80 lines
2.0 KiB
Python
80 lines
2.0 KiB
Python
import math
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def fixation_radius_normalized(
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theta_deg: float,
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distance_cm: float,
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screen_width_cm: float,
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screen_height_cm: float,
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resolution_x: int,
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resolution_y: int,
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method: str = "max",
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):
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"""
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Compute the PyGaze fixation radius for normalized gaze data in [0, 1].
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"""
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# Visual angle to physical distance (cm)
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delta_cm = 2 * distance_cm * math.tan(math.radians(theta_deg) / 2)
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# Physical distance to pixels
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delta_px_x = delta_cm * (resolution_x / screen_width_cm)
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delta_px_y = delta_cm * (resolution_y / screen_height_cm)
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# Pixel radius
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if method == "max":
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r_px = max(delta_px_x, delta_px_y)
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else:
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r_px = math.sqrt(delta_px_x**2 + delta_px_y**2)
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# Pixel radius to normalized radius
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r_norm_x = r_px / resolution_x
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r_norm_y = r_px / resolution_y
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if method == "max":
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return max(r_norm_x, r_norm_y)
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return math.sqrt(r_norm_x**2 + r_norm_y**2)
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def run_example():
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# Example: 55" 4k monitor
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screen_width_cm = 3 * 121.8
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screen_height_cm = 68.5
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resolution_x = 3 * 3840
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resolution_y = 2160
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distance_to_screen_cm = 120
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max_angle = 1.0
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maxdist_px = fixation_radius_normalized(
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theta_deg=max_angle,
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distance_cm=distance_to_screen_cm,
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screen_width_cm=screen_width_cm,
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screen_height_cm=screen_height_cm,
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resolution_x=resolution_x,
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resolution_y=resolution_y,
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method="max",
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)
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print("PyGaze max_dist (max):", maxdist_px)
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maxdist_px = fixation_radius_normalized(
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theta_deg=max_angle,
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distance_cm=distance_to_screen_cm,
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screen_width_cm=screen_width_cm,
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screen_height_cm=screen_height_cm,
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resolution_x=resolution_x,
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resolution_y=resolution_y,
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method="euclid",
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)
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print("PyGaze max_dist (euclid):", maxdist_px)
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def main():
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run_example()
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if __name__ == "__main__":
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main()
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# Reference
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# https://osdoc.cogsci.nl/4.0/de/visualangle/
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# https://reference.org/facts/Visual_angle/LUw29zy7
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