# MSz: An Efficient Parallel Algorithm for Correcting Morse-Smale Segmentations in Error-Bounded Lossy Compressors
MSZ is designed to preserve topological features such as local minima, maxima, and integral paths with user-defined connectivity modes for 2D/3D datasets. The API supports GPU acceleration (CUDA) and multi-threaded CPU execution (OpenMP).
git clone https://github.com/your-repo/MSz.git
cd MSz
mkdir build && cd build
cmake ..
make -j$(nproc)
make install./MSz_CLI <command> <arguments> --mode <none|omp|cuda>| Command | Description |
|---|---|
count_faults |
Detects false minima, maxima, and incorrect segmentation. |
derive_edits |
Computes topology-preserving edits for decompressed data. |
apply_edits |
Applies topology-preserving edits to decompressed data. |
| Option | Description |
|---|---|
<original_file> |
Path to the original uncompressed data file. |
<decompressed_file> |
Path to the decompressed data file to analyze or modify. |
<edits_file> |
Path to the file containing computed edits (required for apply_edits). |
<width> |
Width (x-dimension) of the dataset. |
<height> |
Height (y-dimension) of the dataset. |
<depth> |
Depth (z-dimension) of the dataset (set to 1 for 2D data). |
<connectivity> |
Connectivity type:0 - Piecewise connectivity (e.g., 2D: up, down, left, right, upper-right, lower-left)1 - Full connectivity (e.g., 2D: includes diagonals). |
<error_bound> |
Floating-point value specifying the error bound (e.g., 1E-3, 0.01) [Only for derive_edits]. |
<preserve_min> |
Preserve minima (1 = Yes, 0 = No) [Only for derive_edits]. |
<preserve_max> |
Preserve maxima (1 = Yes, 0 = No) [Only for derive_edits]. |
<preserve_path> |
Preserve separatrices (1 = Yes, 0 = No) [Only for derive_edits and connectivity == 0]. |
--mode <exec_mode> |
Execution mode:none - Pure CPU execution omp - OpenMP parallel execution cuda - GPU acceleration using CUDA |
./MSz_CLI count_faults original.bin decompressed.bin 100 100 100 0 --mode cudaExpected Output:
Using CUDA execution.
Count faults succeeded.
False minima: x
False maxima: x
False labels: x./MSz_CLI derive_edits original.bin decompressed.bin 100 100 100 0 1E-3 1 1 1 --mode ompExpected Output:
Using OpenMP execution.
Derive edits succeeded. Number of edits: 35
Edits saved to edits.bin./MSz_CLI apply_edits decompressed.bin edits.bin 100 100 100 --mode cudaExpected Output:
Using CUDA execution.
Apply edits succeeded.
Edited data saved to edited_data.binint MSz_derive_edits(
const double *original_data, // Input: original data array
const double *decompressed_data, // Input: decompressed data array
double *edited_decompressed_data, // Output: edited data array (optional, can be nullptr)
int &num_edits, // Output: number of edits
MSz_edit_t **edits, // Output: array of computed edits
unsigned int preservation_options, // Bitset for preservation options
unsigned int connectivity_type, // Connectivity type specifier (0 = piecewise, 1 = full connectivity)
int W, int H, int D, // Dimensions of the data (width, height, depth)
double rel_err_bound, // Relative error bound for edits
int accelerator = MSZ_ACCELERATOR_CUDA, // Hardware accelerator
int device_id = 0, // GPU device ID (used if accelerator is CUDA)
int num_omp_threads = 1 // Number of threads (used if accelerator is OMP)
);int MSz_derive_edits(
const double *original_data, // Input: original data array
const double *decompressed_data, // Input: decompressed data array
double *edited_decompressed_data, // Output: edited data array (optional, can be nullptr)
int &num_edits, // Output: number of edits
MSz_edit_t **edits, // Output: array of computed edits
unsigned int preservation_options, // Bitset for preservation options
unsigned int connectivity_type, // Connectivity type specifier (0 = piecewise, 1 = full connectivity)
int W, int H, int D, // Dimensions of the data (width, height, depth)
double rel_err_bound, // Relative error bound for edits
int accelerator = MSZ_ACCELERATOR_CUDA, // Hardware accelerator
int device_id = 0, // GPU device ID (used if accelerator is CUDA)
int num_omp_threads = 1 // Number of threads (used if accelerator is OMP)
);Description:
Computes the necessary edits to preserve critical topological features while keeping decompressed data within the given error bound.
int MSz_count_faults(
const double *original_data, // Input: original data array
const double *decompressed_data, // Input: decompressed data array
int &num_false_min, // Output: number of false minima
int &num_false_max, // Output: number of false maxima
int &num_false_labels, // Output: number of mislabeled points
unsigned int connectivity_type, // Connectivity type specifier
int W, int H, int D, // Dimensions of the data
int accelerator = MSZ_ACCELERATOR_CUDA, // Hardware accelerator
int device_id = 0, // GPU device ID (used if accelerator is CUDA)
int num_omp_threads = 1 // Number of threads (used if accelerator is OMP)
);Description:
Detects false minima, maxima, and incorrect segmentation in decompressed data.
int MSz_apply_edits( // return MSZ_ERR_NO_ERROR if success
double *decompressed_data, // Input/Output: decompressed data to be modified
int num_edits, // Input: number of edits to apply
const MSz_edit_t *edits, // Input: array of edits
int W, int H, int D, // Input: dimensions of the data
int accelerator = MSZ_ACCELERATOR_NONE, // Input: hardware accelerator
int device_id = 0, // Input: GPU device ID (if using CUDA)
int num_omp_threads = 1 // Input: number of threads (if using OpenMP)
);Description:
Applies computed topology-preserving edits to modify decompressed data.
int MSz_compress_edits_zstd( // return MSZ_ERR_NO_ERROR if success
int num_edits, // Number of edits
MSz_edit_t *edits, // Input: Array of edits
char **compressed_buffer, // Output: compressed buffer
size_t &compressed_size // Output: size of compressed buffer
);Description:
Losslessly compresses edit data using Zstandard (Zstd) to reduce storage and transmission overhead.
int MSz_decompress_edits_zstd( // return MSZ_ERR_NO_ERROR if success
const char *compressed_buffer, // Input: pointer to the compressed buffer
size_t compressed_size, // Input: size of the compressed buffer (in bytes)
int &num_edits, // Output: number of decompressed edits
MSz_edit_t **edits // Output: pointer to an array of decompressed edits
);Description:
Restores topology-preserving edits from a Zstd-compressed buffer.
- Multi-threading support (OpenMP)
- GPU acceleration (CUDA)
For questions or contributions, please reach out via [li.14025@osu.edu].