Improve Documentation - Fix code links and improve tutorial layout (#6321)

* Correct code tagging in interactive_visualization tutorial.

* Highlight the methods that are being introduced at the start.

* Non-Blocking VIZ - Add add_geometry step which is not optional.

* Non-Blocking VIZ - Split main code to simpler function and fix code blocks in docs.

* Fix Typos

* Update docs with new argument values.

* Fix grammar and dedent for overly indented code

* Integrate_Custom - Optimize imports, add early return, use f-strings and remove unnecessary parentheses.

* Fix default value and remove BooleanOptionalAction, its only available >= python 3.9

* Disable use of cuda for tensor based reconstruction

* Customized Integration - Fix code lines

* Ray Casting - Fix code lines

* Dense Slam - Fix code lines and slight grammar.

* Fix some f-strings and extra parantheses

* Make Fragments - Fix code lines

* Code for batch processing was removed long back in #521 in 2018

* Register Fragments - Fix code docs

* Register fragments - Fix code lines

* Integrate Scene - Fix code lines

* Change layout of tutorials - only done at top level.

* Add new lines before bullet/numbered list, else list rendering fails.

* Bugfix - Fix code lines for Integration and add filename as done in v0.14.0

* Remove python version 3.6 as supported versions by open3d.

* Fix line number using lineno-match directive.

* Fix some typos detected automatically.

* Replace prepend with lineno-match

* Correct filename documented in the files

* Fix lineno-start.

* Fix PR comments

* Revert "Code for batch processing was removed long back in #521 in 2018"

This reverts commit d65fb67.

* Correct batch processing section documentation and native multiprocessing.

* Use native multiprocessing for register fragments and refinement of registration

---------

Co-authored-by: Sameer Sheorey <[email protected]>

Author: saurabheights

README.md

@@ -45,7 +45,7 @@ For more, please visit the [Open3D documentation](http://www.open3d.org/docs).
 ## Python quick start
 
 Pre-built pip packages support Ubuntu 18.04+, macOS 10.15+ and Windows 10+
-(64-bit) with Python 3.6-3.10.
+(64-bit) with Python 3.7-3.10.
 
 ```bash
 # Install

cpp/open3d/core/AdvancedIndexing.cpp

@@ -206,7 +206,7 @@ void AdvancedIndexPreprocessor::RunPreprocess() {
     // If the indexed_shape_ contains a dimension of size 0 but the
     // replacement shape does not, the index is out of bounds. This is because
     // there is no valid number to index an empty tensor.
-    // Normally, out of bounds is detected in the advanded indexing kernel. We
+    // Normally, out of bounds is detected in the advanced indexing kernel. We
     // detected here for more helpful error message.
     auto contains_zero = [](const SizeVector& vals) -> bool {
         return std::any_of(vals.begin(), vals.end(),

cpp/open3d/core/AdvancedIndexing.h

@@ -49,7 +49,7 @@ class AdvancedIndexPreprocessor {
             const Tensor& tensor, const std::vector<Tensor>& index_tensors);
 
     /// Expand all tensors to the broadcasted shape, 0-dim tensors are ignored.
-    /// Thorws exception if the common broadcasted shape does not exist.
+    /// Throws exception if the common broadcasted shape does not exist.
     static std::pair<std::vector<Tensor>, SizeVector>
     ExpandToCommonShapeExceptZeroDim(const std::vector<Tensor>& index_tensors);
 
@@ -127,7 +127,7 @@ class AdvancedIndexer {
         if (indexed_shape.size() != indexed_strides.size()) {
             utility::LogError(
                     "Internal error: indexed_shape's ndim {} does not equal to "
-                    "indexd_strides' ndim {}",
+                    "indexed_strides' ndim {}",
                     indexed_shape.size(), indexed_strides.size());
         }
         num_indices_ = indexed_shape.size();

cpp/open3d/geometry/BoundingVolume.h

@@ -21,7 +21,7 @@ class AxisAlignedBoundingBox;
 /// \brief A bounding box oriented along an arbitrary frame of reference.
 ///
 /// The oriented bounding box is defined by its center position, rotation
-/// maxtrix and extent.
+/// matrix and extent.
 class OrientedBoundingBox : public Geometry3D {
 public:
     /// \brief Default constructor.

cpp/open3d/geometry/VoxelGrid.h

@@ -245,7 +245,7 @@ class VoxelGrid : public Geometry3D {
 public:
     /// Size of the voxel.
     double voxel_size_ = 0.0;
-    /// Coorindate of the origin point.
+    /// Coordinate of the origin point.
     Eigen::Vector3d origin_ = Eigen::Vector3d::Zero();
     /// Voxels contained in voxel grid
     std::unordered_map<Eigen::Vector3i,

cpp/open3d/ml/impl/continuous_conv/ContinuousConvBackpropFilter.cuh

@@ -45,7 +45,7 @@ namespace impl {
 /// \param texture_alignment    The texture alignment in bytes. This is used
 ///        for allocating segments within the temporary memory.
 ///
-/// \param filter_backrop    Output array for the computed filter gradient
+/// \param filter_backprop    Output array for the computed filter gradient
 ///        with shape [depth,height,width, inp channels, out channels]
 ///
 /// \param filter_dims    The sizes of the filter dimensions. The size of

cpp/open3d/ml/tensorflow/misc/BuildSpatialHashTableOps.cpp

@@ -78,7 +78,7 @@ The following example shows how **build_spatial_hash_table** and
 
   radius = 1.0
 
-  # build the spatial hash table for fixex_radius_search
+  # build the spatial hash table for fixed_radius_search
   table = ml3d.ops.build_spatial_hash_table(points,
                                             radius,
                                             points_row_splits=torch.LongTensor([0,5]),

cpp/open3d/t/geometry/BoundingVolume.cpp

@@ -318,7 +318,7 @@ OrientedBoundingBox::OrientedBoundingBox(const core::Tensor &center,
         utility::LogError(
                 "Invalid oriented bounding box. Please make sure the values of "
                 "extent are all positive and the rotation matrix is "
-                "othogonal.");
+                "orthogonal.");
     }
 }
 

cpp/open3d/t/geometry/BoundingVolume.h

@@ -146,7 +146,7 @@ class AxisAlignedBoundingBox : public Geometry, public DrawableGeometry {
             const utility::optional<core::Tensor> &center = utility::nullopt);
 
     /// \brief Add operation for axis-aligned bounding box.
-    /// The device of ohter box must be the same as the device of the current
+    /// The device of other box must be the same as the device of the current
     /// box.
     AxisAlignedBoundingBox &operator+=(const AxisAlignedBoundingBox &other);
 
@@ -223,7 +223,7 @@ class AxisAlignedBoundingBox : public Geometry, public DrawableGeometry {
 /// \brief A bounding box oriented along an arbitrary frame of reference.
 ///
 /// - (center, rotation, extent): The oriented bounding box is defined by its
-/// center position, rotation maxtrix and extent.
+/// center position, rotation matrix and extent.
 ///     - Usage
 ///         - OrientedBoundingBox::GetCenter()
 ///         - OrientedBoundingBox::SetCenter(const core::Tensor &center)

cpp/open3d/visualization/gui/Window.cpp

@@ -707,7 +707,7 @@ Widget::DrawResult DrawChild(DrawContext& dc,
                              const char* name,
                              std::shared_ptr<Widget> child,
                              Mode mode) {
-    // Note: ImGUI's concept of a "window" is really a moveable child of the
+    // Note: ImGUI's concept of a "window" is really a movable child of the
     //       OS window. We want a child to act like a child of the OS window,
     //       like native UI toolkits, Qt, etc. So the top-level widgets of
     //       a window are drawn using ImGui windows whose frame is specified