Hi everyone!
I’m having a lot of issues with cycles. I’m able to select properly my gpu to render with cycles (with a gtx1650). That being said, it feels like my render time are very slow. It takes about 1 minute to render my 1080p image, with 128 samples.
Also, the image is really horrible, without denoising it looks like this (at 50% resolution):
I’m not sure why it is so much grainy… Did I miss anything?
Thanks!
It must be samples numbers and 50% is low for final rendering. Though at this stage, not complete, speed to check out the general effects is probably more useful than a great render. Though that role is these days more what evee is for.
One minute is next to instant! for Cycles. On the old course, my rabbit scene took 18 hours. Much more in it than this obviously. Good renders are in hours not mins.
Ok, so the render time is probably normal then. But still, the noise I have is significantly more important than when is seen in the lecture… How something still wrong in my settings?
Ah just noticed 128 samples, that would seem it is not as good as I would expect. FedPete has mentioned to others low light makes for noisier renders. It does seem the light is back lighting your base. Try moving the light round to the front, (to one side). The classic three point lighting has two from the front one from the back. Main, front fill, back edge highlight.
Hmm, I disabled all my lights and added 3 points lights as you suggested. I made sure they were quite bright to see the difference in noise and, althought the resulting render is better, it’s still quite noisy:
even by doubling the samples to 256, I don’t see much of an improvement:
No to make the render faster, I rendered at 50% resolution. I don’t think the output image resolution changes the noise very much. Here is what it looks like at 100%:
Better but not as good as I would hope. Yes, 50% is a big drop it takes 4 of your 960x574 to cover the area of the 1920 x 1080.
All I can suggest is adding the blend file in here so that FedPete or Mark
_Carlyon the assistant tutor can check out other parameters.
Just checking, the obvious, these are renders, not rendered viewport captures? Just occurred to me viewport renders will be at the viewport sample rate not the render rate. Remote idea.
Two things that helped me get rid of the noise:
and / or the faster way
The images are renders (as implied by the fact that I’m rendering only 50% of the resolution). Here is the blend file:
animated-lamp.blend (1.4 MB)
@dsthilaire Can be anything, but intriguing indeed.
Fact is, GPU does not always win over CPU. While GPU is a number mover, mapping a texture on a face is a breeze!
But when you rely on heavy procedural node texturing or ton’s of reflection (number crunching). Then probably a CPU with multiple hyperthreads, will win the race. Not all (it think most) modifiers and texture nodes, will use CPU. Because they need CPU instruction set (more maths).
So I’m curious how you build the node texture?
There is a lesson in the Blender 2.79 course, where you, as a student, are asked to render the BMW car. A Blender 2.79 benchmark. Also they (Michael) instructs you to tweak the Tile size. Which is one render square, part of the render executed by a GPU or CPU thread.
CPU 8 core, can work with 8 tiles at the same time. for a GPU you see one tile.
I do not know if this is part of the new blender course. But here is an old thread gtx580
The trick is for each project, is to tweak this tile (memory) setting.
Render scene CPU with tile size 32, 64, 128, 256 …
Render scene GPU with tile size 32, 64, 128, 256 …
Write down render times and look for a optimum.
But this is per project, depending on used modifiers, textures, node textures …
This number depends on the way your project is build. And has something to do with memory and therefore render speed.
The Blender organization, has a online Blender benchmark test. Where you can compare you hardware with others. Maybe your performance is low due to other hardware, video card driver problems.
See Introducing Blender Benchmark
You’ll downloading a special version of blender, including benchmark project.
But I think you need to be a blender member …?
I did it, but I pay blender the minimal 5,- blender support fee. And I have a Blender ID membership.
Then samples: 128 is really low. But for many projects, with enough light this can be sufficient (with or without denoising). I can not see your complete project. But if the lamp stands in a box (mimicking a room), you are missing the environmental light source (which has an huge effect for overall lighting).
So it’s complex, and therefor
Report back if you know more.
I see your .blend file. It has 3 faces as walls (blocking environmental light).
Your tile size 256px, is for my machine huge.
My laptop Win7 Intel Core i7 - CPU Render time 1m 25sec. - The same render noise as you do.
Tile size 96px CPU render time 1m 09sec - same render noise (FASTER)
When I throw away the wall and other things out of the render. Only lamp base 35 seconds render time and less noise.
So your reflecting wall light, adds the noise. Meaning, it’s difficult with low samples rate, for blender to make a good render sample, in your particular case…
Your lamp plane is also low on power. 30w + low environment is difficult at low samples to get noise less renders.
Your texture is 50% metal, so highly reflective. Light bouncing on and of the wall is thus reflecting light from the wall which has lower intensity that the light of 30w.
Lamp shines on foot, reflects to the wall, bounces back to the lamp foot into the camera.
That path is to long for low samples rate and low lamp 30 watts, to make a nice render.
Like, making a picture at night time.
Drop metal !! or increase samples 1000, 2000 …
@FedPete Thanks a lot for this great answer! I didn’t consider that the environment would be a factor of all the noise I was seeing, but it makes sense! It’s funny because cycles is kind of supposed to be a “you use it and it just works” renderer, but it requires fiddling with just as much as Eevee does (if not more)!
In any case, this was a lesson rich in learning! Thanks a lot @FedPete, @Marcello and @NP5 for your support! <3
Yes, Cycles is much more fiddling. And still “You uses it and it works”, but you need to use a huge sample rate (very slow renders).
Eevee also, but the options are less. And therefore less accurate.
That said. Blender is just a tool. Only the end result counts! And takes of lot of creativity, knowledge of lighting, design, composition, camera handling, rule of third, story telling, where lies the user attention focus … mostly stuff nothing to do with Blender.
Have fun, show us your work.
This topic was automatically closed 24 hours after the last reply. New replies are no longer allowed.
