gprMax/tools/convert_png2h5.py

# Copyright (C) 2015-2023: The University of Edinburgh
#                 Authors: Craig Warren and Antonis Giannopoulos
#
# This file is part of gprMax.
#
# gprMax is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# gprMax is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with gprMax.  If not, see <http://www.gnu.org/licenses/>.

import argparse
import os

import h5py
import matplotlib.image as mpimg
import matplotlib.pyplot as plt
import numpy as np


class Cursor(object):
    """Get RGB(A) value of pixel at x,y coordinate of button press and store in a list."""

    def __init__(self, im, materials):
        """
        Args:
            im (ndarray): Pixels of the image.
            materials (list): To store selected RGB(A) values of selected pixels.
        """
        self.im = im
        self.materials = materials
        plt.connect('button_press_event', self)

    def __call__(self, event):
        """
        Args:
            event (MouseEvent): matplotlib mouse event.
        """
        if not event.dblclick:
            x, y = event.xdata, event.ydata
            if x is not None and y is not None:
                pixel = self.im[int(y), int(x)]
                pixel = np.floor(pixel * 255).astype(np.int16) # Convert pixel values from float (0-1) to integer (0-255)
                match = pixel_match(materials, pixel)
                if match is False:
                    print('x, y: {} {} px; RGB: {}; material ID: {}'.format(int(x), int(y), pixel[:-1], len(self.materials)))
                    materials.append(pixel)

def pixel_match(pixellist, pixeltest):
    """Checks if the RGB(A) value of a pixel already exists in a list of pixel values.

    Args:
        pixellist (list): List of numpy arrays of pixels to test against.
        pixeltest (ndarray): RGB(A) value of test pixel.

    Returns:
        match (boolean): True if pixel is matched in pixel list or False if not found.
    """
    match = False
    for pixel in pixellist:
        if np.all(pixel == pixeltest):
            match = True
            break
    return match


if __name__ == "__main__":

    # Parse command line arguments
    parser = argparse.ArgumentParser(description='Convert a PNG image to a HDF5 file that can be used to import geometry (#geometry_objects_read) into a 2D gprMax model. Colours from the image are selected which correspond to a list of materials that should be supplied in a separate text file.', usage='python convert_png2h5.py imagefile dx dy dz')
    parser.add_argument('imagefile', help='name of image file including path')
    parser.add_argument('dxdydz', type=float, action='append', nargs=3, help='spatial resolution of model, e.g. dx dy dz')
    parser.add_argument('-zcells', default=1, type=int, help='number of cells for domain in z-direction (infinite direction)')
    args = parser.parse_args()

    # Open image file
    im = mpimg.imread(args.imagefile)

    # Store image data to use for creating geometry
    imdata = np.rot90(im, k=3) # Rotate 90CW
    imdata = np.floor(imdata * 255).astype(np.int16) # Convert pixel values from float (0-1) to integer (0-255)

    print('Reading PNG image file: {}'.format(os.path.split(args.imagefile)[1]))
    print(' 1. Select discrete material colours by clicking on parts of the image.\n 2. When all materials have been selected close the image.')

    # List to hold selected RGB values from image
    materials = []

    # Plot image and record rgb values from mouse clicks
    fig = plt.figure(num=os.path.split(args.imagefile)[1], facecolor='w', edgecolor='w')
    im = np.flipud(im) # Flip image for viewing with origin in lower left
    plt.imshow(im, interpolation='nearest', aspect='equal', origin='lower')
    Cursor(im, materials)
    plt.show()

    # Format spatial resolution into tuple
    dx_dy_dz = (args.dxdydz[0][0], args.dxdydz[0][1], args.dxdydz[0][2])

    # Filename for geometry (HDF5) file
    hdf5file = os.path.splitext(args.imagefile)[0] + '.h5'

    # Array to store geometry data (initialised as background, i.e. -1)
    data = np.ones((imdata.shape[0], imdata.shape[1], args.zcells), dtype=np.int16) * -1

    # Write geometry (HDF5) file
    with h5py.File(hdf5file, 'w') as fout:

        # Add attribute with name 'dx_dy_dz' for spatial resolution
        fout.attrs['dx_dy_dz'] = dx_dy_dz

        # Use a boolean mask to match selected pixel values with position in image
        for i, material in enumerate(materials):
            mask = np.all(imdata == material, axis=-1)
            data[mask,:] = i

        # Write data to file
        fout.create_dataset('data', data=data)

    print('Written HDF5 file: {}'.format(os.path.split(hdf5file)[1]))