flimkit-zstack-explorer

3D intensity and FLIM volume explorer for FLIMKit z-stacks. Takes a z-stack you've already loaded or fitted in FLIMKit, stacks its per-slice intensity and lifetime maps into (Z, Y, X) volumes, saves them as an OME-Zarr store, and opens a popout 3D viewer with the two volumes side by side.

What it does

• Adds Tools > 3D Z-stack Explorer... to FLIMKit.
• Only does anything once a z-stack is loaded (FOV mode > Z-stack); otherwise it tells you to load one first.
• Walks every slice in the loaded z-stack through the FOV preview panel's own display code (the same path used when you drag the z-slider), so the volume matches what's on screen slice by slice.
• Saves a 2-channel OME-Zarr store (channel 0 = intensity, channel 1 = lifetime in ns, NaN where a slice had no per-pixel fit). Saving to a path that already has a store from a previous run overwrites it.
• Opens a PyVista point-cloud viewer in its own process — intensity on the left, FLIM lifetime on the right, camera-linked — so it doesn't compete with FLIMKit's Tkinter UI for the main thread. Each voxel with data is one point; a voxel with no data (zero intensity, or no per-pixel fit) has no point at all. This is deliberately not volume rendering: real z-stacks are dominated by background (one export had 92% NaN lifetime voxels), and a volume mapper resamples onto a dense 3D texture before ray casting, which fills scattered single-voxel gaps in from their valid neighbors — verified directly, a masked-out region rendered as solid fill unless it was one large contiguous block. A point cloud has no such resampling step to paper over gaps with.
• Intensity is clipped to its 99th percentile before rendering, the same clip FLIMKit's own 2D intensity view uses, so a few hot pixels don't wash out the color scale.
• The FLIM pane has live sliders for the lifetime min/max color range (defaulting to the 2nd/98th percentile, like FLIMKit's "Auto" scale button) and a colormap picker with the same palette as FLIMKit's 2D FLIM view (hsv, viridis, cool, hot, twilight).
• Tools > Open Saved 3D Volume... reopens a .zarr store from a previous run — no z-stack needs to be loaded for this one, it just opens the viewer against whatever store you point it at.

Install

pip install 'flimkit-zstack-explorer[gui]'

Quote it — in zsh (macOS's default shell), an unquoted [gui] is a glob pattern and the command fails with "no matches found" without installing anything.

[gui] adds PyVista, which does the actual 3D rendering. Without it, the volume-building and OME-Zarr saving still work, but the viewer step will tell you it's missing and how to install it.

Install it into the same Python environment FLIMKit itself runs from — a separate environment or a different python/pip on your PATH will install cleanly but leave FLIMKit unable to see it. Verify with:

python -c "import flimkit_zstack_explorer, pyvista; print('ok')"

run from the same terminal you launch FLIMKit from.

FLIMKit discovers this through the flimkit.plugins entry point, so there's nothing else to wire up. On start it appears under Tools.

From code

from flimkit_zstack_explorer import build_zstack_volumes, save_ome_zarr, load_ome_zarr

# app is FLIMKit's running App instance, with a z-stack loaded in its
# FOV preview panel
intensity_stack, lifetime_stack = build_zstack_volumes(app)
save_ome_zarr('volume.zarr', intensity_stack, lifetime_stack,
              voxel_size_um=(2.0, 0.5, 0.5))

intensity_stack, lifetime_stack = load_ome_zarr('volume.zarr')

To view a store outside FLIMKit:

python -m flimkit_zstack_explorer.viewer --zarr volume.zarr

Why a separate process for the viewer

FLIMKit's UI is Tkinter; PyVista's is VTK. Running VTK's render loop on a background thread inside a Tkinter process is unreliable, especially on macOS, where GUI toolkits generally expect to own the main thread. Building the volume and saving to disk happens inside FLIMKit; the popout viewer is a plain python -m flimkit_zstack_explorer.viewer subprocess reading the saved store, so it gets its own main thread and doesn't touch Tkinter at all.

Development

pip install -e .[gui,test]
pytest

tests/test_volumes.py exercises the z-stack-to-array logic against a fake FOV preview panel, so it runs without Tkinter or a real FLIMKit install. tests/test_zarr_io.py round-trips real arrays through zarr/ome-zarr.