How to use the Position Pass in Nuke

the techniques present in this video are only a suggestion they're not the only way of making something in Nuuk compositing in a node-based software is very flexible so there are always several ways of making the same result if you don't like my techniques and you think they are incorrect well they're not they're just another way of doing the same thing well everyone my name is zu geta from Yugos desk now this is episode two to my brand new video series called you just have to be better yes better you know when you're not that good but you just should be better so every week I will present a tutorial for visual effects in around 5 minutes around 5 minutes you say well I am quite tired of very long tutorials and it's not like you can't watch the video again you could watch the video again if you want let's get on with it shall we episode 2 you just have to be better at using a position pass in Nuuk timer starts now here we have the files that we're gonna use today this is the final render is a shot from the Just Cause 3 game cinematic I did last year it's shot 40 which is a car flying through a lot of fire now fundamentally for this shot I am going to show you how to use the position pass to basically you know lie your some fire elements and certain things we're not gonna put the fire elements in this shot on this tutorial because it's only a 5 minute tutorial but we are going to show you how to set up correctly the position pass for the position pass you do not not mandatory but you should have a normal pass that should be one of the things you should have you definitely need a position pass now if you don't know what a position pass is then let me just go ahead and Google that for you ok so now that you know what a position pass is let's just get on with it again one thing that is important for you to know is that for this to work you need a camera and the camera needs to be a correct camera for the shot that you're working on and also the position pass in the normals pass should be 32 bit float now from that moment on you just have to open up the position two points no now the position two points node has as you can see one input it only has one input to tell you pipe something into it the first thing you need to pipe into that first input is the beauty or the render and then as soon as you put one input on you'll see that the second input will show up the second one is called pose which is four position Pass and then the third one will show up which is for normal space and then you hook at that in to the normals soon as you do that you'll see that the position two points node will now generate a point cloud in the treaty system now this point cloud will be an accurate representation of where the elements in CG are so this means that this point cloud will actually be to scale and it will match exactly the scene done on it through the application in this case this was done in Maya so you have a one-to-one representation of where the geometry is now the into this node not only its for doing real lighting which we will talk about that next week but the main aspect of this is to you know put to the elements like fire elements and smoke elements in any kind of 2d elements you want to add into your shot it's also also good for you to put a scanline renderer and a scene in the camera now as soon as you hook up the camera to the scanline into the scene you'll see that now the camera lines up and that's what the position passes the position pass is nothing more than a projection and so when you look at it through the cameras angle it looks exactly like the beauty now one of the things you will realize is that although you can see it on the beauty you can see that it's it's a point position which means it's a projection on point so the quality of course the position pass is not meant to be used in 2d so in this case you could change the point detail and the point size and if you do tweak that you can get a better definition in your position pass there it's not very important because not only not a lot of times you are actually gonna use the position pass as an RGB element now one thing I would like to let you know about the position pass is that you know although you do need it in the treaty system you do not need it in the 2d system so you should be aware that most of the times you do want to switch off the 2d rendering of the position pass because it's extremely slow now in the position pass as you can see you have the display which is what you can see in the treaty system and that you should leave on so did you see it but then the render is what comes out of the scanline and so you should turn off the render to off so that it doesn't show up on the scanline renderer and then this time it will be much faster on your composite so one of the most common applications of this technique using the position passes to for example on this shot which was a project I did last year for rival kingdoms I use this position pass technique to actually put the fires into the scene if you wanna see a bit more about this you can always go and watch the video for this constructing the rival kingdoms project on my youtube channel the link is just on the screen right now and so as you can see here I do exactly the same technique using the normals in the position pass and using the points to point to position and and then using 2d elements of smoke for elements you know particle elements and dust elements as 3d cards and then using the position pass to know where to layer them and to have them in the correct paralyze so as you can see here when you look at the representation of the scene then by knowing where the columns are you can now easily put the fires on the correct places of course in the next tutorials I'm actually going to show you how to use exactly the same node to do some real lighting so that you can actually effectively affect the CG with the elements that you're placing into the scene and time is up so next week yet another you just have to be better at something please subscribe like share and leave me a comment if you did not like this video well you can just leave you know there's just just leave thank you so much for watching

Channel: Hugo's Desk

Views: 30,040

Rating: 4.9326601 out of 5

Keywords: Nuke, The Foundry, Tutorial, Nuke Studio, Position Pass, Compositing, Visual Effects, Training, VFX, MPC, The Mill, Hugo Guerra, HugoCGuerra, Hugo's Desk, XYZ, Re-Light, CG, CGI, 3D, Nexus, Fire Without Smoke, ILM, Dneg, VES, FXPHD, Escape Studios, CMIVFX, FX, Hugo

Id: n4YyanHkHEs

Length: 6min 32sec (392 seconds)

Published: Sun Mar 06 2016