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d91d602
ENH: Add out-of-core (OOC) storage architecture for simplnx
joeykleingers Jun 1, 2026
8d4a2a7
REFACTOR: Rename algorithm files for OOC dispatch preparation
joeykleingers Mar 31, 2026
949ac59
PERF: Out-of-core (OOC) optimized algorithms for SimplnxCore and Orie…
joeykleingers Apr 8, 2026
4fc37a2
FIX: Resolve OOC store format in tests and fix ComputeAvgOrientations…
joeykleingers Apr 14, 2026
7787a64
DOCS: Add comprehensive Doxygen and inline documentation for OOC-opti…
joeykleingers Apr 14, 2026
750dbec
COMP: Fix compile error in Windows
imikejackson Apr 17, 2026
14f850a
PERF: OOC-optimize WritePoleFigure per-element input reads and image …
joeykleingers Apr 20, 2026
87ce9eb
TEST: Register exemplar archives for OOC-optimized filter tests
joeykleingers Apr 21, 2026
424e380
PERF: Optimize CropImageGeometry with Z-slab batching for OOC
joeykleingers Apr 22, 2026
c3d6a3a
PERF: Optimize RequireMinimumSizeFeatures memory and I/O patterns
joeykleingers Apr 22, 2026
b1b9b16
PERF: Optimize ExtractInternalSurfacesFromTriangleGeometry for OOC
joeykleingers Apr 22, 2026
0ebc084
PERF: Optimize ApplyTransformationToGeometry for out-of-core data
joeykleingers Apr 22, 2026
79e1aa5
PERF: Optimize ComputeTriangleAreas with chunked bulk vertex loads
joeykleingers Apr 22, 2026
4a63661
PERF: Increase ComputeFeatureSizes chunk size for multi-billion-voxel…
joeykleingers Apr 22, 2026
08c4c44
DOC: Expand CropImageGeometry algorithm documentation
joeykleingers Apr 22, 2026
f24042b
DOC: Expand RequireMinimumSizeFeatures algorithm documentation
joeykleingers Apr 22, 2026
4a9cc5a
DOC: Add ExtractInternalSurfacesFromTriangleGeometry algorithm section
joeykleingers Apr 22, 2026
d14e769
DOC: Add ApplyTransformationToGeometry algorithm section
joeykleingers Apr 22, 2026
7778817
DOC: Add ComputeTriangleAreas algorithm section
joeykleingers Apr 22, 2026
57c9b12
DOC: Expand ComputeFeatureSizes algorithm documentation
joeykleingers Apr 22, 2026
906e414
BUG: Use double-precision Pi/180 in ComputeGBCDMetricBased
joeykleingers Apr 23, 2026
f887332
ENH: Apply PR #1590 to OOC dispatch variants and fix bool-mask bulk I/O
joeykleingers Apr 27, 2026
9b25317
ENH: Unify CreateDataStore and CreateListStore through format resolver
joeykleingers Apr 29, 2026
491c1f8
ENH: Register OOC format from DataIOCollection ctor; fix in-core Data…
joeykleingers May 29, 2026
37aab6a
PERF: Split ComputeFeatureSizes into in-core and out-of-core variants
joeykleingers Jun 5, 2026
8ffaea0
COMP: Honor SIMPLNX_TEST_ALGORITHM_PATH=Both in in-core builds
joeykleingers Jun 5, 2026
4f031e2
BUG: Honor compression in the OOC streaming write path
joeykleingers Jun 5, 2026
bb687c7
TEST: Assert recovery store type from preferences, not hardcoded in-core
joeykleingers Jun 5, 2026
4e86efc
ENH: Machine-aware memory budget cap in MemoryBudgetManager
jmarquisbq Jun 5, 2026
db71378
REFACTOR: decouple out-of-core from core via runtime resolver + IO hooks
joeykleingers Jun 8, 2026
a486b90
ENH: Memory-safety defensive programming (preflight -271 warning + ba…
jmarquisbq Jun 8, 2026
c3cc4bc
FIX: Add /bigobj to the simplnx MSVC build for Dream3dIO.cpp
jmarquisbq Jun 9, 2026
1cbfa4c
REFACTOR: Name the built-in data-store-format display labels
jmarquisbq Jun 9, 2026
31420ba
COMP: List two unlisted headers and group unit-test sources for the IDE
jmarquisbq Jun 9, 2026
c1f0dfd
COMP: add zlib as a direct simplnx vcpkg dependency
joeykleingers Jun 9, 2026
f6d49e9
ENH: Record plugin unit-test targets on a global property
joeykleingers Jun 10, 2026
9db0dde
PERF: Optimize ComputeFeaturePhases for out-of-core data
joeykleingers Jun 10, 2026
eff8b87
Fix data archive hashes
jmarquisbq Jun 11, 2026
0763345
Revert "Fix data archive hashes"
joeykleingers Jun 11, 2026
3c8903e
REV: Integrate EbsdLib 3.0.0 V&V changes with OOC branch APIs post-re…
joeykleingers Jun 12, 2026
d81c239
BUG: Clamp default memory budget to the machine cap on low-RAM systems
joeykleingers Jun 12, 2026
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27 changes: 27 additions & 0 deletions CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,14 @@ option(SIMPLNX_DOWNLOAD_TEST_FILES "Download the test files" ON)
# ------------------------------------------------------------------------------
option(SIMPLNX_WRITE_TEST_OUTPUT "Write unit test output files" OFF)

# ------------------------------------------------------------------------------
# Controls which algorithm paths are exercised by dual-dispatch unit tests.
# 0 (Both) - tests run with forceOoc=false AND forceOoc=true (default)
# 1 (OocOnly) - tests run with forceOoc=true only (use for OOC builds)
# 2 (InCoreOnly) - tests run with forceOoc=false only (quick validation)
# ------------------------------------------------------------------------------
set(SIMPLNX_TEST_ALGORITHM_PATH "0" CACHE STRING "Algorithm paths to test: 0=Both, 1=OocOnly, 2=InCoreOnly")

# ------------------------------------------------------------------------------
# Is the SimplnxCore Plugin enabled [DEFAULT=ON]
# ------------------------------------------------------------------------------
Expand Down Expand Up @@ -245,6 +253,9 @@ if(MSVC)
target_compile_options(simplnx
PRIVATE
/MP
# Dream3dIO.cpp exceeds the default COMDAT section limit (C1128) in Debug
# after the out-of-core resolver refactor; /bigobj raises the limit.
/bigobj
)
endif()

Expand All @@ -261,6 +272,7 @@ if(SIMPLNX_ENABLE_MULTICORE)
target_link_libraries(simplnx PUBLIC TBB::tbb)
endif()


target_link_libraries(simplnx
PUBLIC
fmt::fmt
Expand Down Expand Up @@ -293,6 +305,11 @@ if(SIMPLNX_ENABLE_LINK_FILESYSTEM)
endif()

set(SIMPLNX_GENERATED_DIR ${simplnx_BINARY_DIR}/generated)

configure_file(
${simplnx_SOURCE_DIR}/cmake/SimplnxConfig.hpp.in
${SIMPLNX_GENERATED_DIR}/simplnx/Common/SimplnxConfig.hpp
@ONLY)
set(SIMPLNX_GENERATED_HEADER_DIR ${simplnx_BINARY_DIR}/generated/simplnx)
set(SIMPLNX_EXPORT_HEADER ${SIMPLNX_GENERATED_HEADER_DIR}/simplnx_export.hpp)

Expand Down Expand Up @@ -351,6 +368,7 @@ set(SIMPLNX_HDRS
${SIMPLNX_SOURCE_DIR}/Common/Constants.hpp
${SIMPLNX_SOURCE_DIR}/Common/DataTypeUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Common/DataVector.hpp
${SIMPLNX_SOURCE_DIR}/Common/Extent.hpp
${SIMPLNX_SOURCE_DIR}/Common/EulerAngle.hpp
${SIMPLNX_SOURCE_DIR}/Common/Filesystem.hpp
${SIMPLNX_SOURCE_DIR}/Common/IteratorUtility.hpp
Expand Down Expand Up @@ -380,6 +398,8 @@ set(SIMPLNX_HDRS
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/DataIOCollection.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/IDataFactory.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/IDataIOManager.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/IDataStoreFormatResolver.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/InMemoryFormatResolver.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/IOConstants.hpp

${SIMPLNX_SOURCE_DIR}/DataStructure/IO/HDF5/DataIOManager.hpp
Expand Down Expand Up @@ -465,6 +485,7 @@ set(SIMPLNX_HDRS
${SIMPLNX_SOURCE_DIR}/DataStructure/DynamicListArray.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/EmptyDataStore.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/EmptyListStore.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/EmptyStringStore.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IArray.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IDataArray.hpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IDataStore.hpp
Expand Down Expand Up @@ -540,12 +561,14 @@ set(SIMPLNX_HDRS
${SIMPLNX_SOURCE_DIR}/Plugin/PluginLoader.hpp

${SIMPLNX_SOURCE_DIR}/Utilities/ArrayCreationUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/SliceBufferedTransfer.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/AlignSections.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/ArrayThreshold.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/DataArrayUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/DataGroupUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/DataObjectUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/DataStoreUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/AlgorithmDispatch.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/FilePathGenerator.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/ColorTableUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/FileUtilities.hpp
Expand All @@ -556,6 +579,7 @@ set(SIMPLNX_HDRS
${SIMPLNX_SOURCE_DIR}/Utilities/HistogramUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/MaskCompareUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/MemoryUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/MemoryBudgetManager.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/MessageHelper.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/StringUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/StringInterpretationUtilities.hpp
Expand All @@ -568,6 +592,7 @@ set(SIMPLNX_HDRS
${SIMPLNX_SOURCE_DIR}/Utilities/SamplingUtils.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/SegmentFeatures.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/TimeUtilities.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/UnionFind.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/TooltipGenerator.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/TooltipRowItem.hpp
${SIMPLNX_SOURCE_DIR}/Utilities/OStreamUtilities.hpp
Expand Down Expand Up @@ -639,6 +664,7 @@ set(SIMPLNX_SRCS

${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/DataIOCollection.cpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/IDataIOManager.cpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/IDataStoreFormatResolver.cpp
${SIMPLNX_SOURCE_DIR}/DataStructure/IO/Generic/CoreDataIOManager.cpp

${SIMPLNX_SOURCE_DIR}/DataStructure/IO/HDF5/DataIOManager.cpp
Expand Down Expand Up @@ -770,6 +796,7 @@ set(SIMPLNX_SRCS
${SIMPLNX_SOURCE_DIR}/Utilities/DataStoreUtilities.cpp
${SIMPLNX_SOURCE_DIR}/Utilities/MaskCompareUtilities.cpp
${SIMPLNX_SOURCE_DIR}/Utilities/MemoryUtilities.cpp
${SIMPLNX_SOURCE_DIR}/Utilities/MemoryBudgetManager.cpp
${SIMPLNX_SOURCE_DIR}/Utilities/MessageHelper.cpp
${SIMPLNX_SOURCE_DIR}/Utilities/IParallelAlgorithm.cpp
${SIMPLNX_SOURCE_DIR}/Utilities/ParallelDataAlgorithm.cpp
Expand Down
6 changes: 6 additions & 0 deletions cmake/Plugin.cmake
Original file line number Diff line number Diff line change
Expand Up @@ -355,6 +355,11 @@ function(create_simplnx_plugin_unit_test)
${${ARGS_PLUGIN_NAME}UnitTest_SRCS}
)

# Record every plugin unit-test target on a global property so consumer builds
# (which include simplnx via add_subdirectory) can attach additional sources or
# settings to the test executables without simplnx knowing about the consumer.
set_property(GLOBAL APPEND PROPERTY SIMPLNX_UNIT_TEST_TARGETS ${UNIT_TEST_TARGET})

target_link_libraries(${UNIT_TEST_TARGET}
PRIVATE
simplnx
Expand Down Expand Up @@ -389,6 +394,7 @@ function(create_simplnx_plugin_unit_test)
target_compile_definitions(${UNIT_TEST_TARGET}
PRIVATE
SIMPLNX_BUILD_DIR="$<TARGET_FILE_DIR:simplnx_test>"
SIMPLNX_TEST_ALGORITHM_PATH=${SIMPLNX_TEST_ALGORITHM_PATH}
)

target_compile_options(${UNIT_TEST_TARGET}
Expand Down
12 changes: 12 additions & 0 deletions cmake/SimplnxConfig.hpp.in
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
#pragma once

// This header is generated from cmake/SimplnxConfig.hpp.in by configure_file().
// It carries compile-time configuration into every translation unit that links
// simplnx, including MOC, via simplnx's PUBLIC generated include directory.
// Delivering values through a header (not per-target compile definitions) keeps
// them identical across all consumers, which is required for ODR safety when a
// macro gates inline code in public headers.
//
// Out-of-core support is no longer a compile-time switch in core simplnx; OOC is
// provided at runtime by a registered IO manager (see DataIOCollection). This
// header is retained for future compile-time configuration values.
Original file line number Diff line number Diff line change
Expand Up @@ -840,7 +840,7 @@ Result<OutputActions> DataCheck(const DataStructure& dataStructure, const DataPa
const auto& inputArray = dataStructure.getDataRefAs<IDataArray>(inputArrayPath);
const auto& inputDataStore = inputArray.getIDataStoreRef();

if(!inputArray.getDataFormat().empty())
if(inputArray.getStoreType() == IDataStore::StoreType::OutOfCore)
{
return MakeErrorResult<OutputActions>(Constants::k_OutOfCoreDataNotSupported,
fmt::format("Input Array '{}' utilizes out-of-core data. This is not supported within ITK filters.", inputArrayPath.toString()));
Expand All @@ -862,7 +862,7 @@ Result<detail::ITKFilterFunctorResult_t<FilterCreationFunctorT>> Execute(DataStr

using ResultT = detail::ITKFilterFunctorResult_t<FilterCreationFunctorT>;

if(!inputArray.getDataFormat().empty())
if(inputArray.getStoreType() == IDataStore::StoreType::OutOfCore)
{
return MakeErrorResult(Constants::k_OutOfCoreDataNotSupported, fmt::format("Input Array '{}' utilizes out-of-core data. This is not supported within ITK filters.", inputArrayPath.toString()));
}
Expand Down
44 changes: 2 additions & 42 deletions src/Plugins/ITKImageProcessing/test/ITKTestBase.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ std::string ComputeMD5HashTyped(const IDataArray& outputDataArray)
usize arraySize = dataArray.getSize();

MD5 md5;
if(outputDataArray.getDataFormat().empty())
if(outputDataArray.getIDataStoreRef().getStoreType() != IDataStore::StoreType::OutOfCore)
{
const T* dataPtr = dataArray.template getIDataStoreRefAs<DataStore<T>>().data();
md5.update(reinterpret_cast<const uint8*>(dataPtr), arraySize * sizeof(T));
Expand Down Expand Up @@ -135,47 +135,7 @@ namespace ITKTestBase
bool IsArrayInMemory(DataStructure& dataStructure, const DataPath& outputDataPath)
{
const auto& outputDataArray = dataStructure.getDataRefAs<IDataArray>(outputDataPath);
DataType outputDataType = outputDataArray.getDataType();

switch(outputDataType)
{
case DataType::float32: {
return dynamic_cast<const DataArray<float32>&>(outputDataArray).getDataFormat().empty();
}
case DataType::float64: {
return dynamic_cast<const DataArray<float64>&>(outputDataArray).getDataFormat().empty();
}
case DataType::int8: {
return dynamic_cast<const DataArray<int8>&>(outputDataArray).getDataFormat().empty();
}
case DataType::uint8: {
return dynamic_cast<const DataArray<uint8>&>(outputDataArray).getDataFormat().empty();
}
case DataType::int16: {
return dynamic_cast<const DataArray<int16>&>(outputDataArray).getDataFormat().empty();
}
case DataType::uint16: {
return dynamic_cast<const DataArray<uint16>&>(outputDataArray).getDataFormat().empty();
}
case DataType::int32: {
return dynamic_cast<const DataArray<int32>&>(outputDataArray).getDataFormat().empty();
}
case DataType::uint32: {
return dynamic_cast<const DataArray<uint32>&>(outputDataArray).getDataFormat().empty();
}
case DataType::int64: {
return dynamic_cast<const DataArray<int64>&>(outputDataArray).getDataFormat().empty();
}
case DataType::uint64: {
return dynamic_cast<const DataArray<uint64>&>(outputDataArray).getDataFormat().empty();
}
case DataType::boolean: {
[[fallthrough]];
}
default: {
return {};
}
}
return outputDataArray.getIDataStoreRef().getStoreType() != IDataStore::StoreType::OutOfCore;
}
//------------------------------------------------------------------------------
std::string ComputeMd5Hash(DataStructure& dataStructure, const DataPath& outputDataPath)
Expand Down
7 changes: 6 additions & 1 deletion src/Plugins/OrientationAnalysis/CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,8 @@ set(filter_algorithms
AlignSectionsMisorientation
AlignSectionsMutualInformation
BadDataNeighborOrientationCheck
BadDataNeighborOrientationCheckScanline
BadDataNeighborOrientationCheckWorklist
CAxisSegmentFeatures
ComputeAvgCAxes
ComputeAvgOrientations
Expand All @@ -186,9 +188,12 @@ set(filter_algorithms
ComputeFZQuaternions
ComputeGBCD
ComputeGBCDMetricBased
ComputeGBCDPoleFigure
ComputeGBCDPoleFigureDirect
ComputeGBCDPoleFigureScanline
ComputeGBPDMetricBased
ComputeIPFColors
ComputeIPFColorsDirect
ComputeIPFColorsScanline
ComputeKernelAvgMisorientations
ComputeMisorientations
ComputeQuaternionConjugate
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,20 @@ In this new structure, what follows is what the created structures represent:
In previous versions a file would have been produced instead. If you wish to recreate this, you can write the Attribute Matrix as a CSV/Text file.


## Algorithm

### In-Core Path

For each pair of adjacent Z-sections, the algorithm computes the misorientation between voxels across the section boundary. It tests candidate X-Y shifts to find the shift that minimizes the total misorientation between the two sections. All voxel comparisons use direct array indexing with `operator[]`.

### Out-of-Core Path

Reads pairs of adjacent Z-slices into local memory buffers using `copyIntoBuffer()`. All misorientation comparisons for a given slice pair operate entirely on the in-memory buffers. This converts what would otherwise be random cross-slice element access into sequential bulk reads, avoiding chunk thrashing when data is stored on disk in compressed chunks.

### Performance

The OOC optimization matters most for large datasets that exceed available RAM. By reading entire Z-slices in bulk rather than accessing individual voxels across slice boundaries, the algorithm avoids repeatedly decompressing the same disk chunks. For in-memory datasets, the two paths produce identical results with negligible overhead difference.

% Auto generated parameter table will be inserted here

## Example Pipelines
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,20 @@ In this new structure, what follows is what the created structures represent:

In previous versions a file would have been produced instead. If you wish to recreate this, you can write the Attribute Matrix as a CSV/Text file.

## Algorithm

### In-Core Path

Aligns Z-sections by maximizing the mutual information of orientation data between adjacent slices. The algorithm segments each slice into temporary features, bins the orientations, and computes joint and marginal histograms to evaluate mutual information at each candidate shift position. All orientation and feature ID data is accessed through direct array indexing with `operator[]`.

### Out-of-Core Path

Reads the orientation and phase data for each pair of adjacent Z-slices into local memory buffers using `copyIntoBuffer()` before computing histograms. This eliminates per-voxel out-of-core reads during the histogram binning and mutual information calculation, replacing them with two sequential bulk reads per slice pair.

### Performance

The OOC optimization matters most for large datasets that exceed available RAM. Histogram computation requires visiting every voxel in both slices multiple times (once per candidate shift), so eliminating per-element OOC access prevents repeated decompression of the same disk chunks. For in-memory datasets, the two paths produce identical results with negligible overhead difference.

% Auto generated parameter table will be inserted here

## References
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,32 @@ The filter allocates a temporary `int32` neighbor-count array sized to the total
(4 bytes per voxel). For a 1-billion-voxel dataset, that is approximately 4 GB of additional
working memory during execution. This memory is released when the filter finishes.

### Implementation Notes

The filter selects between two implementations at runtime based on how the input arrays are stored.

#### In-Core Path (BadDataNeighborOrientationCheckWorklist)

When all arrays reside in contiguous in-memory storage, the algorithm uses a two-phase worklist approach:

1. **Phase 1 (Initial count)**: A single linear scan counts matching good face-neighbors for every bad voxel, storing the count in a per-voxel array (the neighbor-count array described under *Memory Considerations*).
2. **Phase 2 (Worklist propagation)**: For each level, a deque is seeded with all bad voxels meeting the threshold. As each voxel is flipped, its still-bad neighbors' counts are incremented. If a neighbor's count now meets the threshold, it is enqueued. This breadth-first flood-fill processes each voxel at most once per level, achieving O(flipped) amortized cost.

#### Out-of-Core Path (BadDataNeighborOrientationCheckScanline)

When any of the quaternion, mask, or phase arrays are backed by chunked (OOC) disk storage, the algorithm uses a 3-slice rolling window over the Z axis:

1. Three Z-slices of quaternions, phases, and mask data are maintained in memory (previous, current, next).
2. For each bad voxel in the current slice, the count of matching good face-neighbors is recomputed on-the-fly using the rolling window buffers.
3. If a voxel is flipped, the mask change is written back to the OOC store per-slice via `copyFromBuffer()`.
4. The window shifts forward one Z-slice at a time, with only one new slice loaded per step.

This approach trades recomputation (no persistent neighbor-count array) for strictly sequential I/O that avoids the random-access chunk thrashing that would occur with the worklist variant's BFS pattern.

#### Performance

The in-core worklist variant is significantly faster for datasets that fit in RAM because each voxel is processed at most once per level (O(flipped) cost vs. O(N * passes) for the scanline variant). The OOC scanline variant is slower in absolute terms but avoids catastrophic performance degradation on disk-backed datasets where the worklist's random access pattern would trigger continuous chunk load/evict cycles. Memory usage is O(N) for the worklist variant vs. O(3 * sliceSize) for the scanline variant.

## Example Data

| Example Input Image | Example Output Image |
Expand Down
16 changes: 16 additions & 0 deletions src/Plugins/OrientationAnalysis/docs/CAxisSegmentFeaturesFilter.md
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,22 @@ is to still use the 6 face neighbors ("Face Only") in order to stay consistent w
|:--:|:--:|
| ![Shared Edges & Points With Disconnected Region - "Face Only"](Images/SegmentFeatures/combination_face_only.png) | ![Shared Edges & Points With Disconnected Region - "All Connected"](Images/SegmentFeatures/combination_all_connected.png) |

## Algorithm

This filter segments voxels into features based on c-axis alignment, targeting hexagonal crystal systems. Voxels whose c-axes (the <001> crystallographic direction) are aligned within a user-defined tolerance are grouped into the same feature.

### In-Core Path

Uses a BFS-style flood fill where seed voxels are compared to their neighbors by computing the c-axis misalignment via direct array access with `operator[]`. Neighbors within tolerance are added to the current feature and queued for further expansion.

### Out-of-Core Path

Adapted to use sequential data access through the `SegmentFeatures` base class OOC support. The base class manages bulk I/O so that the flood-fill algorithm can proceed without triggering per-voxel OOC reads across chunk boundaries.

### Performance

The OOC optimization matters most for large datasets that exceed available RAM. Flood-fill naturally exhibits random access patterns as it grows regions across Z-slices, which can cause severe chunk thrashing with compressed on-disk storage. The OOC path mitigates this by leveraging the base class sequential access strategy. For in-memory datasets, the two paths produce identical results with negligible overhead difference.

% Auto generated parameter table will be inserted here

## Example Pipelines
Expand Down
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