magni.imaging.measurements._zigzag module

Module providing public functions for the magni.imaging.measurements subpackage.

Routine listings

zigzag_sample_image(h, w, scan_length, num_points, angle=np.pi / 20)

Function for zigzag sampling an image.

zigzag_sample_surface(l, w, speed, sample_rate, time, angle=np.pi / 20)

Function for zigzag sampling a surface.

magni.imaging.measurements._zigzag.zigzag_sample_image(h, w, scan_length, num_points, angle=0.15707963267948966)

Sample an image using a zigzag pattern.

The coordinates (in units of pixels) resulting from sampling an image of size h times w using a zigzag pattern are determined. The scan_length determines the length of the path scanned whereas num_points indicates the number of samples taken on that path.

Parameters:

• h (int) – The height of the area to scan in units of pixels.
• w (int) – The width of the area to scan in units of pixels.
• scan_length (float) – The length of the path to scan in units of pixels.
• num_points (int) – The number of samples to take on the scanned path.
• angle (float) – The angle measured in radians by which the lines deviate from being horizontal (the default is pi / 20).

Returns:

coords (ndarray) – The coordinates of the samples arranged into a 2D array, such that each row is a coordinate pair (x, y).

Notes

The orientation of the coordinate system is such that the width w is measured along the x-axis whereas the height h is measured along the y-axis.

The angle is measured clockwise relative to horizontal and is limited to the interval \(\left(0;\arctan\left(\frac{h}{w}\right)\right)\).

Examples

For example,

>>> import numpy as np
>>> from magni.imaging.measurements import zigzag_sample_image
>>> h = 10
>>> w = 10
>>> scan_length = 50.0
>>> num_points = 12
>>> np.set_printoptions(suppress=True)
>>> zigzag_sample_image(h, w, scan_length, num_points)
array([[ 0.5       ,  0.5       ],
       [ 4.98949246,  1.21106575],
       [ 9.47898491,  1.9221315 ],
       [ 5.03152263,  2.63319725],
       [ 0.54203017,  3.344263  ],
       [ 4.94746229,  4.05532875],
       [ 9.43695474,  4.7663945 ],
       [ 5.0735528 ,  5.47746025],
       [ 0.58406034,  6.188526  ],
       [ 4.90543212,  6.89959175],
       [ 9.39492457,  7.6106575 ],
       [ 5.11558297,  8.32172325]])

magni.imaging.measurements._zigzag.zigzag_sample_surface(l, w, speed, sample_rate, time, angle=0.15707963267948966)

Sample a surface area using a zigzag pattern.

The coordinates (in units of meters) resulting from sampling an area of size l times w using a zigzag pattern are determined. The scanned path is determined from the probe speed and the scan time.

Parameters:

• l (float) – The length of the area to scan in units of meters.
• w (float) – The width of the area to scan in units of meters.
• speed (float) – The probe speed in units of meters/second.
• sample_rate (float) – The sample rate in units of Hertz.
• time (float) – The scan time in units of seconds.
• angle (float) – The angle measured in radians by which the lines deviate from being horizontal (the default is pi / 20).

Returns:

coords (ndarray) – The coordinates of the samples arranged into a 2D array, such that each row is a coordinate pair (x, y).

Notes

The orientation of the coordinate system is such that the width w is measured along the x-axis whereas the length l is measured along the y-axis.

The angle is measured clockwise relative to horizontal and is limited to the interval \(\left(0;\arctan\left(\frac{h}{w}\right)\right)\).

Examples

For example,

>>> import numpy as np
>>> from magni.imaging.measurements import zigzag_sample_surface
>>> l = 1e-6
>>> w = 1e-6
>>> speed = 7e-7
>>> sample_rate = 1.0
>>> time = 12.0
>>> np.set_printoptions(suppress=True)
>>> zigzag_sample_surface(l, w, speed, sample_rate, time)
array([[ 0.        ,  0.        ],
       [ 0.00000069,  0.00000011],
       [ 0.00000062,  0.00000022],
       [ 0.00000007,  0.00000033],
       [ 0.00000077,  0.00000044],
       [ 0.00000054,  0.00000055],
       [ 0.00000015,  0.00000066],
       [ 0.00000084,  0.00000077],
       [ 0.00000047,  0.00000088],
       [ 0.00000022,  0.00000099],
       [ 0.00000091,  0.0000009 ],
       [ 0.00000039,  0.0000008 ],
       [ 0.0000003 ,  0.00000069]])