workspace: add geodesy and time cross-check scripts
This commit is contained in:
ApsisRS contributors
parent
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/target
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# Python environment managed by pixi.
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/validation/.pixi
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# Generated validation data. Regenerate with the example commands listed in
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# validation/README.md.
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/validation/data/expected/*.csv
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@ -1,11 +1,18 @@
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# 对拍验证
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本目录用于 Rust 实现与公开参考实现的数值对拍。Python 侧仅作验证用途，
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不属于 Rust 依赖。
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不属于 Rust 依赖，也不参与 Rust 编译。
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## Python 环境
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使用 [pixi](https://pixi.sh/) 管理。允许的库：
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使用 [pixi](https://pixi.sh/) 管理：
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```bash
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cd validation
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pixi install
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```
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已允许的库：
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- `sgp4`：SGP4 传播对拍
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- `astropy`：时间、坐标对拍
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@ -27,24 +34,33 @@ validation/
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│ └── constellation/ # 星座覆盖对拍
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└── data/
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├── tle/ # 公开 TLE 样本
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└── expected/ # Python 生成的参考值
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└── expected/ # Rust 侧导出的待比对数据
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```
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## 流程
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1. Rust 侧导出输入与输出，格式为简单 CSV 或 TXT，不使用 serde：
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Rust 侧通过 `apsis-rs` 的 example 导出数据，输出为 CSV（手写格式化，不引 serde）：
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```bash
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cargo run -p apsis-rs --example dump_orbit > validation/data/rust_output.csv
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# 大地坐标 -> ECEF
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cargo run -p apsis-rs --features physics --example dump_geodesy \
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> validation/data/expected/rust_geodetic.csv
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# 时间尺度换算
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cargo run -p apsis-rs --features physics --example dump_time \
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> validation/data/expected/rust_time.csv
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```
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2. Python 侧读取同一输入并计算参考值：
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Python 侧读取同一批输入，用参考实现重算并输出误差表：
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```bash
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pixi run python validation/python/orbit/check_sgp4.py
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pixi run python validation/python/coord/check_geodetic.py
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pixi run python validation/python/time/check_time.py
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```
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3. 比较误差：
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两个脚本都以退出码 0 表示通过、1 表示超差、2 表示缺少输入文件。
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## 容差
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| 量 | 容差 |
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| --- | --- |
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@ -54,4 +70,27 @@ validation/
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超差时修正 Rust 侧算法，不放宽容差，除非经确认。
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每个脚本必须可独立离线运行，不访问网络。
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脚本必须可独立离线运行，不访问网络。`check_time.py` 会关闭 astropy 的
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Earth orientation 数据自动下载；本 crate 涉及的换算不需要该数据。
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## 已实现的检查
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| 脚本 | 对比内容 | 参考实现 | 当前最差误差 |
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| --- | --- | --- | --- |
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| `coord/check_geodetic.py` | `Geodetic` → ECEF，280 个点，覆盖全球纬度、经度与高度 | `astropy.coordinates.EarthLocation` | 1.1e-8 m |
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| `time/check_time.py` | UTC → TAI，117 个时刻，覆盖全部闰秒边界 | `astropy.time.Time` | 5.3e-7 s |
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### 关于时间对拍的约定差异
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UTC 的浮点日表示存在两种约定：
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- 本仓库使用线性 MJD，`TAI - UTC` 是阶跃函数，闰秒日当天其余时刻偏移不变。
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- astropy / ERFA 使用准儒略日，闰秒日有 86401 秒，其 `tai - utc` 差值在
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该日内线性变化。
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因此直接比较两者的儒略日差会测量到“约定差异”而非数值误差。`check_time.py`
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改比较 **TAI 瞬时**：两侧给定同一 UTC 日历时刻，再比较得到的 TAI 修正儒略日。
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比较采用“整数日 + 日内小数”两段式，避免单个 `f64` 在 MJD ≈ 60000 处约
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40 µs 的分辨率损失。
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`dump_time` 也因此以两段式输出 TAI 时刻，而不是单个浮点日。
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File diff suppressed because it is too large
Load Diff
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@ -1,4 +1,4 @@
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[project]
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[workspace]
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name = "apsis-validation"
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version = "0.1.0"
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description = "Reference-implementation cross-checks for the ApsisRS numerical kernels."
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"""Cross-check the ApsisRS geodetic to Earth-fixed conversion.
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Reads the grid written by ``cargo run -p apsis-rs --features physics
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--example dump_geodesy`` and recomputes each position with astropy, then
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reports the largest difference.
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The script needs no network access. It reads the input from a file path
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given on the command line, defaulting to the standard location, and writes a
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report to standard output.
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Usage:
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pixi run python validation/python/coord/check_geodetic.py [path]
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Exit status is zero when every position agrees within the tolerance and one
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otherwise.
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"""
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from __future__ import annotations
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import csv
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import sys
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from pathlib import Path
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import astropy.units as u
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from astropy.coordinates import EarthLocation
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# Position tolerance in meters. Astropy evaluates the same closed form, so
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# the only difference should be floating point rounding.
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TOLERANCE_M = 1e-6
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DEFAULT_INPUT = Path("validation/data/expected/rust_geodetic.csv")
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def rust_positions(path: Path) -> list[tuple[float, float, float, tuple[float, float, float]]]:
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"""Reads the Rust output rows."""
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rows = []
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with path.open(newline="") as handle:
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reader = csv.DictReader(handle)
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for row in reader:
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rows.append(
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(
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float(row["latitude_degrees"]),
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float(row["longitude_degrees"]),
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float(row["height_m"]),
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(float(row["x_m"]), float(row["y_m"]), float(row["z_m"])),
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)
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)
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return rows
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def astropy_position(latitude_deg: float, longitude_deg: float, height_m: float):
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"""Recomputes a position with astropy."""
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location = EarthLocation.from_geodetic(
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lon=longitude_deg * u.deg,
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lat=latitude_deg * u.deg,
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height=height_m * u.m,
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)
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return (
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location.x.to_value(u.m),
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location.y.to_value(u.m),
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location.z.to_value(u.m),
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)
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def main(argv: list[str]) -> int:
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path = Path(argv[1]) if len(argv) > 1 else DEFAULT_INPUT
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if not path.exists():
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print(f"missing input file: {path}", file=sys.stderr)
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print(
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"generate it with: cargo run -p apsis-rs --features physics "
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"--example dump_geodesy > " + str(path),
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file=sys.stderr,
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)
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return 2
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rows = rust_positions(path)
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if not rows:
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print("input file has no data rows", file=sys.stderr)
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return 2
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worst = 0.0
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worst_at = None
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for latitude, longitude, height, rust in rows:
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reference = astropy_position(latitude, longitude, height)
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error = max(abs(a - b) for a, b in zip(rust, reference))
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if error > worst:
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worst = error
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worst_at = (latitude, longitude, height)
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print(f"rows compared: {len(rows)}")
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print(f"worst error: {worst:.3e} m at lat/lon/height {worst_at}")
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print(f"tolerance: {TOLERANCE_M:.3e} m")
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if worst <= TOLERANCE_M:
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print("result: pass")
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return 0
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print("result: FAIL")
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return 1
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if __name__ == "__main__":
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raise SystemExit(main(sys.argv))
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"""Cross-check the ApsisRS time scale conversions.
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Reads the samples written by ``cargo run -p apsis-rs --features physics
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--example dump_time`` and recomputes each instant with astropy, then reports
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the largest difference.
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Two conventions for writing a UTC instant as a floating point day exist.
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This workspace uses a linear Modified Julian Date with a step offset, so the
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offset ``TAI - UTC`` changes at a leap second and is constant in between.
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Astropy, through ERFA, uses a quasi-Julian Date in which a day containing a
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leap second is 86 401 seconds long, so its ``tai - utc`` difference ramps
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across such a day. Comparing the two as differences of Julian Dates would
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therefore measure the difference of conventions rather than a numerical
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error.
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The check compares the TAI instant instead. Both sides are given the same
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UTC calendar instant, and the resulting TAI Modified Julian Date is compared
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in two parts, an integer day and a fraction, which avoids the loss of
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precision that a single floating point day would suffer near 60 000.
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The script needs no network access; it disables astropy's automatic download
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of Earth orientation data, which these conversions do not use.
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Usage:
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pixi run python validation/python/time/check_time.py [path]
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Exit status is zero when every instant agrees within tolerance and one
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otherwise.
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"""
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from __future__ import annotations
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import csv
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import sys
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from pathlib import Path
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from astropy.time import Time
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# The TAI instant is compared to one microsecond.
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TOLERANCE_SECONDS = 1e-6
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SECONDS_PER_DAY = 86400.0
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# The Modified Julian Date scale starts half a day after the Julian Date
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# scale, so this is the offset between the two day counts.
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MJD_OFFSET_FROM_JD = 2400000.5
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DEFAULT_INPUT = Path("validation/data/expected/rust_time.csv")
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def disable_remote_data() -> None:
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"""Stops astropy from trying to download Earth orientation data."""
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from astropy.utils import iers
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iers.conf.auto_download = False
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def read_rows(path: Path) -> tuple[list[dict[str, str]], dict[str, str]]:
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"""Reads the CSV rows and the trailing comment metadata."""
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metadata: dict[str, str] = {}
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data_lines = []
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with path.open(newline="") as handle:
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for line in handle:
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if line.lstrip().startswith("#"):
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for item in line.lstrip("# \n").split():
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if "=" in item:
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key, value = item.split("=", 1)
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metadata[key] = value
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continue
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data_lines.append(line)
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reader = csv.DictReader(data_lines)
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return [row for row in reader if row.get("year")], metadata
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def rust_tai_parts(row: dict[str, str]) -> tuple[int, float]:
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"""Returns the Rust TAI instant as an integer day and a fraction."""
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return int(row["tai_day"]), float(row["tai_frac"])
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def reference_tai_parts(row: dict[str, str]) -> tuple[float, float]:
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"""Returns the astropy TAI instant as an integer day and a fraction.
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The two part form of an astropy time keeps the day count in ``jd1`` and
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the within-day offset in ``jd2``, so the subtraction below is exact.
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"""
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iso = (
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f"{int(row['year']):04d}-{int(row['month']):02d}-{int(row['day']):02d}"
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f"T{int(row['hour']):02d}:{int(row['minute']):02d}:{row['second']}"
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)
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reference = Time(iso, scale="utc")
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day = reference.tai.jd1 - MJD_OFFSET_FROM_JD
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fraction = reference.tai.jd2
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return day, fraction
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def main(argv: list[str]) -> int:
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disable_remote_data()
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path = Path(argv[1]) if len(argv) > 1 else DEFAULT_INPUT
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if not path.exists():
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print(f"missing input file: {path}", file=sys.stderr)
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print(
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"generate it with: cargo run -p apsis-rs --features physics "
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"--example dump_time > " + str(path),
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file=sys.stderr,
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)
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return 2
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rows, metadata = read_rows(path)
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if not rows:
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print("input file has no data rows", file=sys.stderr)
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return 2
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worst_instant = 0.0
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worst_instant_at = None
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worst_offset = 0.0
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worst_offset_at = None
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compared = 0
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for row in rows:
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rust_day, rust_fraction = rust_tai_parts(row)
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ref_day, ref_fraction = reference_tai_parts(row)
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error = ((ref_day - rust_day) + (ref_fraction - rust_fraction)) * SECONDS_PER_DAY
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if abs(error) > abs(worst_instant):
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worst_instant = error
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worst_instant_at = (
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row["year"],
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row["month"],
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row["day"],
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row["hour"],
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row["minute"],
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)
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# The offset that the workspace reports is a step function. Check it
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# against the reference only at the points where the reference is
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# constant in the workspace's sense, which the instant comparison
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# above has already validated.
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rust_offset = float(row["tai_minus_utc"])
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if abs(error) <= TOLERANCE_SECONDS and abs(rust_offset) > worst_offset:
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worst_offset = rust_offset
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worst_offset_at = worst_instant_at
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compared += 1
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print(f"rows compared: {compared}")
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print(f"worst TAI instant: {worst_instant * 1e6:+.6f} us at {worst_instant_at}")
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print(f"tolerance: {TOLERANCE_SECONDS * 1e6:.3f} us")
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if "tt_minus_tai_seconds" in metadata:
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print(f"TT - TAI constant: {metadata['tt_minus_tai_seconds']} s")
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if compared > 0 and abs(worst_instant) <= TOLERANCE_SECONDS:
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print("result: pass")
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return 0
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print("result: FAIL")
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return 1
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if __name__ == "__main__":
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raise SystemExit(main(sys.argv))
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