Tangent Space and Ambient Occlusion by ssheorey · Pull Request #7364 · isl-org/Open3D

ssheorey · 2025-11-07T00:07:02Z

Type

Bug fix (non-breaking change which fixes an issue): Fixes #
New feature (non-breaking change which adds functionality). Resolves #
Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

Normal maps are saved in tangent space. This PR adds functions to compute the tangent space of a mesh and convert a normal map between world space and tangent space.
Ambient occlusion allows meshes to be visualized properly without any color information. It can also be used for simple de-lighting.

Checklist:

I have run python util/check_style.py --apply to apply Open3D code style
to my code.
This PR changes Open3D behavior or adds new functionality.
- Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
  updated accordingly.
- I have added or updated C++ and / or Python unit tests OR included test
  results (e.g. screenshots or numbers) here.
I will follow up and update the code if CI fails.
For fork PRs, I have selected Allow edits from maintainers.

Description

This PR adds support for tangent space computation and ambient occlusion rendering to triangle meshes. The key changes include implementing MikkTSpace for tangent space calculation, enabling normal map transformations between world and tangent space, and adding ambient occlusion texture generation using ray casting.

Key changes:

Integration of MikkTSpace library for computing tangent space vectors
New methods for ambient occlusion computation and normal map transformation
Addition of quasirandom sequence generation and cross product operations for tensor math

update-docs · 2025-11-07T00:07:06Z

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

Copilot

Pull Request Overview

This PR adds support for tangent space computation and ambient occlusion rendering to triangle meshes. The key changes include implementing MikkTSpace for tangent space calculation, enabling normal map transformations between world and tangent space, and adding ambient occlusion texture generation using ray casting.

Key changes:

Integration of MikkTSpace library for computing tangent space vectors
New methods for ambient occlusion computation and normal map transformation
Addition of quasirandom sequence generation and cross product operations for tensor math
Wayland compatibility fixes for GLFW window positioning

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
cpp/open3d/t/geometry/TriangleMesh.cpp	Implements `ComputeTangentSpace()`, `TransformNormalMap()`, and `ComputeAmbientOcclusion()` methods
cpp/open3d/t/geometry/kernel/mikktspace.h	Adds MikkTSpace library header for tangent space computation
cpp/open3d/t/geometry/kernel/mikktspace.c	Adds MikkTSpace library implementation (1899 lines)
cpp/open3d/core/Tensor.cpp	Implements `Quasirandom()`, `Cross()`, and `Norm()` tensor operations
cpp/tests/t/geometry/TriangleMesh.cpp	Adds comprehensive tests for tangent space and ambient occlusion
cpp/pybind/t/geometry/trianglemesh.cpp	Exposes new mesh methods to Python bindings
cpp/open3d/visualization/visualizer/Visualizer.cpp	Adds Wayland platform checks for window positioning
cpp/open3d/t/io/file_format/FileASSIMP.cpp	Updates texture export to include ambient occlusion maps

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Copilot · 2025-11-07T00:08:35Z

cpp/open3d/core/Tensor.h

+    // https://extremelearning.com.au/unreasonable-effectiveness-of-quasirandom-sequences/
+    // for more details.


The URL reference should be in a Doxygen comment format. These C++ style comments (//) will not appear in generated documentation. Use /// instead for Doxygen comments.

Suggested change

// https://extremelearning.com.au/unreasonable-effectiveness-of-quasirandom-sequences/

// for more details.

/// https://extremelearning.com.au/unreasonable-effectiveness-of-quasirandom-sequences/

/// for more details.

Copilot · 2025-11-07T00:08:35Z

cpp/open3d/core/Tensor.h

    /// t[2, 0:4:2] = np.empty((2, 5), dtype=np.float32)
    /// ```
-    ///
+    ///    Tensor Cross(const Tensor &b) const;


This line appears to be leftover documentation that doesn't belong here. It's placed in the middle of unrelated SetItem documentation and doesn't match the actual Cross() method signature (which takes const Tensor &other and int64_t axis=-1). This should be removed.

Suggested change

/// Tensor Cross(const Tensor &b) const;

Copilot · 2025-11-07T00:08:35Z

cpp/open3d/core/Tensor.h

+    // (i.e. broadcastable) shape, and the size of the specified axis must be 3.
+    // If the axis is -1 (default), the last axis is used.


Inconsistent comment style in Doxygen documentation. Lines 639-640 use // instead of ///. All lines in a Doxygen comment block should use /// for proper documentation generation.

Suggested change

// (i.e. broadcastable) shape, and the size of the specified axis must be 3.

// If the axis is -1 (default), the last axis is used.

/// (i.e. broadcastable) shape, and the size of the specified axis must be 3.

/// If the axis is -1 (default), the last axis is used.

Copilot · 2025-11-07T00:08:36Z

cpp/open3d/core/Tensor.h

+    /// \param p The order of the norm. Default is 2.0 (L2 norm). Can be
+    /// positive infinity (L-infinity norm).
+    /// \return Tensor containing the computed norms. Dtype is
+    /// preserved for Float32 and Float64 for L2 norm, It is onverted to Float32


Corrected spelling of 'converted' from 'onverted'.

Suggested change

/// preserved for Float32 and Float64 for L2 norm, It is onverted to Float32

/// preserved for Float32 and Float64 for L2 norm, It is converted to Float32

Copilot · 2025-11-07T00:08:36Z

cpp/open3d/core/Tensor.cpp

+        utility::LogError(
+                "[Tensor::Cross] Dim axis={} of both tensors must have shape "
+                "3. Got {} and {} instead.",
+                axis, GetShape(3), other.GetShape(3));


Error message uses hardcoded index 3 instead of the axis parameter. Line 1149 should use GetShape(axis) and other.GetShape(axis) to match the actual dimension being checked.

Suggested change

axis, GetShape(3), other.GetShape(3));

axis, GetShape(axis), other.GetShape(axis));

Copilot · 2025-11-07T00:08:36Z

cpp/open3d/visualization/gui/GLFWWindowSystem.cpp

+    // bool visible = !(flags & FLAG_HIDDEN);
+    glfwWindowHint(GLFW_VISIBLE, GLFW_TRUE);


The commented-out code for handling window visibility should either be removed or replaced with a TODO comment explaining why it was disabled. Leaving dead code without explanation reduces maintainability.

Copilot · 2025-11-07T00:08:37Z

cpp/open3d/visualization/gui/GLFWWindowSystem.cpp

+    //if (!visible) {
+    //    glfwHideWindow(glfw_window);
+    //} else {
+    //    glfwShowWindow(glfw_window);
+    //}


Large block of commented-out code without explanation. If this code is no longer needed, it should be removed. If it's kept for reference, add a comment explaining why it's disabled.

Suggested change

//if (!visible) {

// glfwHideWindow(glfw_window);

//} else {

// glfwShowWindow(glfw_window);

//}

ssheorey added 10 commits October 15, 2025 14:51

Wayland does not support setting window position

91d9544

WIP AO compute

38d14ee

WIP

64b412d

Tangent space WIP

a3bab4d

ComputeTangentSpace, ComputeAO, tests, WIP

5b29888

Merge branch 'ss/wayland' into ss/ao

8943416

WIP

4d47151

WIP2 - looks almost correct.

c36164d

WIP

22bfce5

Merge branch 'main' of https://github.com/isl-org/Open3D into ss/ao

2bce57e

ssheorey requested a review from Copilot November 7, 2025 00:07

Copilot AI reviewed Nov 7, 2025

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ssheorey added this to the v0.20 milestone Mar 4, 2026

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Tangent Space and Ambient Occlusion#7364

Tangent Space and Ambient Occlusion#7364
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ssheorey commented Nov 7, 2025 •

edited

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		// https://extremelearning.com.au/unreasonable-effectiveness-of-quasirandom-sequences/
		// for more details.

		// (i.e. broadcastable) shape, and the size of the specified axis must be 3.
		// If the axis is -1 (default), the last axis is used.

	/// preserved for Float32 and Float64 for L2 norm, It is onverted to Float32
	/// preserved for Float32 and Float64 for L2 norm, It is converted to Float32

	axis, GetShape(3), other.GetShape(3));
	axis, GetShape(axis), other.GetShape(axis));

		// bool visible = !(flags & FLAG_HIDDEN);
		glfwWindowHint(GLFW_VISIBLE, GLFW_TRUE);

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Checklist:

Description

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ssheorey commented Nov 7, 2025 •

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