Exporting Data

After registration and deformation, results can be exported to three formats for downstream visualisation and analysis.

Format overview

Format	Extension	Use case
HDF5	`.h5`	Lossless archive of all arrays; re-loadable by the package
VTK	`.vts`	ParaView, DREAM.3D plugin, any VTK-compatible viewer
DREAM.3D	`.dream3d`	DREAM.3D GUI, DREAM.3D ParaView plugin

HDF5

Writes DCT, PCT and DVC data into a single file under logical groups:

/DCT/DS/<key>      — all arrays loaded from the original DCT HDF5
/PCT/vol           — grey-level volume
/PCT/mask          — Otsu binary mask
/DVC/displacement  — (nx, ny, nz, 3) displacement field
/DVC/strain/<key>  — strain fields (if present)
/DVC/origin        — ROI origin in PCT voxel space
/DVC/spacing       — DVC grid spacing

from multimodal_registration import write_h5

write_h5("results.h5", dct=dct, pct=pct, dvc=dvc)

# Or use the dispatcher
from multimodal_registration import write
write("results.h5", dct=dct, pct=pct, dvc=dvc)

VTK

Writes uniform-grid (ImageData) VTK files readable by ParaView and DREAM.3D. When both DCT and DVC are supplied, two files are created automatically: results_dct.vts and results_dvc.vts.

from multimodal_registration import write_vtk

# Both — produces results_dct.vts and results_dvc.vts
write_vtk("results.vts", dct=dct, dvc=dvc)

# DCT only
write_vtk("dct.vts", dct=dct)

# DVC only
write_vtk("dvc.vts", dvc=dvc)

All volumetric arrays in the DCT object (GIDvol, Mask, IPF001, …) are written as point data. DVC displacement and strain fields are written to the DVC file on their own grid (with the correct origin and spacing).

Note

Requires pyvista: pip install "multimodal-registration[vtk]"

DREAM.3D

Produces a DREAM.3D 6.x compatible .dream3d file (HDF5 with a strict internal structure) that can be opened directly in the DREAM.3D application or via the DREAM.3D ParaView plugin.

from multimodal_registration import write_dream3d

write_dream3d("results.dream3d", dct=dct, euler_degrees=True)

What is written

DREAM.3D path	Source	Notes
`CellData/FeatureIds`	`dct.GIDvol`	Grain IDs, 1-based
`CellData/EulerAngles`	`dct.EulerAngle` + `dct.GIDvol`	Per-voxel, radians
`CellData/IPFColors`	`dct.IPF001`	uint8 RGB
`CellData/Mask`	`dct.Mask`	uint8
`CellData/Phases`	constant `phase_id`	Default 1
`CellFeatureData/EulerAngles`	`dct.EulerAngle`	Per-grain, radians
`CellFeatureData/Active`	derived	All grains active
`_SIMPL_GEOMETRY`	`dct.voxel_size`	ImageGeometry

Euler angle convention

DREAM.3D expects Euler angles in radians (Bunge ZXZ). The writer converts from degrees automatically when euler_degrees=True (default).

Opening in ParaView

Open ParaView and load the .dream3d file via File → Open (the DREAM.3D reader is built into ParaView ≥ 5.10).
In the pipeline browser, apply the reader and select which arrays to display (FeatureIds, IPFColors, etc.).
To overlay DVC results, load the _dvc.vts file as a separate source and use a Resample To Image or Probe Location filter to compare on the same grid.

Format dispatcher

write() infers the format from the file extension:

from multimodal_registration import write

write("results.h5",      dct=dct, pct=pct, dvc=dvc)
write("results.vts",     dct=dct, dvc=dvc)
write("results.dream3d", dct=dct)