New: pixel per degree calculator

This commit is contained in:
Akemi Izuko 2023-12-23 20:14:13 -07:00
parent 95f08c747d
commit 3cdbe44c33
Signed by: akemi
GPG key ID: 8DE0764E1809E9FC

134
bin/ppd.py Executable file
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#!/usr/bin/env python3
# Pixels per degree calculator
#
import re
import math
import argparse
from typing import *
def diag_to_dims(diag: float, aspect_w: int, aspect_h: int) -> Tuple[float, float]:
aspect_sq_sum = aspect_w**2 + aspect_h**2
x = math.sqrt(diag**2 / aspect_sq_sum)
return aspect_w * x, aspect_h * x
def inch2cm(inch: float) -> float:
return inch * 2.54
def deg2rad(deg: float) -> float:
return deg * math.pi / 180
def rad2deg(rad: float) -> float:
return rad * 180 / math.pi
def ppd_min(info: dict) -> float:
"""
Computes the ppd exactly 1deg off from the center
This results in a lower bound on the PPD. All distance measures are in cm
"""
lw, lh = diag_to_dims(info.diag, info.asc_w, info.asc_h)
screen_dist = math.tan(deg2rad(1)) * info.eye_dist
print(screen_dist)
return screen_dist * info.res_w / lw
def ppd_avg(info: dict) -> float:
"""
Computes the ppd using the entire width of the screen
This results in an average of the PPD. All distance measures are in cm
"""
lw, lh = diag_to_dims(info.diag, info.asc_w, info.asc_h)
angle = 2 * rad2deg(math.atan((lw/2) / info.eye_dist))
print(f"FOV: {angle}")
return info.res_w / angle
def ppd_max(info: dict) -> float:
lw, _ = diag_to_dims(info.diag, info.asc_w, info.asc_h)
h = math.sqrt((lw/2)**2 + info.eye_dist**2)
a = h - info.eye_dist
o = info.eye_dist * math.tan(deg2rad(1))
print(h)
h_s = math.sqrt(a**2 + o**2) * (info.res_w / lw)
return h_s
h = math.sqrt(info.eye_dist**2 + (lw/2)**2)
#print(h)
#print(info.eye_dist)
interior_adj = h - info.eye_dist
interior_opp = info.eye_dist * math.tan(deg2rad(1))
print(interior_adj)
print(interior_opp)
print(lw)
return math.sqrt(interior_adj**2 + interior_opp**2) * info.res_w / lw
interior_obtuse = 90.0 - rad2deg(math.atan((lw/2) / info.eye_dist))
#interior_obtuse = 180.0 - 1.0 - interior_acute
interior_angle = deg2rad(89.0 + rad2deg(math.atan((lw/2) / info.eye_dist)))
interior_adj = h - info.eye_dist
screen_length = interior_adj / math.cos(interior_angle)
return screen_length * info.res_w
if __name__ == "__main__":
parser = argparse.ArgumentParser(
prog="PPD calculator v1.0.0",
description="Calculate the pixels per degree on a flat screen"
);
parser.add_argument(
"diag", type=float,
help="Diagonal meansure of screen in inches"
);
parser.add_argument(
"res_w", type=int,
help="Horizontal resolution of screen"
);
parser.add_argument(
"res_h", type=int,
help="Vertical resolution of screen"
);
parser.add_argument(
"asc_w", type=int,
help="Horizontal aspect ratio"
);
parser.add_argument(
"asc_h", type=int,
help="Vertical aspect ratio"
);
parser.add_argument(
"eye_dist", type=int,
help="Distance of your eyes from the screen in centimeters"
);
args = parser.parse_args();
args.diag = inch2cm(args.diag)
print(f"Pixels per degree (min): {ppd_min(args)}")
print(f"Pixels per degree (avg): {ppd_avg(args)}")
print(f"Pixels per degree (max): {ppd_max(args)}")