Jan Walter July 18, 2023 [TRACE] #pbrt-v4 #denoise
The last part (PBRT v4 - Part II: OptiX
denoiser) introduced the OptiX
denoiser. Let's apply this to another scene, the Watercolor
Scene.
The scene comes with 18 camera perspectives, so there is a lot of
material to play with, but I have selected only two of them for this
blog post. I did render both camera perspectives (camera-9 and
camera-13) with 4096 samples per pixel (spp), copied the
results into a subfolder (spp4096), and applied the OptiX
denoiser there.
$ pbrt --stats --spp 4096 camera-9.pbrt
...
$ pbrt --stats --spp 4096 camera-13.pbrt
...
$ cp camera-9.exr spp4096/camera-9-4096spp.exr
$ cp camera-13.exr spp4096/camera-13-4096spp.exr
$ cd spp4096/
$ imgtool convert camera-9-4096spp.exr --outfile camera-9-4096spp.png
$ imgtool convert camera-13-4096spp.exr --outfile camera-13-4096spp.png
$ imgtool denoise-optix camera-9-4096spp.exr --outfile camera-9-denoised-4096spp.png
$ imgtool denoise-optix camera-13-4096spp.exr --outfile camera-13-denoised-4096spp.png
For convenience I provide a
watercolor_spp4096.zip file with the
OpenEXR and PNG files involved:
$ unzip -l watercolor_spp4096.zip
Archive: watercolor_spp4096.zip
Length Date Time Name
--------- ---------- ----- ----
0 07-18-2023 06:28 spp4096/
1003526 07-18-2023 06:23 spp4096/camera-13-denoised-4096spp.png
1338772 07-18-2023 06:28 spp4096/camera-13-4096spp.png
764671 07-18-2023 06:23 spp4096/camera-9-denoised-4096spp.png
1106958 07-18-2023 06:28 spp4096/camera-9-4096spp.png
18447347 07-18-2023 06:19 spp4096/camera-13-4096spp.exr
17286470 07-18-2023 06:19 spp4096/camera-9-4096spp.exr
--------- -------
39947744 7 files
It's best to download those files and compare them yourself using your
favourite image viewer.
Camera 13
The biggest visual difference between the denoised version and the
original rendering for camera 13 are the two glasses (one filled
with colored water) and the floor pattern:
$ imf_diff -d -f camera-13-4096spp.png camera-13-denoised-4096spp.png diff-002.jpg
differing pixels: 28.785% (215885 of 750000)
average difference: 1.823%
maximum difference: 13.865%
Summary: Many pixels differ.
== "camera-13-4096spp.png" and "camera-13-denoised-4096spp.png" are different
Camera 9
For camera 9 the difference is really hard to catch by eye. If you can
spot them it's most visible in the specular highlights of the cans
(and the wavy parts). But the shadows on the white walls are
noticeable less noisy.
$ imf_diff -d -f camera-9-4096spp.png camera-9-denoised-4096spp.png diff-001.jpg
differing pixels: 10.669% (80020 of 750000)
average difference: 1.169%
maximum difference: 6.207%
Summary: Many pixels differ slightly.
== "camera-9-4096spp.png" and "camera-9-denoised-4096spp.png" are different
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