Why do small artifacts form near the shadow between the curtain and the paintings? they are like light dots (you can barely see them in the posted image, as the quality is low).
The render settings are quite high.
(if I use Brute force - Brute force, they disappear, but the rendering becomes very slow).
(upload://m2zwxDMTsXJakAW0qgi5yMXwNKM.jpeg)
It is Render Noise, a general Dilemma in Global illumination since your only light source is is through the window, V-Ray doesn’t have enough rays to bounce around the room to generate a noise-free image.
your best solution is to turn on the Denoise , Set it V-Ray and use the “Default” or “Mild” Presets.
These are the so-called “fireflies”. They can only be seen in that portion of the shade. Thanks for the advice. I’ll try.
What if I instead increased “max subdivs”, or the light cache subdvs?
You probably can, depends on how much improvement you can see. previously in the old days of V-ray we used something called light portal at the window that helps the GI rays to be concentrated and emitted from the window. Another illegal trick is to use a rectangular light fixture that matches the window in size and the color temperature of the skylight. (It won’t make your rendering “physical” but it may help getting some of that controlled.
Thanks.
I knew these tricks. I prefer to make a realistic environment that is based on physics.
(I increased the HDRI light intensity value, but it seems that not enough light ever comes in.
In my opinion, the Vray people should work on these aspects a little).
I tried: it is solved by increasing the “max Subdvs” parameter. Rendering times increase a little but those annoying bright dots disappear. Or, as you suggested, use a denoiser.
Good to hear, thank you for sharing the solution.
Only for the record - using a dome light for the environment is also recommended and additional enable “adaptive” for the dome light.
Some times I got fire flies per RTX, but not per Cuda.
Adaptive is enabled. As I was saying, I increased the “max subdvs” parameter and the fireflies disappeared.
Or use an unbiased renderer and not deal with this 
It would only be perfect if it were fast: waiting a whole day to get a clean render is not the best!
If you have a better processor or even a graphics card with higher performance, I would try Thea render or Bella. Thea in Presto mode is generally faster than V-ray brute force and definitely has better results. Although Bella in Saturn mode only works on the CPU, it is also faster or as fast as v-ray according to my comparison. Both of these engines have more photorealistic results than v-ray at maximum quality (I’ve compared it a lot). Of course, the full unbiased mode in Maxwell render, Thea TR1/TR2 and Bella Atlas is very slow and you would have to wait a day for a perfect result, but with denoisers, the calculation actually became much faster.
At the moment, I’m only using Bella render, which with its Saturn solver is 98% the same as Maxwell (except full caustic), but much faster I think. I would only use full unbiased rendering with a powerful denoiser and a very powerful CPU. 
It would be interesting to be able to compare a simple scene, even just a still life image, between Vray and one of the render engines you’re talking about. I render with Vray and prefer to use brute force: with light cache or irradiance map the results are discreet, nothing beautiful.
Maxwell is said to be very slow (although the best); I know Thea Render and Bella but I didn’t want to use them because I’m now used to Vray.
Could you say that my render, the one posted above, would be better if it were rendered with Bella or Thea render? Do you have this certainty?
I think you’ll see the quality of the renderer on simple scenes. It was on them that I compared the speed and photorealistic quality of the rendering program. The more complex the scene, the easier it is to hide imperfections in the visualization. I also always used brute force in v-ray, on the other hand, the render is often significantly slower and does not reach the quality of unbiased engines.
I don’t know if Maxwell is the best in terms of quality. This was true years ago, but today there are programs of similar quality on the market (Thea TR1/TR2 mod, Bella Atlas, maybe Indigo). I don’t like the FIRE preview mode on Maxwell, it falls short of production render quality and is therefore unusable for me. Also, Maxwell’s response in Rhino is slow. I’m afraid Maxwell is simply outdated.
If you have a good monitor (4k resolution and good colors) and you render the same scene in Thea render or Bella, the quality will definitely be higher in my opinion. The scene will not look so “flat”. Without a direct comparison of the 4k render, however, the difference will not be large. V-ray is certainly a very high-quality program. But as I write, at the moment I only use Bella because it is easy to set up and has definitely the best results at the given time. In addition, the preview of the render is the same as the final calculation and this is a huge advantage that many do not realize.
I’ll try to do a quick comparison on a simple product design scene between v-ray and Bella. Settings and rendering time as similar as possible.
I use V-Ray daily and together with 2x3090 and 2x2080ti I’m glad with speed and quality. Most I use LC+BF. I’m very happy with the stable quality over a wide range of scenes.
And don’t forget, a good render plugin provide a lot of little tools, features and frequent updates. I see no reason why some one shouldn’t be happy with V-Ray.
I use both Twinmotion and Vray. Twinmotion for the quick and dirty studies, while V-ray is for the beautiful and tasteful work.
also I’m using a single A40 (Coparable to 3090) and I’m very satisfied with the speed.
I think Vantage is pretty nice for the quick and dirty, and its easy to go to full VRay from there. Pricing is a bit hefty tho.
The new Vantage 2.1.1 floors all the other realtimers. The issue is. You need a V-Ray license to create a vrscene.
You can still use Vantage to import FBX but I think this is going to complicate the process even more.
Yes its basically a VRay add-on (which is more expensive than VRay itself). But for VRay users its definitely nice to have.
