Nodes: Implement Gabor noise #121820

Omar Emara · 2024-05-15T12:43:00+02:00

Omar Emara commented

2024-05-15 12:43:00 +02:00

This patch implements a new Gabor noise node based on [1] but with the
improvements from [2] and the phasor formulation from [3].

We compare with the most popular existing implementation, that of OSL,
from the user's point of view:

This implementation produces C1 continuous noise as opposed to the
non continuous OSL implementation, so it can be used for bump
mapping and is generally smother. This is achieved by windowing the
Gabor kernel using a Hann window.
The Bandwidth input of OSL was hard-coded to 1 and was replaced with
a frequency input, which OSL hard codes to 2, since frequency is
more natural to control. This is even more true now that that Gabor
kernel is windowed as opposed to truncated, which means increasing
the bandwidth will just turn the Gaussian component of the Gabor
into a Hann window. While decreasing the bandwidth will eliminate
the harmonic from the Gabor kernel, which is the point of Gabor
noise.
OSL had three discrete modes of operation for orienting the kernel.
Anisotropic, Isotropic, and a hybrid mode. While this implementation
provides a continuous Anisotropy parameter which users are already
familiar with from the Glossy BSDF node.
This implementation provides not just the Gabor noise value, but
also its phase and intensity components. The Gabor noise value is
basically sin(phase) * intensity, but the phase is arguably more
useful since it does not suffer from the low contrast issues that
Gabor suffers from. While the intensity is useful to hide the
singularities in the phase.
This implementation converges faster that OSL's relative to the
impulse count, so we default to a lower value of 8 and cap the input
at 16. We might even look into removing that input for simplicity.
This implementation does not implement anisotropic filtering.

Future improvements to the node includes implementing surface noise and
filtering. As well as extending the spectral control of the noise,
either by providing specialized kernels as was done in #110802, or by
providing some more procedural control over the frequencies of the
Gabor.

References:

[1]: Lagae, Ares, et al. "Procedural noise using sparse Gabor
convolution." ACM Transactions on Graphics (TOG) 28.3 (2009): 1-10.

[2]: Tavernier, Vincent, et al. "Making gabor noise fast and
normalized." Eurographics 2019-40th Annual Conference of the European
Association for Computer Graphics. 2019.

[3]: Tricard, Thibault, et al. "Procedural phasor noise." ACM
Transactions on Graphics (TOG) 38.4 (2019): 1-13.

This patch implements a new Gabor noise node based on [1] but with the improvements from [2] and the phasor formulation from [3]. We compare with the most popular existing implementation, that of OSL, from the user's point of view: - This implementation produces C1 continuous noise as opposed to the non continuous OSL implementation, so it can be used for bump mapping and is generally smother. This is achieved by windowing the Gabor kernel using a Hann window. - The Bandwidth input of OSL was hard-coded to 1 and was replaced with a frequency input, which OSL hard codes to 2, since frequency is more natural to control. This is even more true now that that Gabor kernel is windowed as opposed to truncated, which means increasing the bandwidth will just turn the Gaussian component of the Gabor into a Hann window. While decreasing the bandwidth will eliminate the harmonic from the Gabor kernel, which is the point of Gabor noise. - OSL had three discrete modes of operation for orienting the kernel. Anisotropic, Isotropic, and a hybrid mode. While this implementation provides a continuous Anisotropy parameter which users are already familiar with from the Glossy BSDF node. - This implementation provides not just the Gabor noise value, but also its phase and intensity components. The Gabor noise value is basically sin(phase) * intensity, but the phase is arguably more useful since it does not suffer from the low contrast issues that Gabor suffers from. While the intensity is useful to hide the singularities in the phase. - This implementation converges faster that OSL's relative to the impulse count, so we default to a lower value of 8 and cap the input at 16. We might even look into removing that input for simplicity. - This implementation does not implement anisotropic filtering. Future improvements to the node includes implementing surface noise and filtering. As well as extending the spectral control of the noise, either by providing specialized kernels as was done in #110802, or by providing some more procedural control over the frequencies of the Gabor. References: [1]: Lagae, Ares, et al. "Procedural noise using sparse Gabor convolution." ACM Transactions on Graphics (TOG) 28.3 (2009): 1-10. [2]: Tavernier, Vincent, et al. "Making gabor noise fast and normalized." Eurographics 2019-40th Annual Conference of the European Association for Computer Graphics. 2019. [3]: Tricard, Thibault, et al. "Procedural phasor noise." ACM Transactions on Graphics (TOG) 38.4 (2019): 1-13.

👍 2 👀 3 🎉 1

Omar Emara added 7 commits 2024-05-15 12:43:11 +02:00

Omar Emara added 2 commits 2024-05-16 15:10:51 +02:00

9863d0c321 Merge branch 'main' into gabor-noise

759972d5eb Add Cycles support

Omar Emara added 1 commit 2024-05-16 15:12:21 +02:00

eeb3b2363f Format

Omar Emara added 1 commit 2024-05-17 10:46:19 +02:00

af7d26c06d Fix wrong enum values

Omar Emara added 1 commit 2024-05-17 16:08:53 +02:00

59ecb9f5a7 Compute noise phase and intensity

Omar Emara added 4 commits 2024-05-22 13:06:18 +02:00

09f35517b5 Merge branch 'main' into gabor-noise

8282467227 Merge branch 'main' into gabor-noise

a68a910e72 Merge branch 'main' into gabor-noise

c9b18a9e84 Normalize noise

Omar Emara added 1 commit 2024-05-23 17:00:46 +02:00

7493196bad Validate inputs and fix normalization

Omar Emara added 1 commit 2024-05-23 17:54:05 +02:00

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6b3d358e86 Cleanup

Omar Emara requested review from Brecht Van Lommel 2024-05-23 17:54:23 +02:00

Omar Emara requested review from Sergey Sharybin 2024-05-23 17:54:23 +02:00

Omar Emara changed title from ~~WIP: Nodes: Implement Gabor noise~~ to Nodes: Implement Gabor noise

2024-05-23 17:54:28 +02:00

Omar Emara added the

 @ -0,0 +21,4 @@
   b.add_input<decl::Vector>("Vector").implicit_field(implicit_field_inputs::position);
   b.add_input<decl::Float>("Scale").default_value(5.0f);
   b.add_input<decl::Float>("Impulses").default_value(8.0f).min(0.0f).max(16.0f);
   b.add_input<decl::Float>("Frequency").default_value(2.0f).min(0.0f);

 @ -0,0 +35,4 @@
       .subtype(PROP_DIRECTION);
   b.add_output<decl::Float>("Value");
   b.add_output<decl::Float>("Phase");
   b.add_output<decl::Float>("Intensity");

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