Hi there! Corona newbie here, I need help with my renders, they look meh

[Valerie95]

I'm using Corona for 3ds max 2024 and I've been struggling with obtaining a realistic looking render for quite some time now, I've tried watching many tutorials about many aspects of my scene, and in some cases it did help with smoothing the overall aspect BUT, I still find it lacks realism, it's just...strange. One thing that I really struggle with is the natural lighting, as you can well see from the image I attached; I've tried many times with different hdri maps, calibrating it first with the mtl override and then with materials on...it's just quite not right.
I know there are some major problems with some models: the entrance door and the antique sideboard. The first is only temporary and would be a flush to wall door, while that sideboard is the only decent looking (and free) 3d model I found. I also know that certainly some materials are not well mapped.
And these are the things I know that don't really work with my model...then there could be an abyss that I don't know about, so I will also link the file for you more navigated people to explore it and see what you can sort out...I'd be really grateful, because I'm out of ideas :((

https://www.dropbox.com/t/rmG5PpPMhmZvWZ1w

[Nejc Kilar]

Howdy and welcome aboard!

To be honest, for a self proclaimed newbie, this is a friggin terrific start, kudos!!

In my opinion you got all the basic ingredients in there already. For example the lighting feels natural to me although from a "creative director's POV" maybe a little too "everyday" maybe but that is potentially highly subjective of a comment.

The materials are all solid but I think there is room to improve them by adding details on them. Maybe add a little extra sheen on the sofa, put some imperfection maps for the sheen amount so it looks like somebody sat on it... Maybe dirty up the sofa with some dirt overlay textures in the base color slot etc etc. I think that'd help sell this in terms of realism.

Much the same goes for the rest of the materials really, maybe add a little tiny bit of imperfections on those pristine walls (on the base color and the reflections) and some wet wipe imperfections on reflective surfaces (tables).

I'd also double check the kitchen elements, they seem like the smoothing is off on them (they look oddly curved yet flat at the same time). I'm not a kitchen expert at all but there's also seemingly very little detail for when it comes to handles on those cabinets too. And if you continue to dress up that area with kitchen elements (or a small light) it'll add a bit of additional creative flare to it all which sometimes helps with realism as well.

So thats just my first impression, hopefully I can be of more help if you have any sub questions and I'm also excited to hear what other folks might have to say.

Cheers!

[Valerie95]

Hi there Nejc!

First of all thank you for your reply and your feedback about the scene, I was losing hope someone would look into my post ahahah
I'll try everything you pointed out, about "dirtying it up" a little bit, especially the antique sideboard and the sofa which I'm really not happy about.
I'll mention something I forgot, which is that the scene is actually a real space, it's my new family house so it all started with trying 3d visualization to check out furniture combinations, colors, volumes etc. It's a real interior project and I used it as an opportunity to try and upgrade my 3d modeling and rendering skills, and I decided to try out Corona.
About kitchen panels: the single lateral ones open with a push and pull mechanism so they don't need handles, i haaaaate them ahahah. I only recently discovered the chamfer modifier, so prior to that I always used the mesh smoothing and I guess that's the strange effect you're describing, I'll correct it.
That being said there are two aspects which I'm actually concerned about: the lacking of "atmosphere" and the rendering time. I attribute the reason for the atmosphere problem to the lighting, but maybe I'm wrong; it's just that the furniture seems to be in a place "without air", as if the light is not passing through the infinite number of particles...I don't know if I'm making sense. It looks like a drawing with realistic ambitions while what I'm aiming for is a photorealistic level. I think it may be because I'm having troubles in regulating the HDRI map, even though I followed to the letter many tutorials I watched on the topic. Or maybe the problem is about how the materials interact with the lighting? I don't know.
About the rendering time, that render picture I attached took about 24h to make it...and since the noise, especially in the corner of the kitchen, wasn't getting better, I stopped it. I know that my scene is very heavy and I probably could do something to optimize it (I'm all ears if you have any tips on it) and maybe my computer doesn't have all the right requirements to make a render in a decent amount of time but for other projects it wasn't such a problem and the results in comparison were more satisfying. So I'm splitted into 1) doubting there's a more hidden problem in some settings that I don't know about or 2) that If I optimize the scene and let it go until almost any noise vanishes and image is clearer THEN I'll have my photorealistic render :\

[maru]

About the rendering time, that render picture I attached took about 24h to make it

That doesn't sound right. :O

What is your CPU model?

I'm pretty sure those curtains are slowing rendering down. You could try using a Rayswitch Material (https://docs.chaos.com/display/CRMAX/Corona+Rayswitch+Material) to make them visible directly but prevent them from affecting global illumination (or at least altering the way they are affecting it).

A random idea (which could accidentally result in a more attractive render and shorter render times) - how about turning day into night and turning on various interior lights? :)

[Valerie95]

Hi Maru!

I'll write down all of the characteristics of my computer: it's an Asus Tuf Gaming model (FX505G) with Intel core i7 8th generation, Nvidia geforce GTX (1050 Ti) with 250GB of memory in the C unit and 16GB RAM.

It's interesting what you're saying about the curtains; because the scene is very heavy and the RAM in my PC is not totally capable, I'm sure you all know that in these cases 3ds max pops up a warning saying that the system is running low on RAM and then proceeds to list the capacity of virtual memory made available and the heaviest objects and texture in the scene. It always listed various things, but never the curtains, and yet they are the most fastidious object to render (also from other camera angles with different exposure value etc.). I will definitely follow your suggestion and see what happens. Anyway it's quite strange, because I only have problems with the living room model; the other rooms I rendered look quite realistic and noise free.

About making it a night render I'm really still eager to try and get a photorealistic, neutral daylight render, because I'm building up a portfolio showing, among other things, this interior project and I want to show the room in natural lighting because...well architects and interior designers prefer it that way :\

[TomG]

Aha, if you are getting a RAM warning, then that would explain the long render times, I don't think I saw information about that before. Some things don't take much RAM, but do involve a lot of calculations for the render engine (like passing light through translucent curtains and continuing it on into the scene and bouncing around), which is why they were a suggestion; but that said, any complexity in calculation from that will be outweighed by the speed impact of low RAM now that we know you have the low RAM warning.

BTW on CPU we'd need the particular model rather than just the generation, it looks like that laptop comes with an i7 - 8750H, which in itself is not a fast processor (https://benchmark.chaos.com/corona/v10/scores?index=1&order=desc&by=rays&my-scores-only=false&search=i7+-+8750H ), so having that then hit with low RAM will definitely lead to sub-par performance.

None of this relates to the quality of the image of course, but reducing RAM usage would be a major help for your render time here (or adding more RAM, if the laptop supports it ).

[Nejc Kilar]

Glad you've found the feedback useful Valerie!

Regarding performance I completely agree with Maru and Tom - that might be a slow(er) CPU for today's standards and if you couple it with running out of memory (RAM) then you'll really have trouble rendering this one out :)

On the more artistic side of things, I really think its good that you've started with something that is an actual place you can visit in real life. When I started out one of my earliest projects was trying to recreate the office space I had - really not that visually stimulating as a render per say but it did give me an opportunity to try and recreate all the objects (and the space itself) pretty much with the same or similar details I could see. I think thats a cool approach to things because you can pick stuff up and just go to work until the render looks convincing enough given what you have in your hands. Takes a ton of time but imho it is very much worth it.

As far as the "atmosphere" I think that might actually come down to your tone mapping as well. Try playing around with some of the LUTs Corona comes with and see if that helps.

Oh and the chamfer modifier, try setting it to "smooth chamfers only". That'll probably help.