Referential

Geometric Coordinate system

NXtomo

The tomotools suite is compatible with the NXtomo format as input file format of the raw data.

NeXus uses the McStas coordinate system. Make sure your NXtomo files follow the same conventions. See the coordinate_system section.

Internal coordinate system

Internally the followed coordinate system (by all the tomotools components) is the ‘ESRf’ coordinate system. This is the job of intermediary layer (tomoscan) to

Detector Frame referential

Frames may contain information about flips (left‑right, up‑down). This flip information is interpreted only by NABU during the reconstruction step.

Tomwer works with frames in the raw‑frame reference. “Raw” refers to the as-acquired array space of detector frames exactly as stored in the file before any software processing (no dark/flat normalization, no logarithm, no filtering, no rotation/flip, no binning/resampling, no distortion correction, no phase retrieval, no re-centering). Consequently, all operations that depend on the geometry of the data (e.g., estimating the centre of rotation) must be performed in the raw‑frame reference system as well.

Reduced dark and flat frames are also stored unflipped, so the flip metadata does not interfere with flat‑field normalisation.