[flow_default] Transcription: 01. Importance Samples.json

transcriptions/01. Importance Samples.json

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+{
+  "audio_file": "01. Importance Samples.wav",
+  "text": "In this video I'm gonna explain the multiple importance sample settings and how to set up the artificial light sources in the interior scenes. So in Blender we can have two sorts of artificial lights. We can either press Shift A, go to the lights and add one of the lamps except of the sun which goes for the exterior. So let's say the spot lamps, which we already have in our scene by the way, these two, but we can also have mesh lights. So a mesh light is actually a normal object, one of those with a shader, emissive shader applied to this object. Here you can see we have two spot lamps, the IS lamps, which by the way can be added from the model manager under the materials. You can find the IS category in our store and download those setups. So these are basically the mesh lights, the mesh elements, those circles with a special node setup applied to them, but we can also use something much similar. So just the emission shader if we want to have the most simple mesh light source. The reason I'm explaining this is those two types of lights behave differently. If we have spot lamps in our scene, usually nothing changes if we add let's say an area lamp. As you can see here, if I scale it up, let's enable the overlays. So we have a better preview. If I scale it up, if I increase the energy of this lamp, except of having this huge radiation, nothing really changes in the scene. So those spot lamps work normally. Let's delete this area lamp. But if I add a mesh plane and if I apply an emissive shader to it, so I'm adding a new material and as a surface, let's choose the emission. You can see the spot lamps we still have in our scene are gone. And why is that? Well, first of all, they are not gone. They are actually rendering. But if you have the clamping settings set up quite high like here, they will be simply cut out of the rendering because when we disable the clamping, you can see right now Blender tries to somehow calculate those lamps in our rendering. If we increase the number of samples, this will continue. The problem is those lamps are rendering as those ugly hot pixels. So the clamping settings, if we set them to any value, they basically cut away those pixels from the final result. What's also interesting, if I start scaling down this plane, you can see the lamps are becoming visible again. So this is pretty interesting if you ask me. So the reason for those artifacts are the multiple importance samples and if we go to the material settings here, we can find them under the settings and surface and this is the option I'm talking about. So if we enable or disable this for some of the light sources, we are basically telling Blender to focus the rendering power, the computing power on those light sources. In a situation where we have multiple small light sources like the ones here and here, having this option enabled is a must because otherwise Blender won't be able to find and render these lamps correctly. So if I disable this for this one spot lamp here, you can see it's basically gone. And again, if I remove the clamp settings, this lamp is actually rendering, but Blender has a huge problem finding its source. So that's why it's spraying all of those hot pixels. So if it sounds a bit complicated, well, it actually is. I would say a rule of thumb in setting up this kind of light sources is if we have mesh light sources for small lamps, simply enable the multiple important samples. has no problem in general to find it and to render it. So we can tell, well, please omit this object in your calculations and focus only on the objects that have this option enabled. So yeah, that's basically what's happening. Blender has no problem with finding this light source. If we move it anywhere around the scene, this will now work together with all of the other lamps. In general, in the previous Blender versions, it seemed like the normal lamps, like the Spotlamps here, needed the same settings as the small mesh light sources. So we always had to include the multiple important samples. Right now, from what I've tested tested it seems like it really doesn't matter for the spot lamps. So the multiple important samples are really important for the mesh lights. So objects with the emissive shaders as this one here or as these two IS lamps we have. So I really hope this clears up this topic for you. Again, there aren't any fixed settings except of this rule of thumb I just gave you. The way you should set up those multiple important samples strongly depends on the scene you're working on. So if you have multiple IS lights in your scene, you might try just by trial and error, disabling or enabling these settings for them and find the best solution. But as I said, it really strongly depends on the scene you're working on. Just keep these settings disabled for the big mesh light sources and keep it enabled for the small light sources.",
+  "language": "en",
+  "confidence": null,
+  "duration": 432.7
+}