Redshift 2 Maya - Tutorial #9 - Caustics

hey guys so this tutorials going to be covering caustic effects in redshift and how to basically get them working and so this is a pretty easy thing to set up and in redshift all you got to do just turn on a couple parameters and it's good to go and so for this scene I just have a basic glass shader so let's start up an IPR and so right now it's just a glass shader with a little bit of dispersion so you're getting some cool little chromatic aberration in there and also I have two metallic objects just this rod and a sphere and that's because caustics can also happen not only on refractive objects but it's the light bouncing off of certain things better you know like shiny materials and stuff showoff caustics pretty well so like this these are kind of chroma SH colors and then obviously refractive objects which is the one everybody knows about and so a lot of rendering engines don't use real caustics they use kind of a pseudo softened caustic system they don't do hard caustics like Arnold doesn't actually do hard caustics and the reason is because it basically takes forever it takes forever to do hard caustics in most render engines especially the brute force raytrace caustics method and so redshift uses a point cloud method which speeds things up dramatically for caustics and so yeah i'll basically be showing you how to turn that on and so one thing to note about caustics is during the IPR phase they do not work you can't see them because IPR is all ray traced progressive rendering it doesn't actually use any of the point cloud methods for making the caustics so to actually see the caustics in effect you have to do final renders or bucket mode and that's just one of the limitations so basically all you have to do is let's just pause this is first step is what objects do you want the caustics to be to be hit basically so let's move that out of the way so if you have your your objects so we got these two objects and you go under the the mesh parameters under redshift you go to the bottom under visibility normally this is checked off so you check that on and then right here you have an option it says cash GI photons or cast caustic photons you want to check this off this is off normally when you first turn this on and so if you want this the object that you have selected to actually cast caustics check that off so on this object will already turned it on on all these other objects and so these objects are going to cast photons caustic photons and so now that the objects are able to cast them what we need to do is make sure that our lights can do it so let's open the light editor and we'll just check right now this scene has two area lights and one dome light the dome light you could do it with HDR you can turn on caustic photons but either usually HDR as they kind of fire them all over the place it's slower it's generally not a good idea to cast caustic photons from an HDR that's still dive just found that that's a problematic thing and it's slower you're better off not turning it on for HDR dome lights so I'm going to leave that off but for the area lights that are interesting we have two of them once you click on your light you go all the way to the bottom there's this photon tab right here so you check that off and there's the caustic section don't worry about GIS if you're going to use GI photon mapping and that's just an old deprecated system that really you know nobody really uses anymore use brute force or irradiance cache stuff like that so the important thing for caustics those here you want to admit caustic photons and so there's two sliders the intensity multiplier you want this at one basically means on and the higher you increase this it basically multiplies the brightness so you can let's say your scenes a little bright and you can barely see or caustics you can bump this up and brighten the caustic so they stand out so this is useful if you know if you want a little more bang inside the caustics so they're bright and you have number of photons admit so this is basically the amount of photons that are being fired from your light and the quality so if you have a lower number it'll render faster and at the same time though it will be a little noisier and stuff I generally find that this is a good amount five million but let's drop it down to two for now and so let's turn it on on our second light drop that down to two just so we can do a comparison of before and after and I'll do a comparison of the multiplied and okay so now we've turned it on on our objects that we want emitting caustics and our two lights so the only thing left to do is now you go to the Settings window and so when you first open up your redshift settings you're going to go all the way to this photon tab and in the photon tab you just check off enable caustics for these settings I just leave it all at default the only setting that really a change is the search radius and the caustic photon number of the max so normally to just for testing purposes you could put this down to like one or two and it's going to be noisier but since we're going to just be looking at it right now for final render go for five yeah I'd say about fifty thousands a good amount and the caustic search radius this is the way that it searches for the photons and so increasing this helps it work basically but it can also both these parameters just like we did checked earlier on our light they can increase your under time so just you know be careful with that don't you know go all the way to the end otherwise you're gonna be waiting forever and let's let's just put the said yeah let's just leave it at five and so we've got ten thousand here for the max caustic photons and for our light we have two million and so let's move that to the side and like I said if we fire off an IPR or not going to see anything you know nothing going on and so let's pause that and I'll save a screenshot so we can compare and now if we do an actual render a bucket render and this will take a little bit longer because we enabled caustic so right now it's actually in the background creating the photons that have to get mapped out so this might take a little second and once it's done then you'll see it starting to do its thing and so what it's what actually does is it creates a caustic photon pass before the irradiance cache or before brute-force for all that stuff and so that takes a little while because it's a pre pass and so the higher you increase your settings obviously the longer you got to wait so here we go we already have caustics boom just like that in our scene and you see the difference right there so IPR again no caustic so you have to actually render it so if you zoom in here we've got caustics on the ground you know we got this cool little color change shifting the hue shift in the metallic objects are casting and it's actually being cast inside of the object and so that adds just a whole you know a whole lot more quality to it to the image but if you zoom in it's a little there's a little spot enos and so to get rid of that and if you want you can brighten it a little whole image so you can see it but generally in a dark dark light it looks better but like I said you could actually increase the multiplier so the multiplier here we have the multiplier let's just do something crazy use like five so that's half way to max and let's do that for both our lights so and let's increase now our number of photons that MIT to five million so that's half way also so it's going to emit a lot more photons this time so this is going a surrender time while this is just going to brighten how they look one is default that's what you know technically is the most realistic but for aesthetic purposes you can multiply it and have fun with it and then over here we'll actually increase just 40,000 and now our render times will be a little higher but also the quality of our caustics will be nicer so let's give that a give that a shot let's actually save that and do another render so this time I take a little longer as you can see it says down here photon mapping doing its thing so you got to wait a little longer while it maps out all the pre pass for the photon caustics or the caustics photons I mean and yeah that's I mean that's really how easy it is to get caustics in redshift and you just turn them on basically on the objects and on the lights and then make sure that your global redshift settings have caustics activated and okay here we go so that wasn't too long you know I mean for real caustics that's actually not that bad caustics generally takes forever to clean up also and so now we've got the irradiance cache going and as you can see it's already way brighter and that's just because I increase the intensity of the caustics to five which is way too much but you might want to use this high of a caustic illumination if your whole scene is brighter so if you're outdoors or something you know you're you can't you can't really see them that well so you might want to increase this and so there you go and now we have much smoother caustics but they're just obviously brighter because I increase the intensity and so let's say I actually do an IPR and I increase the GI light so the dome light now it's nice and bright the scene so if I had something like this or maybe even a little lighter go points point five that's maybe a little too bright point 0.2 0.1 yeah so now now this seems extra bright and you normally with a intensity multiplier of one the caustics might not be visible so under those circumstances I'm going to drop the settings real quick a little bit just so we can get a faster render this time and let's bring this down back to two back to two one and one on our other light for the multiplier and let's render so so you can see that if you have a one multiplier and you're seeing generally well lit you might have trouble actually seeing the caustics they might be too faint and so let's say you really wanted caustics or your client wants caustic source or you know aesthetically it looks you wanted them to pop out more that's where the intensity multiplier saves the day and so let's see so I mean they're there you know that they're they're in there they're doing their thing but see they're pretty subtle you know they're still here but the effect is really subtle and so I'm in a circumstance like this you know you might want to boost that up to four it still might be too bright but you know that's that's why you experiment and so if we do another render and now we have a multiplier for we should be able to see them better and so yeah that's that's really all there is to it you know just click on your object make sure that the visibility tag is turned on and that casts caustic GI is turned on so just got to make sure okay you know visibility is on cast caustic photons is on same thing with your lights make sure your lights have emit caustics on and finally just make sure your global settings have enabled caustics AC now we have really strong caustic effects and that's just because i'm increase the multiplier but the scene itself is you know the lights themselves are lighting the scene naturally at the strength that that I have on that and so yeah that's that's all there is the caustics thanks guys

Channel: Saul Espinosa

Views: 32,018

Rating: 4.9583335 out of 5

Keywords: Redshift render, redshift, cgi, vfx, 3d, autodesk, maya, digital art, art, tutorial, digital, caustics, training

Id: gMM0wi51IOs

Length: 14min 22sec (862 seconds)

Published: Wed Mar 15 2017