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Rework wind speed Weibull inputs, tune.

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The previous method of using a uniform scalar of the MSL wind speed for
higher altitudes didn't offer enough control. In particular, the shape
needs to be quite different to skew low, mid, high.

This patch reworks that system so the parameters of each distribution
are configured per-altitude level. To keep some continuity between
altitudes (on a windy day, all levels should have higher wind speeds on
average), the wind speed of the lower altitude will be added to the
scale value of the higher altitude.

Since it wasn't practical to approximate the previous behavior with the
new system, this also handles the tuning of each. The low altitude
speeds remain mostly unchanged (typically around 5 knots expect for
thunderstorms), but the average speeds for other altitudes went up to
more closely match the previous intent but without the massive
overshoot. At 2000m wind speeds are typically in the 20-25 knot range
now, and 8000m 30-50 knots.

https://www.quora.com/What-is-the-average-wind-speed-at-different-altitudes
has some of the source data, and Quora is the most authoritative source
there is. It claims that cruise altitude winds can get "as high as 150
knots", but doesn't claim anything about the average. I had a
surprisingly difficult time finding good data for cruise altitude air
speeds for non-jet stream paths (though many of our maps are in jet
streams), so I just eyeballed it from
https://turbli.com/wind-during-flights/.

https://github.com/dcs-liberation/dcs_liberation/issues/2861

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2863.
This commit is contained in:
Dan Albert 2023-05-15 22:21:34 -07:00
parent 78e2da9196
commit eb31a0f038
1 changed files with 38 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
game/weather.py
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@ -49,6 +49,12 @@ class WindConditions:
at_8000m: Wind
@dataclass(frozen=True)
class WeibullWindSpeedParameters:
shape: float
scale: Speed
@dataclass(frozen=True)
class Clouds:
base: int
@ -181,10 +187,9 @@ class Weather:
@staticmethod
def random_wind(
weibull_shape: float,
weibull_scale_speed: Speed,
at_2000m_factor_range: tuple[float, float],
at_8000m_factor_range: tuple[float, float],
params_at_msl: WeibullWindSpeedParameters,
params_at_2000m: WeibullWindSpeedParameters,
params_at_8000m: WeibullWindSpeedParameters,
) -> WindConditions:
"""Generates random wind."""
wind_direction = Heading.random()
@ -195,10 +200,14 @@ class Weather:
# value.
# https://www.itl.nist.gov/div898/handbook/eda/section3/weibplot.htm
msl = random.weibullvariate(
weibull_scale_speed.meters_per_second, weibull_shape
params_at_msl.scale.meters_per_second, params_at_msl.shape
)
at_2000m = random.weibullvariate(
msl + params_at_2000m.scale.meters_per_second, params_at_2000m.shape
)
at_8000m = random.weibullvariate(
at_2000m + params_at_8000m.scale.meters_per_second, params_at_8000m.shape
)
at_2000m_factor = random.uniform(*at_2000m_factor_range)
at_8000m_factor = random.uniform(*at_8000m_factor_range)
# DCS is limited to 97 knots wind speed.
max_supported_wind_speed = knots(97).meters_per_second
@ -208,11 +217,11 @@ class Weather:
at_0m=Wind(wind_direction.degrees, max(1.0, msl)),
at_2000m=Wind(
wind_direction_2000m.degrees,
min(max_supported_wind_speed, msl * at_2000m_factor),
min(max_supported_wind_speed, at_2000m),
),
at_8000m=Wind(
wind_direction_8000m.degrees,
min(max_supported_wind_speed, msl * at_8000m_factor),
min(max_supported_wind_speed, at_8000m),
),
)
@ -312,7 +321,11 @@ class ClearSkies(Weather):
return None
def generate_wind(self) -> WindConditions:
return self.random_wind(1.5, knots(5), (1, 1.8), (1.5, 2.5))
return self.random_wind(
WeibullWindSpeedParameters(1.5, knots(5)),
WeibullWindSpeedParameters(3.5, knots(20)),
WeibullWindSpeedParameters(6.4, knots(20)),
)
class Cloudy(Weather):
@ -336,7 +349,11 @@ class Cloudy(Weather):
return None
def generate_wind(self) -> WindConditions:
return self.random_wind(1.6, knots(6.5), (1, 1.8), (1.5, 2.5))
return self.random_wind(
WeibullWindSpeedParameters(1.6, knots(6.5)),
WeibullWindSpeedParameters(3.5, knots(22)),
WeibullWindSpeedParameters(6.4, knots(18)),
)
class Raining(Weather):
@ -360,7 +377,11 @@ class Raining(Weather):
return None
def generate_wind(self) -> WindConditions:
return self.random_wind(2.6, knots(12), (1, 1.7), (2.2, 2.8))
return self.random_wind(
WeibullWindSpeedParameters(2.6, knots(8)),
WeibullWindSpeedParameters(4.2, knots(20)),
WeibullWindSpeedParameters(6.4, knots(20)),
)
class Thunderstorm(Weather):
@ -385,7 +406,11 @@ class Thunderstorm(Weather):
)
def generate_wind(self) -> WindConditions:
return self.random_wind(6, knots(20), (1, 2), (2.5, 3.5))
return self.random_wind(
WeibullWindSpeedParameters(6, knots(20)),
WeibullWindSpeedParameters(6.2, knots(20)),
WeibullWindSpeedParameters(6.4, knots(20)),
)
@dataclass