python-parakeet 0.2.3

A phantom generator

parakeet

Parakeet is a digital twin for cryo electron tomography and stands for Program for Analysis and Reconstruction of Artificial data for Kryo ElEctron Tomography

Installation

In order to build this package, the following dependencies are required:

• The CUDA toolkit
• FFTW

To install from the github repository ensure you have the latest version of pip installed and do the following

export CUDACXX=${PATH_TO_CUDA}/bin/nvcc
python -m pip install git+https://github.com/rosalindfranklininstitute/amplus-digital-twin.git@master

To install from source, clone this repository. The repository has a submodule for pybind11 so after cloning the repository run

git submodule update --init --recursive

Then do the following:

export CUDACXX=${PATH_TO_CUDA}/bin/nvcc
python -m pip install .

If you would like to run the tests then, clone this repository and then do the following:

export CUDACXX=${PATH_TO_CUDA}/bin/nvcc
python -m pip install .[test]

Installation for developers

To install for development, clone this repository and then do the following:

export CUDACXX=${PATH_TO_CUDA}/bin/nvcc
python -m pip install -e .

Testing

To run the tests, follow the installation instructions for developers and then do the following:

pytest

Usage

Simulation of datasets is split into a number of different commands. Each command takes a set of command line options or a configuration file in YAML format.

Show default configuration

The default configuration parameters can be seen by typing the following command:

parakeet.show_config

This will give some output like the following which can then be copied to a yaml file (e.g. config.yaml):

Configuration:
    cluster:
        max_workers: 1
        method: null
    device: gpu
    microscope:
        beam:
            acceleration_voltage_spread: 8.0e-07
            drift: null
            electrons_per_angstrom: 30
            energy: 300
            energy_spread: 3.3e-07
        detector:
            dqe: true
            nx: 4000
            ny: 4000
            pixel_size: 1
        model: null
        objective_lens:
            c_10: 20000
            c_12: 0.0
            c_21: 0.0
            c_23: 0.0
            c_30: 2.7
            c_32: 0.0
            c_34: 0.0
            c_41: 0.0
            c_43: 0.0
            c_45: 0.0
            c_50: 0.0
            c_52: 0.0
            c_54: 0.0
            c_56: 0.0
            c_c: 2.7
            current_spread: 3.3e-07
            inner_aper_ang: 0.0
            m: 0
            outer_aper_ang: 0.0
            phi_12: 0.0
            phi_21: 0.0
            phi_23: 0.0
            phi_32: 0.0
            phi_34: 0.0
            phi_41: 0.0
            phi_43: 0.0
            phi_45: 0.0
            phi_52: 0.0
            phi_54: 0.0
            phi_56: 0.0
        phase_plate: false
    sample:
        box:
        - 4000
        - 4000
        - 4000
        centre:
        - 2000
        - 2000
        - 2000
        coords:
            filename: null
            recentre: false
        ice:
            density: 940
            generate: false
        molecules:
            4v1w: 0
            4v5d: 0
            6qt9: 0
        shape:
            cube:
                length: 4000
            cuboid:
                length_x: 4000
                length_y: 4000
                length_z: 4000
            cylinder:
                length: 10000
                radius: 1500
            type: cube
    scan:
        axis:
        - 0
        - 1
        - 0
        exposure_time: 1
        mode: still
        num_images: 1
        start_angle: 0
        start_pos: 0
        step_angle: 10
        step_pos: auto
    simulation:
        division_thickness: 100
        ice: false
        margin: 100
        padding: 100
        slice_thickness: 3.0

Generate sample model

Once the configuration file has been generated a new sample file can be created with the following command:

parakeet.sample.new -c config.yaml

This will result in a file "sample.h5" being generated. This file contains information about the size and shape of the sample but as yet doesn't contain any atomic coordinates. The atomic model is added by running the following command which adds molecules to the sample file. If a single molcule is specified then it will be placed in the centre of the sample volume. If multiple molecules are specified then the molecules will be positioned at random locations in the sample volume. This command will update the "sample.h5" file with the atomic coordinates but will not generated any new files.

parakeet.sample.add_molecules -c config.yaml

Simulate EM images

Once the atomic model is ready, the EM images can be simulated with the following commands. Each stage of the simulation is separated because it may be desirable to simulate many different defocused images from the sample exit wave for example or many different doses for the sample defocusses image. Being separate, the output of one stage can be reused for multiple runs of the next stage. The first stage is to simulate the exit wave. This is the propagation of the electron wave through the sample. It is therefore the most computationally intensive part of the processes since the contribution of all atoms within the sample needs to be calculated.

parakeet.simulate.exit_wave -c config.yaml

This command will generate a file "exit_wave.h5" which will contain the exit wave of all tilt angles. The next step is to simulate the micropscope optics which is done with the following command:

parakeet.simulate.optics -c config.yaml

This step is much quicker as it only scales with the size of the detector image and doesn't require the atomic coordinates again. The command will output a file "optics.h5". Finally, the response of the detector can be simulated with the following command:

parakeet.simulate.image -c config.yaml

This command will add the detector DQE and the Poisson noise for a given dose and will output a file "image.h5".

Other functions

Typically we cant to output an MRC file for further processing. The hdf5 files can easily be exported to MRC by the following command:

parakeet.export file.h5 -o file.mrc

The export command can also be used to rebin the image or select a region of interest.

Issues

Please use the GitHub issue tracker to submit bugs or request features.

License

Copyright Diamond Light Source and Rosalind Franklin Institute, 2019.

Distributed under the terms of the GPLv3 license, parakeet is free and open source software.