Render very poor compared to Viewport (far away object)


I’ve got a project which im ready to render. But when I do, everything is ok apart from the cube with light emitters. Such poor, low res lights, but everything else looks as it should or how it looked in the viewport?

What am i doing wrong? Is it the volumetric cube (turned this off, same result)

Heres the render result

I cant send or upload the blender file as its too big - but i can screenshot anything you need to see to suggest what is wrong.

I think its something about the cube seeing as its the only object that has an issue

please help i spent so much time learning to do this


ive noticed this problem on other objects
Screenshot 2021-02-08 100614

Screenshot 2021-02-08 100739

cube looks fine in viewport

Are you using eevee? Try increasing your samples or scene resolution

Hey thanks for replying

I’m using cycles

Should I do the same for that? Samples is at 150 instead of 128

Looks like denoising could be the problem try turning it off. Denoising can create artefacts like this.
I have made an example with an emission texture similar to yours:
rendered without denoise:

Rendered with denoise:

Note the same artefacts that you have.
Sometimes denoising only results in adding artefacts!

You should try 15000 if you have this kind of noise. Or fake it. Make a separate render of the cube and add it in the compositor.

Cycles is full of noise, that is what your seeing. Yes increasing the samples would reduce the noise. (*should). It will make the speed horrible though.

hey thanks, i went with it, did some denoising and tidied up in photoshop =/

ive seen people do 400-800 samples which is mad but yeah one day ill have a supe’d up GPU/CPU to make that quicker