and then what you can do is select with shift um the guides that you want to get rid of so i'm going to select these ones and those little ones there because they were causing some oddness and i think we've got those ones selected it's a bit hard sometimes with the colors let's select that one as well and then once you've got the ones you want to remove maybe this one too you can simply hit delete on your keyboard hello houdini adds a blast node which removes those primitives so when we go up now they're missing we've got rid of them sometimes the painting's a bit fiddly look i want to get rid of that one as well so again let's go inside here select these maybe that little one under there was shift i'm not going to spend too long you could spend ages doing this i'm not going to spend too long so hopefully you get the idea so we can come in there and we can start to finesse and remove any awkward guides that are ruining or making our groom look a bit odd there's some down the back here but um there you go that'll do let's hit delete we got rid of those might want to get rid of these ones here as well so let's hit delete again and let's have a look at how that groom looks there we go so we've tidied up those weird little rogy looking ones i think the rest of that looks pretty okay so we can easily go in after the event and just delete guides that are unnecessary we don't need maybe get rid of that front one there and that one too and again if you decided you want to keep it you can simply just disable the node and they'll come back again it's one of the nice things about houdini's proceduralism the fact that it's very very flexible so we come back up that's looking a little bit nicer at the front there we've got him his nice little mohican very good so um there's another little effect let me just hide the guides the display the guys so we can just see purely the groom there which looks kind of funky let's go around the ears as we want so there's another thing that we really like to add let me increase the density actually let me put the density up to maybe fifteen thousand maybe uh twenty-five thousand so he's got a nice thick head of hair unlike me there we go doesn't look that great but um looks like a bad wig actually but anyway need to spend a lot more time on it what we can see is that the guides are affecting um the hair here we're seeing a little bit of what's called clumping hair naturally clumps it clings together with a bit of static it also clings together because of a bit of natural grease in there and you see this sort of clumping it's not very uniform and we can create that um quite easily and get a very nice natural effect from it so to do that i'm going to actually do it on the groom we can create clumping on the guides or actually on the hair itself i'm going to do it on the hair here excuse me so i'm going to go inside and since we're in here we want to look at hair tools so i'm going to type hair and i'm going to use the hair clump so if i just put that in you can see what it does it gives us an error because we need to plug in the skin here as well and also um we should plug in our volume skin vdb into that last slot here so skin vdb now that we've plugged those in you can see what the clumping does it clumps the hair together a bit more around those particular guides and this will give us that sort of you know greasy or matted natural look so here we can play with the clump size we can reduce it down make it much smaller so it looks more natural and uh we can also increase the crossover rate what that means is some hairs in one clump will suddenly jump over to a neighbouring clump which just breaks up the uniformity of it and to break up the uniformity even further make it look even more natural we can click on fractal clumping as soon as we start playing with the iterations you want a reasonable number you'll see it just starts to break up that rig that irregularity in it you can tweak some of these settings to sort of make it seem you know more or nice more natural or less natural depending on your reference and again we can use attributes to paint this so we can have different clumping based on either texture maps or painting as we go so that should look hopefully a bit more natural especially down the back here where you can see hair clinging together in certain ways and that was that was the effect that we're after so clumping clumping is really good for that so what time have we got we've got uh probably about another five or ten minutes time does fly when you're having fun so what we'll do is we'll move on to the rendering but i'll just recap the technique again so you apply your groom you then paint where you want it to be the density then the best thing to do is adjust the length once you've adjust the length you can start to pull it around into shape once you've pulled it into shape you can add the smaller details of the brush like just pushing out extra bits that you want and then the last bit is just to add the clumping on top just generally because you don't want to mess with any of that and you can go back at any time and bring in your brush tool again and re-edit the guides which will change the groom if you want to that kind of thing just really is quite a quick start so let's have a little quick chat about how we might render this let me just save it again so you'll see it's very easy to um do stuff in fact there's some other really cool tools um that you can use but um yeah let's get on with the rendering you can cut it and do all sorts of wonderful things where's the cut gone is it there so yeah look we can cut hair this is an interesting brush so i'll just demonstrate this one so if you want wrong thing so if you want to cut the hair you can choose the cut hair brush and literally if you just click it cuts um it cuts it where you've clicked so you can get really nice edges like that let me just undo that twice so if i bring that down something like this we'll see we can cut the shape of the brush in there so generally this is quite good for getting those straight edges right across like this like broom handles all that kind of thing so i don't really want to cut anything i just wanted to demonstrate it really because i quite like that one and again we could extend the hair we could smooth out bits of the frizz with this we can add a parting in there as well this will part the hair for us so you know you should check out a lot of these tools just to see how you might get in there but the first thing you really want to do is set the length set the direction with initialize wherever that's gone initialize and curve advect and then you can start to do this more finer stuff like cutting and frizzing and depends how much you want to work into that groom so yeah let's talk about the rendering let me save so very quickly i'm just going to find a nice angle something like this control click my camera to drop the camera in just reposition that and then i'm going to create a a light source for him so let's come up where's the camera it was there let's create a uh a three-quarter light up here so spotlight just drop one in there let's drive that over here and then i might create a second spotlight around here to fill in these shadows this is called a fill light so drop a spotlight in there you'll see that one's a bit bright so i'm just going to reduce the exposure of the fill so i've got control of the contrast let me go let me look through the other spotlight because i might just want to come around let me look through that other spotlight just want to come around a little bit so we've got a bit more lighting around the front and if we look through the camera you can see our little piggy there let's come a bit more three-quarter so let's get a bit closer to the hair so we can actually see it and uh the nice thing about lighting hair generally is lighting it from the back or creating a rim light as we call it so i'm going to do that i'm going to look where the camera is like this i'm going to create another spotlight let's bring that up like this make it a bit closer and a bit smaller let's bring the brightness down a bit and uh we'll play with that backlight in a moment when we render let's go back through the camera if you turn on this bottom display you can see sort of the lights there and i can bring down sort of my main key light if i want i can play with all the balances in fact i'm going to disable the key light and the fill light and i can see totally what the rim light's doing it's not doing what i want let me lift its interest up a bit there we go so it's coming down more on the top of the ears here and the top of the pig cool so let's do a render and see how that looks let me turn the other lights back on otherwise you won't see anything so to rendering houdini we've got to create a mantra node so we'll go render create render node mantra and i'm just going to make the res smaller so it works quicker and if we go to the render view let's just make these windows big we can hit render and have a first look at how our hair looks and again we've you know um we've got to understand how hairs work you know coarse hairs like horses hairs or you know things on a brush they'll be quite thick and quite um non-transparent whereas things like cat's fur is very very dense very thin and quite translucent so fluffy furs have lots and lots of hairs that are very fine whereas coarse hair has not so many hairs but they're much thicker and we can adjust all that in shading now this gives us an error because by default it doesn't render which is wonderful what you need to do is click the actual groom here go to render and say use the actual geometry so we'll use the curves in the scene so let me hit render again and now i'll be able to generate the fur curves for me so you must remember to turn this on otherwise you won't see your groom so give it a second now to calculate all those hairs and we can change various stuff here in this hair generate for example we can change the thickness of the hair on how it appears in the render we can adjust the density as we saw before and we can affect also we saw the radius already so there we go there's my pig being lit let me just bring down the brightness of the front light so you can see it being backlit a bit better there we go see the rim light kicking in there making the hair glow at the top which is quite nice let's get a little bit closer i'm just going to hold down shift and left click and drag to make a render region that means this bit will render a little quicker i mean kind of see how the hair is looking and you see it's quite shiny so again we can come here and we can go to thickness and we can make it a lot less thin so let's do point one so it's half as thick so it looks much finer and not so coarse and again because it's much thinner the hairs it looks like we can see through them more the thinner the hair the more density you need to make up for it so i'll go back to density here and then maybe double the density let's go to four instead of two because i don't want to see the ear through the hair there so it'll take longer while it generates that more hair more density and there we go we're filling in the gaps with our finer hair again so i will just want to tweak the shader a little bit i can click this little arrow here and that will take me to the shader and it didn't that time there we go sorry is this one here matte hair so let me click this arrow that will take me to the shader and here we could adjust the color if we wanted so it's going from this sort of like dark brown to light brown but it's got a lot of sheen on it here with this sort of reflection if we turn off the secondary reflection you'll see we don't get that sheen but hair naturally has that so we'll turn it back on what we can do is just reduce the intensity let's bring that down a little bit so it's not so pronounced but it's still there a little bit so he's got a bit of gloss in his hair so if hair is shiny it means it's very smooth your actual hair fibers are made of scales and depending on the roughness of those scales depends on your hair type people with really silky hair have very smooth scales people with rough looking hair have very um rough scales so when you've got unkempt hairs because you've probably got rough hair and you can tell by when you wash it whether it comes out shiny or not really and everybody's different but that's the kind of controls that we've got with this sort of intensity suggesting the roughness of the hair if we go back to uh primary reflections again we can also bring down the reflections generally overall on the hair but the secondary one's the nicest one i think we can also add a bit of a reflection shift which just adds a little bit of color difference but which which we might not notice here and we can go to randomness as well and add some randomness to the cut to the um hairs so for example we can change the hue so um the hue is sort of the color so it can go from browns or reds or whatever so we've got a very small difference in hue here if i put a big difference in hue we'll start to see um hopefully some rainbow colors in there let's make that even bigger let's make that one on one there we go we're seeing much more variation in the hue of the color so we're seeing purples and blues and everything which is kind of interesting but not what i want what i want is just a very subtle difference between the browns something like that 0.05 there we go so there's a small variation between the browns we can also add some randomness to the saturation of the hair so you can desaturate it so in parts and you can also add some randomness to the diffuse brightness and also the reflections that's the specular intensity is also known as the reflections so you can do some very very nice stuff with it um what the good controls are there now the root to tip blend this is how the colors fade off along the length and you'll notice we've got used white hairs turned on if i turn that off then they'll all be dark so they use white hairs just create some random natural white hairs within there um oh actually we haven't got them on that says use white hairs what we need to do is actually create that if i click on this button here add white hairs it'll add a few random white hairs in there so you can suggest there's a bit of age in the character so you know rather than or just will jet back they're going a bit grey in certain areas now in order to see that better we really should um increase the resin so let's go two thirds resolution we'll get a little closer in fact let's go full resolution so we can just see what's happening up here it'll obviously take a bit longer but we can see those finer hairs in much more detail now cool so that's kind of shading nicely one last little trick i want to show you is um we can actually add some dynamics to this if the pig moves all that hair will move with him and but also if i have dynamics it will just make it naturally full with gravity as well which will just make it seem that bit more natural and it's very easy to do that what i'm going to do is i'm going to select the guides here let me turn that off and turn the guides on because we add gravity to the guides here so up here i can go back to the hair utilities and um i can choose simulate guides so that'll apply to the guys that i've selected and it uses houdini's vellum software which is great for animating curves or cloth or all those wonderful things and there we go we can see um our guides now have become blue as we're now going to simulate them so if i press play on the timeline you'll see they all sync with gravity and they bounce off the head they collide with the head there looks a little bit flat a little bit too greasy the thing is it naturally now hangs around the ear and down the back of the head there but not quite matching my groom so there's a few things we can do we can add some stiffness to this now the default settings for this are kind of interesting they're for speed not necessarily accuracy so in order to really see vellum working properly we need to increase the sub steps and that's here in the vellum solver tab you need to put let's put say three sub steps in it does slow it down but if you look it doesn't really have much of an effect because we need to put some stiffness in let me put that back to one to show you how it works to put some stiffness on this and we go to vellum constraints and the hairs themselves have either a stretch stiffness which stops some stretching and they have a bend stiffness which stops them bending let's increase the bend stiffness i'm going to put in 10 000 generally you need quite high numbers if i press play it doesn't seem to have an effect or just subtly whereas if i increase the substeps now to three see it has more of an effect it doesn't flatten so much if i put the sub steps to five it's able to work out those collisions more and look it it's slightly more stiff it doesn't fall so flat i'm gonna make it even less bendy let's add another two zeros still going quite flat let's add another couple of zeros you know that's sagging down a little bit nicer that kind of thing once you're happy with that what you can do is turn on freeze frame uh unfortunately now that's going to run up to frame 50 to be my freeze frame there we go on frame 42 44 50. so now it's locked at frame 50 from the gravity now i can move the slider and it's not going to change anything now i can actually turn on my fur and see the result of that after the same let me hide those guides so there is flattened down as if with gravity as well so you might want to create effects like that obviously if you this is animating you don't want to turn on the freeze frame so that this will pick up the animation as he swings his head around and all the hair will move appropriately so if we go to the render view now let me save this image by making a snapshot and we can render again and see what it looks like after gravity has been applied and again it's up to us if we keep that we can turn it off we'll do another version or mix it in that kind of thing cool so um that's pretty much it for the introduction to the groom it's quite a lot to cover in a short time in just under an hour on these webinars and as you can see there's quite a lot of tools but they're really easy to use you literally can just click on the shelf tools and play with them and it's fairly interactive and artist friendly uh as long as you've got a good methodology and like i said the methodology is paint the density where you want set the length um push it back with a big form like with the advect and then go in with the brushes and put in the small details later much easier to work that way and at the very end clump it up to give it that naturalness so if you do those kind of steps you'll find yourself being able to get to grooms a lot faster than just messing around otherwise so there's before gravity after gravity and the other little trick is hair always looks wonderful when it's lit from behind it just looks so much more interesting so if you look in all movies they tend to rim like or backlight people for that reason just makes it look much nicer so if i just hit shift and left click away i'll be able to render the entire piggy there you

Channel: Escape Studios

Views: 2,549

Rating: 5 out of 5

Keywords: Escape Studios, Escape, studios, VFX, Visual Effects, CGI, Maya, Autodesk, Nuke, Foundry, I want to learn, tutorial, modelling, rendering, dynamics, texturing, animation, renderman, compositing, ncloth, motion graphics, design

Id: yAqVUe9RZso

Length: 55min 8sec (3308 seconds)

Published: Tue Apr 20 2021