I wanted to add some more light (couple area lights) to my scene in addition to my HDRI. However, adding a ‘‘plane’’ mesh for the lights drastically increased my render time 8-10 times more. This happens only with the plane. I removed the materials from the plane to see if it makes a big difference but no. The plane has only smooth shading because of the beveled part to make it look smooth. I don’t need any shadows so I turned it off (both for my object and the plane) unchecking shadow through properties under ray visibility. However, no change and I’m not understanding why this increases render time by so much.
Another issue is that I have another background and I want to make the plane invisible. However, when I uncheck camera in properties under ray visibility, it becomes invisible and the reflections are still on my object (character) but it is not as shiny anymore. It’s as if more roughness is added to it and it becomes kind of more matt. What is the problem here?
Are you using an emissive plane as an area light? You could just use an Area Light emission is definitely slower than normal lighting, if you change that plane to an area light, you should see speed ups
Could you please explain it simpler if you can as I’m kind of new to Blender I have 3 area lights - left, right, and top. And I just put a normal plane - Shit + A → Mesh → Plane (with Principled BSDF).
My specs are RTX 3060 GB, Ryzen 7 5800H, 16GB. Without the plane, with like 10000 samples, rendering a frame would take less than a minute. Now with the plane, it takes almost 8 minutes. And this is only happening because of the plane. When I remove it, render time is back to normal. I removed all the lights and just kept the plane and the render time is still the same. I realized this is happening only because of this simple plane but can’t figure out why
I just have my object (my character). Wait, let me send you the scene As I said, this happens only with that plane. Without it, render time is back to normal.
By the way, could you also check that making the plane invisible makes the object a little more matt while keeping the reflections as they are. Don’t understand why this is happening also…
When you talk about the plane, you mean the curved background you put under and behind the sphere? If yes, that performance drop is completely expected. Any area of your render that has direct view to the sky will render extremely fast, because Cycles doesn’t have to intersect rays of light with polygons. As soon as you cover the whole background, suddenly the rays coming from the camera all have to touch geometry, which adds a lot of rendering complexity. That’s simply the way ray tracing renderers work: they care a lot more about the layout of your scene, the materials complexity and where the light sources are placed than they do about the number of polygons. If you create a scene with a simple cubic room with a lamp and a camera inside, it will take a surprising amount of time to render for how simple it looks, because the screen is completely filled by the polygons and also the light rays keep bouncing between the walls.
Also, do you really need 10000 samples? In most scenes you would usually be fine with 1000 samples with denoising activated.
Something I can add, though I don’t think it has that much of an impact here, is that Cycles (and lots of similar renderers) struggle with long and narrow polygons that are in a diagonal. That’s because Cycles optimizes renders by placing bounding boxes around polygons, and having them in a diagonal makes the boxes huge and makes them overlap. If you place a bunch of long narrow cylinders in a scene and make them diagonal, the render times will go way up. Then, if you divide them until the polygons are roughly square, the render times will be much faster even though you have more polygons.
For your other problem, I am not sure what you mean. You are deactivating camera visibility on the ground plane? On my side, I don’t see a difference in the sphere when doing that.
Well, actually not even 10K samples were enough because there were still fireflies on the object. However, it was with a different HDRI. This one seems to be ok with a couple thousand samples only.
As for the other problem, with the sphere it looks the same to me as well but with my character, it just seems more matt (less shiny as though roughness is increased). I hope it just seems like that to my eyes only The sphere was just a test file. I actually have a character instead of the sphere I sent
BY THE WAY, as I mentioned, I have another background (will make the plane invisible) and when the plane is invisible, render time is back to how fast it was before I guess the problem is solved then?
emission is definitely slower than normal lighting, if you change that plane to an area light, you should see speed ups
I have 3 area lights - left, right, and top. And I just put a normal plane - Shit + A → Mesh → Plane (with Principled BSDF).
The sphere was just a test file. I actually have a character instead of the sphere I sent