TUTORIAL: Advanced Corona Scatter

everyone welcome to another corner tutorial today we're going to take a look at corner scatter and specifically how to use it to create some scattering distributions with some advanced effects such as using curves open or closed curves to exclude certain areas from the distributions as well as using meshes to exclude some areas or include some areas and distribution I will also show you how to adjust the distributions of the instances based on the slope of the surface we can also try to adjust the distribution using some advanced procedural textures and basically I'm sure many of you are familiar with forest pack which is one of the most popular scattering plugins for 3ds max and I'm sure many of you know that it offers some of these advanced distribution options and I'm definitely not saying the corner scatter is not gonna improve in this way as well in a way that those options will be more accessible right in the user interface of kernel Katcher that you won't need to do any manual kind of map buyer map wiring to get these effects but if you are using kernel 1.5 and you need to create some of these advanced distributions right now at this point then there are some tricks not many of not many people know about with which you can achieve achieve those results right now with this kernel version so let's get right into it and let's overview our scene which we are going to be working with so there's ground simple kind of charring ground then we have little house and this house will serve kind of as a example of the area where we do not want any foliage to go in then there's our foliage the two trees and a few clumps there's some wheat which is like the tall tall grass then there's regular cross some death that dried grass and some dandelions and this is pretty much all we are starting with so obviously one of the first step will be to create cross scatter and let's call it Schuyler grass so there are some organization in our scene now distribute an object distribute on the ground and tour do we want to distribute it's all grass now you can see all across appear it won't be probably as automatic as this with your scene because I've already set up the scary ones and it's dug the settings in there from the previous scatter so the difference is I'm displaying only 0.05 percent of all the instances in the viewport so it remains fast scale is randomized from 100 to 300 percent there's random rotations from minus 180 to 180 degrees and I'm scattering 400 thousands instances now we had some weed in the in a mix and we can see it here and I don't want the wheat or the tall grass to be as as frequent as the rest of the grass so I'm gonna decrease the frequency of both wheat meshes to 0.1 so they have only 10% of the of the probability of appearing okay so if you look closely this is kind of the simple class distribution and the first thing we probably want to do is we go to view and look here we can see there's this nice little path going across our terrain and obviously since people walk there the crowds will be mostly stumped so there won't grow much of it and therefore we don't want we do not want any grass to to be scattered in there so let's make this transparent disable the wireframe and create a spline across our path so just a few clicks megamouth smooth and do just a little bit of tweaking so we get the spline right on top of our path like this okay so now once this is ready I'm gonna quickly go here and grab our ground material to do order order slate editor view so we have it our disposal and I'm gonna show you something there's new distance map in Khurana 1.5 basically the map that which creates fall-off based on the distance from the object the object apology and it can be used with the splines as well so I'm gonna assign this material to the background and this distance map as a diffuse and you would immediately think how so I can use this distance map to select this spline and drive distribution of this child distribution of the grass with this spline the issue is it's not it's not it doesn't do the projection of the spline in the z axis it works in the three dimensions so if I create at the spine here make sure the color far let's make all of our dark rail let's make collinear completely white and what you can see is as I move the spline would increase the distance to let's say two years obviously in some places like here the spline is really close to the topology but on the places like here it's more distance so it it doesn't do the Z projection it does it in the three dimensions so in order to use this spline as a mask we first need to extrude it and push it down and voila there's our mask we obviously do not want this to be renewable and we do not want it to be too obstructive in a viewport as well so I quickly made it see-through now this is better and this weekend were they work with so let's go back to an isolated you let's assign terrain material back to our terrain and oh let's wait for the autosave real quick there we go so let's take our scatter our spline and our ground isolate again so we can focus only on these three and obviously where there's near color near of our spline we do not want any submission so that will be black and further from our spline we do want grass to distribute so whatever white okay let's call this mask get rid of this material we do not want it anymore and the first kind of idea you would probably get is okay so now I will use this map to mask density of the of the scatter the issue with this is that density is really bullying you cannot do gradual density adjustment there's only two states the instance is there or isn't there so in the black and white case it's easy what is the instance is there black is the instance isn't there the grayscale he'll here means the probability so in case of light gray there's high probability the instance will appear on that place if there's very dark gray there's well a very low probability that the instance would appear there if there's 50% gray then there's fifty fifty percent chance that instance would appear on that given place what's actually better in this case is to map the scale with this map which we are going to do now but maybe we will be putting more maps or trying different things in here so what I'm gonna do instead is add output and call it the same name as this oops there we go and plug this into our scale so with this little trick we can always stay in our material editor and we know this is the kind of like the shortcut the shortcut to this slot right here so even if we have selected some different object like this we do not always need to go back to viewport selected and drag them up all the way over here especially if you have slate material editor on the other monitor so this is kind of like the pipe that leads through the scatter so now let's plug them into pipe make sure our scatter update and you can immediately see that the path is there and you can also see that exactly like in the real world there's like large grass on the further away from the path but closer to the path they are smaller and smaller clumps of the grass whereas if we if we were to use the density mapping here you can see the way the probabilistic way it works wouldn't really work well in this case so again let's use this and let's clear this all right so this is kind of the easiest way you can exclude for example path from your instance distribution and I'm sure many of you know in the first back you have some kind of advanced control over this a distribution so for example you can tweak the fall-off curve of the of the scale scale distribution so I can do the same actually in here I will just plug the output map in between and it will color map and I can for example make the size distribution so that the size fall falls off in kind of this shape from the from the edge of the of the path to do more distance area distant areas away from the from the path so if we know that this we can increase the distance even further this is bit extreme oh and make sure our scatter updates or we can go the other way and make it a really sharp transition obviously again decrease the distance and now you can see the fall-off from the big grass patches to the small one it's extremely small ones it's extremely sharp and quick I think in this case I preferred a more linear way so I will just get rid of this this output here I'm gonna make sure our schedule updates there we go so let's go back here set it back to two meters and there this is it for the for the first example the next example would be using the same thing but just with the closed curves so let's say let's create a circle oops didn't want to do that this circle and again we have 2x true it so let's do that put a circle down or its cylinder now make sure it's not renderable and also if we do not want to eat to obstruct our scene too much we can always display this box if you want to let's duplicate this and call it circle mask for example remove the line and let's add the circle and let's plug this one in and update our scatter and now we can see we've excluded the circle but obviously in this case you would most often want to exclude the the entire volume of the object so in this case just stick on core inside and make sure inside it's black as well and there we go now you can exclude the areas we can convert this to editable spline we can take the editable spline go to table view and move it around in any way we want like making this egg and if we go back then we've excluded this egg shape and again we can precisely control the fall-off so let's say it's 20 meters fall off and now you see there's no gradual scaling up from the edges of the of our egg shape and again you can plug your output map in between and precisely tweak the curve of the fall-off if you want to so let's sit back to 2 meters and now let's say you want to combine this distribution distribution solutions the easiest way would be to simply plug this let's say to turn fart X map and combine them this way but there's better way I'm gonna show you later on and I'm gonna also explain why is it better so first of all let's just finish some setup of our class so let's make something that actually looks good okay so we have the path excluded but let's say now that we do not want the class to be growing on the slopes because there are cliffs the cross doesn't go there so not many people know it but Colonel scatter actually supports full of map so we can grab the followed map and let's call it slope mask for the organization and we want to do perpendicular parallel so let's keep it this way but we want to do it in the world to y-axis and just plug this in here you can see not not much has changed yet but now if we go to the mix curve just to make sure our scatter updates first and wait for the autosave again there we go that looks more like it let's chest at two points and we can now use these to precisely clamp the distribution of the grass where we want it so this is gonna be how would a sharp transition is gonna be and if we select them both and move them then this is going to offset the distribution and we can see we are doing the exact opposite of what we want it we are scatterings scattering on the slopes only so what we all.we we have to do is just swap these two colors and we have exact thing what we want it we are now scattering everywhere except the slopes so let's maybe push it even further in there actually the other way around there we go yep this is this is something I'm happy with so this is another thing and next thing we want to do is to make sure that the grass doesn't grow right inside of our house so if we take a look at the house you can see it's now full of grass and we don't want to have that so let's just quickly create a box line it to our house and quickly model kind of the outline of our house now there's this little kind of like porch or wouldn't step which we want to exclude as well so just extra days out and call it house house bounding box something like that again make sure it doesn't render get another car distance label it house mask add it in again Cora near call it far that makes sense so let's go back to our entire scene and again take only the things we want to focus on with us and isolate again and once I plug this in we should see that the grass is not scattering inside of our house precisely like this you can see how it ends right next to the house we can increase the distance and now look grass stays away from our house so now that we have these three different masks we can combine them again as I said it wouldn't be a good idea to combine them and they're just plugging inside of each other because if we have multiple scatters and we have them plugged inside of each other then if we want to use some of the masks for there's some other scatter and have it linked so that if we do change to this distance texture it propagates across across all of the scatters if we have some other Maps plugged in then we can we cannot use it because we want to specifically use only this map so better way is to use mix where this one will drive mix amount and this one will go to the white spot of the mix and then again another mix again this one a result will try to mix amount this will go to the white spot or the mix and if I plug this in and make sure it updates now we have the distribution where our path except is excluded our slopes are excluded and the house is excluded as well so now if we were to scatter let's say trees so let's create a new corner scatter you know quickly call it scatter trees obviously we know we do not want to blow this up so let's say four hundred trees at most and fifty percent display scattering on the ground and what do we want to scatter it's trees that's a lot of trees so let's adjust the size randomization we do not want to align them to be aligned to normal let's decrease count to the two hundred that looks better that looks something like forest translation maybe randomizing Z from like - three years - two years - zero meters and now if we create a new output scatter trees in this case we better we don't want smaller trees on the edges so we will be mapping density instead but now we have this house mask so we can already put house masks in the density density map and if I if I just isolate this we can already see that we have used this these oops I forgot to grab the house we've used the same map or the same mask to drive multiple different scalars so we are now sure that none of the trees intersects our house and if we do some changes to the bounding box geometry of the house it will change the arc grasscutter as well as our three scatter so now let's play with the distribution of trees a little bit let's make the forest a little bit more dense so let's say 500 trees but let's make it in sort of small pools so create noise like this here give it a moment refresh maybe the noise is just not large enough so first of all we want to make sure its world and we want to clamp it so there's not much of a grayscale going on so let's use 0.5 0.4 t9 fractal so it's bit more irregular and make it really big so like 2000 and now we are getting somewhere now we have we have the small islands of the of the trees 3000 and we can sort of play around with the offsets to get them the way we want just some you know randomization analysis it's really close I think yeah let's say let's say we like this for example and now I I want to combine it with the house mask so again this will be mix amount and in the white slot we'll go to the house mask so now you should see that some trees may be here and disappear but probably none because the house was somewhere where the trees already aren't and now we have the trees probably on our path as well so what we can do here is duplicate the path mask we cannot keep it instance because the trees will need a bigger distance so let's say five meters and plug this here as a test I am going to take the scatter as well as the ground just wait for the auto safety finish okay and now if you remember I said that when there's greyscale there's just probability so we want to climb this so there's no greyscale going on there it's just fooling black or white so let's enable color map at two points this one is going to be 0 5 or rather zero and zero five here and the other one is gonna be 1 or 0 5 in this axis 1 in this axis okay now it's a real clamp and if we increase the distance to like 20 meters we now have all of the trees staying away from the path we can go to like 10 meters so they are a bit closer to the path and again once this is established less scholars of masks white we can again let's call this trees mask noise so we know what is what we can again combine them easily into one thing so now you can see we have the random distributions of the trees trees will always stay away from the house and trees will always stay away from the path okay this looks great and the last thing I'm going to show you is why we did this split of the with the mixed maps in the first place we're gonna take the ground and flower create a new kernel scatter all it scatter flowers new output scatter flowers and put this in to do density we do not need size fall off here either so again let's set this to something really tiny ramp up the count we're going to distribute on the ground and we are going to distribute our dandelion just give it a second oh and obviously we want different distributions from the trees so this really won't do that's better and in the case of these flowers we won't slide like the natural pools of the flowers you know do not want it to be like the even distribution so let's get cellular plug this in here and make sure its world give it a few moments to update and let's make it again really large and the division color in order to clamp our distribution again so there's not much of the gray there's more of a white and black or set the division 2nd division color to the black as well now we have nice kind of pools we can treat the spread to make them spread more or less so we want to spread them obviously less like this okay this is looking quite nice maybe not so dense so let's try 100,000 yeah let's keep it at this and now I for the for the dandelions I want to do the exact rules as for the grass they don't want to grow on the path they don't want to grow on the slopes aid and they don't want to grow in the house so all I need to do is take mix this network right here is the distribution rules for the grass so it will go to the mix amount and this is a distribution rule for the dandelions and these patches so that will go to the white color and that will go to the scatter of flowers and if we wait for it to update you can now see the rules have applied and the dandelions do not grow on the road but in the case of the grass we used size so let's you know what let's put it in the size just give it a second clear it from the distribution now we can see the size messed it up as as we we have a lot lot more of the gray color here so let's just bump up the spread and use the output map to clump our result let's see if this works yep it does it does exactly what I wanted to do so now we can see again we have those patches but I I did a bad decision here to put it in the density slot because I forgot that this network is set up for the scale slot okay so now the rules work exactly as we want them there's nothing going on the path there's nothing going in the place of a house and there's nothing your own on the slopes so if I now go back then we can kind of look at our entire environment maybe let's get a little bit more Sun in there there we go maybe is a blonde contrast as well and increased exposure okay so I think this is it for the for the advanced scattering tutorial I hope you found this useful and I'll see you next time goodbye

Channel: CoronaRenderer

Views: 93,954

Keywords: Corona, Corona Renderer, Corona 1.5, Corona Renderer 1.5, DistanceMap, Scatter, Corona Scatter, CScatter, Slope, 3ds Max, Scattering

Id: uXSy8ypPPUQ

Length: 39min 2sec (2342 seconds)

Published: Thu Nov 03 2016