Simulator¶

The simulator is designed to help you get started with Lima and to test or explore Lima without any hardware. It generates synthetic frames on-the-fly using configurable pattern generators, and supports MPI-based multi-receiver setups.

Initialization parameters¶

The init_params structure configures the detector at startup.

Parameter	Type	Default	Description
`width`	int	2048	Frame width in pixels
`height`	int	2048	Frame height in pixels

Acquisition parameters¶

The simulator extends the standard hw::acq_params with a det field containing simulator-specific parameters.

Standard parameters (`acq_params.acq`)¶

Parameter	Type	Default	Description
`nb_frames`	int	1	Number of frames to acquire
`expo_time`	duration	1ms	Exposure time
`latency_time`	duration	0ms	Latency between frames
`trigger_mode`	enum	`internal`	Trigger mode: `internal`, `software`, `external`
`nb_frames_per_trigger`	int	1	Number of frames produced per trigger
`acq_mode`	enum	`normal`	Acquisition mode

Detector-specific parameters (`acq_params.det`)¶

Parameter	Type	Default	Description
`generator`	`generator_params`	—	Frame generator configuration
`nb_prefetch_frames`	int	1	Size of the prefetch ring buffer. Increase to simulate high frame rates.
`dropped_frame_idx`	int	0	Frame index after which frames are dropped. `0` disables frame dropping.
`failed_frame_idx`	int	0	Frame index after which acquisition fails. `0` disables failure injection.
`dispatch_mode`	enum	`round_robin`	How frames are dispatched across MPI receivers (see below).

Frame generators¶

The generator is selected via det.generator.type.

Common generator parameters (`generator_params`)¶

Parameter	Type	Default	Description
`type`	enum	`gauss`	Generator type: `gauss` or `diffraction`
`pixel_type`	enum	`gray8`	Pixel format: `gray8`, `gray16`, `gray32`, `gray32f`
`nb_channels`	size_t	1	Number of channels (bands) per frame
`gauss`	`gauss_params`	—	Parameters for the Gauss generator
`diffraction`	`diffraction_params`	—	Parameters for the Diffraction generator
`spiral`	`gauss_params`	—	Spiral parameters is reusing first peak of gaussian generator parameters

Gauss generator (`type = gauss`)¶

Generates frames with one or more Gaussian peaks. Useful for simulating simple spot patterns.

gauss_params

Parameter	Type	Default	Description
`peaks`	`vector<gauss_peak>`	one default peak	List of Gaussian peaks
`grow_factor`	double	0.0	Factor by which peaks grow between frames

gauss_peak

Parameter	Type	Default	Description
`x0`, `y0`	double	1024.0	Center of the peak (pixels)
`fwhm`	double	128.0	Full Width at Half Maximum
`max`	double	100.0	Peak intensity value

Diffraction generator (`type = diffraction`)¶

Generates frames that simulate a diffraction pattern from a moving source.

diffraction_params

Parameter	Type	Default	Description
`x0`, `y0`	double	1024.0	Center of the diffraction pattern (pixels)
`source_pos_x`, `source_pos_y`	double	5.0	Initial source position relative to the pattern center
`source_speed_x`, `source_speed_y`	double	0.0	Source velocity in pixels per frame

Spiral generator (`type = spiral`)¶

Generates frames that simulate a spiral of Gaussian peaks. Usefull to simulate accumulated patterns

Frame dispatch modes¶

In MPI setups the simulator distributes frames across receiver processes. The dispatch_mode controls how:

Mode	Description
`round_robin`	Frames are dispatched sequentially in turn to each receiver (deterministic, balanced).
`predictive_random`	Frames are dispatched pseudo-randomly using a seeded RNG (reproducible across runs).
`full_random`	Frames are dispatched fully randomly with no reproducibility guarantee.

Fault injection¶

The simulator can inject faults to test error handling:

Dropped frames (dropped_frame_idx): Setting this to N > 0 causes the simulator to stop sending frames after frame N. Receivers will detect a missing frame.
Failed acquisition (failed_frame_idx): Setting this to N > 0 causes the acquisition to report a failure after frame N.

Both are disabled by default (value 0).

Prefetching¶

The nb_prefetch_frames parameter controls the size of an internal ring buffer of pre-generated frames. Increasing this value decouples frame generation from frame delivery, which allows the simulator to sustain high frame rates without stalling on generation time. The ring buffer also defines the cycle length: once nb_prefetch_frames frames have been delivered, the sequence repeats from the beginning.

Simulator¶

Initialization parameters¶

Acquisition parameters¶

Standard parameters (acq_params.acq)¶

Detector-specific parameters (acq_params.det)¶