las_utils.py

import numpy as np
import glob
import pathlib
import re
import os
import laspy

from ..utils.labels import Labels


def get_tilecode_from_filename(filename):
    """Extract the tile code from a file name."""
    return re.match(r'.*(\d{4}_\d{4}).*', filename)[1]


def get_bbox_from_tile_code(tile_code, padding=0, width=50, height=50):
    """
    Get the <X,Y> bounding box for a given tile code. The tile code is assumed
    to represent the lower left corner of the tile.

    Parameters
    ----------
    tile_code : str
        The tile code, e.g. 2386_9702.
    padding : float
        Optional padding (in m) by which the bounding box will be extended.
    width : int (default: 50)
        The width of the tile.
    height : int (default: 50)
        The height of the tile.

    Returns
    -------
    tuple of tuples
        Bounding box with inverted y-axis: ((x_min, y_max), (x_max, y_min))
    """
    tile_split = tile_code.split('_')

    # The tile code of each tile is defined as
    # 'X-coordinaat/50'_'Y-coordinaat/50'
    x_min = int(tile_split[0]) * 50
    y_min = int(tile_split[1]) * 50

    return ((x_min - padding, y_min + height + padding),
            (x_min + height + padding, y_min - padding))


def get_bbox_from_las_file(laz_file, padding=0):
    """
    Get the <X,Y> bounding box for a given CycloMedia laz file, based on the
    filename.

    Parameters
    ----------
    laz_file : Path or str
        the .laz filename, e.g. filtered_2386_9702.laz
    padding : float
        Optional padding (in m) by which the bounding box will be extended.

    Returns
    -------
    tuple of tuples
        Bounding box with inverted y-axis: ((x_min, y_max), (x_max, y_min))
    """
    if type(laz_file) == str:
        laz_file = pathlib.Path(laz_file)
    tile_code = get_tilecode_from_filename(laz_file.name)

    return get_bbox_from_tile_code(tile_code, padding=padding)


def get_bbox_from_las_folder(folder_path, padding=0):
    """
    Get the <X,Y> bounding box for a given folder of CycloMedia LAS files.

    Parameters
    ----------
    folder_path : str or Path
        The folder name.
    padding : int (default: 0)
        Optional padding (in meters).

    Returns
    -------
    tuple of tuples
        Bounding box with inverted y-axis: ((x_min, y_max), (x_max, y_min))
    """
    x_min = y_min = 1e6
    x_max = y_max = 0
    file_types = ('.LAS', '.las', '.LAZ', '.laz')

    for file in [f for f in glob.glob(os.path.join(folder_path, '*'))
                 if f.endswith(file_types)]:
        bbox = get_bbox_from_las_file(file)
        x_min = min(x_min, bbox[0][0])
        x_max = max(x_max, bbox[1][0])
        y_min = min(y_min, bbox[1][1])
        y_max = max(y_max, bbox[0][1])

    return ((x_min-padding, y_max+padding), (x_max+padding, y_min-padding))


def get_stats(labels):
    """Returns a string describing statistics based on labels."""
    N = len(labels)
    labels, counts = np.unique(labels, return_counts=True)
    stats = f'Total: {N:25} points\n'
    for label, cnt in zip(labels, counts):
        name = Labels.get_str(label)
        perc = (float(cnt) / N) * 100
        stats += f'Class {label:2}, {name:14} ' +\
                 f'{cnt:7} points ({perc:4.1f} %)\n'
    return stats


def read_las(las_file):
    """Read a las file and return the las object."""
    return laspy.read(las_file)


def label_and_save_las(las, labels, outfile):
    """Label a las file using the provided class labels and save to outfile."""
    assert len(labels) == las.header.point_count
    if 'label' not in las.point_format.extra_dimension_names:
        las.add_extra_dim(laspy.ExtraBytesParams(name="label", type="uint16",
                          description="Labels"))
    las.label = labels
    las.write(outfile)