Path tracing accumulation artifacts
Path tracing accumulation artifacts
Hello guys,
Thanks for organizing this valuable forum!
Please, see the image - it is a path traced accumulated image with 15000 samples per pixel.
Each pixel color has the structure {double r, double g, double b}. At each PT pass these are accumulated: pixel.r += pass.r, pixel.g += pass.g, etc.
When I get some medium SPP of 3000-5000 the lighting on the walls is changing smoothly, but noisy. The noise is nice.
But when the path tracing accumulation process goes further and has more passes (> 10000) the lighting on the walls becomes clustered (pls zoom in the attachement img). I don't remember how this artifact is called. But please help me to eliminate the problem and get less problems with more PT passes.
Thanks for organizing this valuable forum!
Please, see the image - it is a path traced accumulated image with 15000 samples per pixel.
Each pixel color has the structure {double r, double g, double b}. At each PT pass these are accumulated: pixel.r += pass.r, pixel.g += pass.g, etc.
When I get some medium SPP of 3000-5000 the lighting on the walls is changing smoothly, but noisy. The noise is nice.
But when the path tracing accumulation process goes further and has more passes (> 10000) the lighting on the walls becomes clustered (pls zoom in the attachement img). I don't remember how this artifact is called. But please help me to eliminate the problem and get less problems with more PT passes.
- Attachments
-
- path_tracing_artifacts.jpg (31.52 KiB) Viewed 7319 times
-
- Posts: 83
- Joined: Thu Apr 24, 2014 2:27 am
Re: Path tracing accumulation artifacts
what is the rendered image resolution X , Y
Re: Path tracing accumulation artifacts
the resolution doesn't matter, it is 512x512 rendered and displayed. Other renderers for the same scene produce correct results
-
- Posts: 83
- Joined: Thu Apr 24, 2014 2:27 am
Re: Path tracing accumulation artifacts
well, I doubt something, so check it first, assuming a counter of integer type which is limited to 2^31, and it loops over the whole image (512 * 512) which is (2^9 * 2^9) , then you will have 2^13 samples per pixel before the counter goes mad (which is 8192 spp) , check this, if it is not the problem then I don't know what may cause this problem
Re: Path tracing accumulation artifacts
this is irrelevant calc, double type is used.
-
- Posts: 83
- Joined: Thu Apr 24, 2014 2:27 am
Re: Path tracing accumulation artifacts
well, test this, an output of 2k * 2k, with 1000 spp, if it generates artifacts then the problem is a false counter somewhere, the data is double or float for sure, but the sample "index" may be false
Re: Path tracing accumulation artifacts
it is the same with different resolution and then upscaling and downscaling the final result.
The sample index doesn't matter at all, since there are just 512*512 samples, and each time they are updated (actually 15000 times each).
The artifacts follow the light intensity distribution across the walls and corners, as you may notice.
The sample index doesn't matter at all, since there are just 512*512 samples, and each time they are updated (actually 15000 times each).
The artifacts follow the light intensity distribution across the walls and corners, as you may notice.
Re: Path tracing accumulation artifacts
Just add that applied gamma is 2.2
-
- Posts: 83
- Joined: Thu Apr 24, 2014 2:27 am
Re: Path tracing accumulation artifacts
hmm, for sure I can see where the errors in the image are, but I'm still concerned about the counter for some reason
if the samples are independent, then adding every sample with a different random number seed will give you correct image "so averaging 30k different 1 spp images should be equal to a 30k spp image"
from this point, try to store first 8k spp in one image, and the 2nd 8k spp in another image
if the samples are independent, then adding every sample with a different random number seed will give you correct image "so averaging 30k different 1 spp images should be equal to a 30k spp image"
from this point, try to store first 8k spp in one image, and the 2nd 8k spp in another image
-
- Posts: 89
- Joined: Thu Apr 11, 2013 5:15 pm
Re: Path tracing accumulation artifacts
The image is quite dark, at least on the devices I have handy, so I can't comment on the artifacts themselves. How good is your random number generator?