127 lines
4.4 KiB
Python
127 lines
4.4 KiB
Python
import numpy as np
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import matplotlib.pyplot as plt
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from skimage.morphology import remove_small_holes
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from PIL import Image
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from skimage.draw import line_aa
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class Map:
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def __init__(self, file_path, threshold_occupied=100,
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origin=(-30.0, -24.0), resolution=0.06):
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"""
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Constructor for map object. Map contains occupancy grid map data of
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environment as well as meta information.
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:param file_path: path to image of map
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:param threshold_occupied: threshold value for binarization of map
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image
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:param origin: x and y coordinates of map origin in world coordinates
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[m]
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:param resolution: resolution in m/px
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"""
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# Set binarization threshold
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self.threshold_occupied = threshold_occupied
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# Numpy array containing map data
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self.data = np.array(Image.open(file_path))[:, :, 0]
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# Process raw map image
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self.process_map()
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# Store meta information
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self.height = self.data.shape[0] # height of the map in px
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self.width = self.data.shape[1] # width of the map in px
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self.resolution = resolution # resolution of the map in m/px
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self.origin = origin # x and y coordinates of map origin
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# (bottom-left corner) in m
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# Containers for user-specified additional obstacles and boundaries
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self.obstacles = list()
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self.boundaries = list()
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def w2m(self, x, y):
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"""
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World2Map. Transform coordinates from global coordinate system to
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map coordinates.
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:param x: x coordinate in global coordinate system
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:param y: y coordinate in global coordinate system
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:return: discrete x and y coordinates in px
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"""
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dx = int(np.floor((x - self.origin[0]) / self.resolution))
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dy = int(np.floor((y - self.origin[1]) / self.resolution))
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return dx, dy
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def m2w(self, dx, dy):
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"""
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Map2World. Transform coordinates from map coordinate system to
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global coordinates.
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:param dx: x coordinate in map coordinate system
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:param dy: y coordinate in map coordinate system
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:return: x and y coordinates of cell center in global coordinate system
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"""
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x = (dx + 0.5) * self.resolution + self.origin[0]
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y = (dy + 0.5) * self.resolution + self.origin[1]
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return x, y
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def add_obstacles(self, obstacles):
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"""
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Add obstacles to the map.
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:param obstacles: list of obstacle objects
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"""
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# Extend list of obstacles
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self.obstacles.extend(obstacles)
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# Iterate over list of new obstacles
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for obstacle in obstacles:
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# Compute radius of circular object in pixels
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radius_px = int(np.ceil(obstacle.radius / self.resolution))
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# Get center coordinates of obstacle in map coordinates
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cx_px, cy_px = self.w2m(obstacle.cx, obstacle.cy)
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# Add circular object to map
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y, x = np.ogrid[-radius_px: radius_px, -radius_px: radius_px]
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index = x ** 2 + y ** 2 <= radius_px ** 2
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self.data[cy_px-radius_px:cy_px+radius_px, cx_px-radius_px:
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cx_px+radius_px][index] = 0
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def add_boundary(self, boundaries):
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"""
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Add boundaries to the map.
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:param boundaries: list of tuples containing coordinates of boundaries'
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start and end points
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"""
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# Extend list of boundaries
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self.boundaries.extend(boundaries)
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# Iterate over list of boundaries
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for boundary in boundaries:
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sx = self.w2m(boundary[0][0], boundary[0][1])
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gx = self.w2m(boundary[1][0], boundary[1][1])
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path_x, path_y, _ = line_aa(sx[0], sx[1], gx[0], gx[1])
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for x, y in zip(path_x, path_y):
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self.data[y, x] = 0
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def process_map(self):
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"""
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Process raw map image. Binarization and removal of small holes in map.
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"""
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# Binarization using specified threshold
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# 1 corresponds to free, 0 to occupied
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self.data = np.where(self.data >= self.threshold_occupied, 1, 0)
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# Remove small holes in map corresponding to spurious measurements
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self.data = remove_small_holes(self.data, area_threshold=5,
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connectivity=8).astype(np.int8)
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if __name__ == '__main__':
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map = Map('map_floor2.png')
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plt.imshow(map.data, cmap='gray')
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plt.show()
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