kopia lustrzana https://github.com/OpenDroneMap/ODM
73 wiersze
2.5 KiB
Python
73 wiersze
2.5 KiB
Python
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import os
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import json
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import numpy as np
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def opensfm_reconstruction_average_gsd(reconstruction_json):
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"""
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Computes the average Ground Sampling Distance of an OpenSfM reconstruction.
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:param reconstruction_json path to OpenSfM's reconstruction.json
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:return Ground Sampling Distance value (cm / pixel) or None if
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a GSD estimate cannot be compute
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"""
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if not os.path.isfile(reconstruction_json):
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raise FileNotFoundError(reconstruction_json + " does not exist.")
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with open(reconstruction_json) as f:
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data = json.load(f)
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# Calculate median height from sparse reconstruction
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reconstruction = data[0]
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point_heights = []
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for pointId in reconstruction['points']:
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point = reconstruction['points'][pointId]
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point_heights.append(point['coordinates'][2])
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ground_height = np.median(point_heights)
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gsds = []
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for shotImage in reconstruction['shots']:
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shot = reconstruction['shots'][shotImage]
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if shot['gps_dop'] < 999999:
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camera = reconstruction['cameras'][shot['camera']]
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shot_height = shot['translation'][2]
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focal_ratio = camera['focal']
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gsds.append(calculate_gsd_from_focal_ratio(focal_ratio,
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shot_height - ground_height,
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camera['width']))
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return np.mean(gsds) if len(gsds) > 0 else None
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def calculate_gsd(sensor_width, flight_height, focal_length, image_width):
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"""
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:param sensor_width in millimeters
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:param flight_height in meters
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:param focal_length in millimeters
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:param image_width in pixels
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:return Ground Sampling Distance
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>>> round(calculate_gsd(13.2, 100, 8.8, 5472), 2)
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2.74
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>>> calculate_gsd(13.2, 100, 0, 2000)
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>>> calculate_gsd(13.2, 100, 8.8, 0)
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"""
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if sensor_width != 0:
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return calculate_gsd_from_focal_ratio(focal_length / sensor_width,
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flight_height,
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image_width)
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else:
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return None
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def calculate_gsd_from_focal_ratio(focal_ratio, flight_height, image_width):
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"""
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:param focal_ratio focal length (mm) / sensor_width (mm)
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:param flight_height in meters
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:param image_width in pixels
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:return Ground Sampling Distance
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"""
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if focal_ratio == 0 or image_width == 0:
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return None
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return ((flight_height * 100) / image_width) / focal_ratio
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