accelerad_rpict renders strange all black pixels in image

[Mohammad Ali Qorbani]

Hey everyone! I hope you are all well.

First I wanted to thank you sincerely for this notable and great project of Accelerad!

It's been a time that I have been working with Accelerad and mostly using your Accelerad_RT and I had no issues with Accelerad_RT, but my problem is with Accelerad_rpict where I can render images just as the Radiance_rpict although images rendered with Accelerad_rpict, have some strange looks, where in some parts of the image there would be some pixels all rendered completely black and among them, there is some cluster of pixels that form a circle that looks to have been correctly rendered.

I have attached images of the accelerad demo room, first one is the image of the default settings of the Accelerad demo file without any settings changed, the second one is a render inside of that demo room with -ab 4, and the third one is the same as the last one but with -ab 8 and the last image is a screenshot of a room I designed being previewed on Accelerad_RT. 

I am using the latest windows 10 update, and my graphics card is an RTX 2070 max-q design.
I have CUDA version 10.1 and Optix version 7.0.0 installed.

I was hoping if you could help solve this issue. Thank you in advance.

Best regards.

[Mohammad Ali Qorbani]

And here's the results that are printed in the cmd when I run test_accelerad_rpict.bat.

Accelerad 0.7 beta lastmod Mon 04/15/2019 by candela\natha on Candela (based on RADIANCE 5.2.b1862446a1 by G. Ward)

accelerad_rpict: OptiX 6.8.0 found display driver 461.9, CUDA driver 11.2.0, and 1 GPU device:

accelerad_rpict: Device 0: GeForce RTX 2070 with Max-Q Design with 36 multiprocessors, 1024 threads per block, 1185000 Hz, 8589934592 bytes global memory, 1048576 hardware textures, compute capability 7.5, timeout disabled, Tesla compute cluster driver disabled, PCI 0000:01:00.0.

accelerad_rpict: Geometry build time: 48 milliseconds for 26 objects.

accelerad_rpict: OptiX kernel 2 time: 122 milliseconds (0 seconds).

accelerad_rpict: Adaptive sampling: 9 milliseconds.

accelerad_rpict: Retrieved 124465 of 262144 potential seeds at level 0.

accelerad_rpict: K-means performed 7 loop iterations in 39 milliseconds.

accelerad_rpict: K-means produced 1012 of 1024 clusters at level 0.

accelerad_rpict: OptiX kernel 3 time: 17 milliseconds (0 seconds).

accelerad_rpict: Retrieved 162845 of 541696 potential seeds at level 1.

accelerad_rpict: K-means performed 6 loop iterations in 42 milliseconds.

accelerad_rpict: K-means produced 1017 of 1024 clusters at level 1.

accelerad_rpict: OptiX kernel 4 time: 12 milliseconds (0 seconds).

accelerad_rpict: OptiX kernel 1 time: 16 milliseconds (0 seconds).

accelerad_rpict: Retrieved 1017 ambient records from 1024 queries at level 1.

accelerad_rpict: OptiX kernel 4 time: 51 milliseconds (0 seconds).

accelerad_rpict: OptiX kernel 1 time: 10 milliseconds (0 seconds).

accelerad_rpict: Retrieved 1012 ambient records from 1024 queries at level 0.

accelerad_rpict: OptiX kernel 0 time: 12 milliseconds (0 seconds).

accelerad_rpict: ray tracing time: 773 milliseconds (1 seconds).

Accelerad rpict succeeded!

[Nathaniel Jones]

Hi Mohammad,

This question has already been answered here. In short, you can adjust your -ac setting in increase the density of ambient sampling density, which will fill in the black spots. Thanks for sharing your design in AcceleradRT. AcceleradRT does not use ambient sampling, and thus you should not see any unfilled patches there.

Nathaniel

[Mohammad Ali Qorbani]

Thank you so much, Nathaniel for responding this fast!

I could not find the keywords for my issue to search for in this forum.

I am going to try the new settings to solve my issue.

Best wishes to you.

[Mohammad Ali Qorbani]

Hello, again Nathaniel!

Thank you very much for your response, I increased the -ac parameter to 16384 and -aa parameter to 1.18, and the problem with the black patches were solved completely!

The resulting image looks like this:

the parameters for this rendering are:

-ab 4 -aa 1.18 -ac 16384 -ad 1024 -as 0 -lr 8 -lw .002

One other issue I am still facing with these images is the noise like pixels on the floor of the image, would you guide me to set my parameters in order to eliminate those noises?

Thank you in advance.

Best regards

[Nathaniel Jones]

Hi Mohammad,

The -aa parameter shouldn't be greater than 1, and usually is around 0.2. Start with that to see if it is causing the noise.

Nathaniel

[Mohammad Ali Qorbani]

Hi Nathaniel,

I used -aa 0.2, and some of those black patches are back in dark places of the image again. So I think that I should keep tweaking those parameters, Like decreasing -ar. 

Best regards