# navigo
[](https://github.com/totorototo/navigo/actions/workflows/ci.yml)
[](https://crates.io/crates/navigo)
[](https://docs.rs/navigo)
[](LICENSE)
GPS/geospatial analysis in Rust — trace processing, GPX parsing, Minetti pace model, race route analysis, and live recalibration.
# api / usage
## location
A location is a GPS coordinate defined by a longitude, a latitude, and an altitude.
```rust
let location = Location {
longitude: 2.350987,
latitude: 48.856667,
altitude: 890.0,
};
```
- **distance to another location** (km):
```rust
let distance: f64 = paris.calculate_distance_to(&moscow);
```
- **bearing to another location** (degrees):
```rust
let bearing: f64 = paris.calculate_bearing_to(&moscow);
```
- **elevation change to another location**:
```rust
let elevation: Elevation = paris.calculate_elevation_to(&moscow);
// elevation.positive — gain in meters
// elevation.negative — loss in meters
```
- **check if inside a bounding box**:
```rust
let area = Area { min_latitude: 54.7, max_latitude: 56.7,
min_longitude: 36.6, max_longitude: 38.6 };
let is_in: bool = location.is_in_area(&area);
```
- **check if inside a radius** (km):
```rust
let is_in: bool = location.is_in_radius(¢er, &70.0);
```
---
## trace
`Trace::new` ingests raw GPS locations and precomputes everything in one shot:
- Douglas-Peucker simplification (for traces > 1 000 points, ε = 15 m)
- Cumulative distances
- Denoised cumulative elevation gain / loss (median smoothing + hysteresis)
- Smoothed slope at each point
- Peaks and valleys (AMPD algorithm with prominence filter)
- Qualifying climb segments (Garmin-style thresholds)
A `Trace` is never empty — construction fails with `TraceError::EmptyTrace`
if `locations` is empty, so every other method can assume at least one point.
```rust
let trace: Result<Trace, TraceError> = Trace::new(&locations);
// or via the convenience wrapper:
let trace: Result<Trace, TraceError> = build_trace(&locations);
```
### precomputed fields (accessed via methods)
```rust
trace.locations() // &[Location] — simplified working set
trace.cumulative_distances() // &[f64] — km from start, [0] == 0.0
trace.cumulative_elevation_gains() // &[f64] — denoised gain in meters
trace.cumulative_elevation_losses() // &[f64] — denoised loss in meters
trace.slopes() // &[f64] — % grade at each point
trace.peaks() // &[usize] — indices of detected peaks
trace.valleys() // &[usize] — indices of detected valleys
trace.climbs() // &[ClimbStats] — qualifying climb segments
trace.total_distance() // f64 — total distance in km
trace.total_elevation_gain() // f64 — total denoised gain in meters
trace.total_elevation_loss() // f64 — total denoised loss in meters
trace.area() // &Area — bounding box
trace.elevation() // &Elevation — raw positive/negative totals
```
### methods
- **total length** (km):
```rust
let length: f64 = trace.length(); // alias for total_distance
```
- **location at a cumulative distance** (km):
```rust
let loc: Option<&Location> = trace.point_at_distance(42.0);
```
- **index at a cumulative distance** (binary search):
```rust
let idx: usize = trace.index_at_distance(42.0);
```
- **slice between two distance marks** (km, both ends inclusive):
```rust
let section: Option<&[Location]> = trace.slice_between_distances(10.0, 50.0);
```
- **closest location to a point** (early-stop heuristic for loop courses):
```rust
let (loc, idx, dist_km) = trace.find_closest_point(&target).unwrap();
// start search from a known index (e.g. to handle loop courses):
let result = trace.find_closest_point_from(&target, start_from);
```
- **bounding box** (never fails — a trace always has at least one point):
```rust
let area: &Area = trace.area();
```
- **sub-section by index range** (inclusive):
```rust
let section: Result<&[Location], TraceError> = trace.get_section(start_index, end_index);
```
### climb stats
```rust
pub struct ClimbStats {
pub start_index: usize, // valley index in trace.locations
pub end_index: usize, // summit index in trace.locations
pub start_dist_km: f64,
pub climb_dist_km: f64,
pub elevation_gain: f64, // meters
pub summit_elev: f64, // meters
pub avg_gradient: f64, // %
}
```
Climbs are qualified using Garmin Climb Pro thresholds:
`distance ≥ 500 m`, `average gradient ≥ 3 %`, `distance × gradient > 3 500 m·%`
---
## GPX parsing
Parse a `.gpx` file from raw bytes — no XML dependency, byte-scanning only.
```rust
use navigo::gpx::{parse_trace_points, parse_waypoints, parse_metadata};
let bytes = std::fs::read("route.gpx").unwrap();
// Extract track points as Vec<Location>
let locations = parse_trace_points(&bytes);
// Extract <wpt> elements as Vec<Waypoint>
let waypoints = parse_waypoints(&bytes);
// Extract <metadata> fields
let meta = parse_metadata(&bytes);
// meta.name → Option<String>
// meta.description → Option<String>
```
---
## Waypoints
```rust
pub struct Waypoint {
pub latitude: f64,
pub longitude: f64,
pub elevation: Option<f64>,
pub name: String,
pub description: Option<String>,
pub comment: Option<String>,
pub symbol: Option<String>,
pub wpt_type: Option<String>, // e.g. "Start", "LifeBase", "TimeBarrier"
pub time: Option<i64>, // Unix timestamp (seconds)
pub stop_duration: Option<u32>, // planned stop at this point (seconds)
}
```
Boundary classification:
```rust
waypoint.is_section_boundary(); // true for any waypoint with a non-null type
waypoint.is_stage_boundary(); // true only for Start / LifeBase / Arrival
```
---
## Pace model
### Minetti 2002
```rust
use navigo::minetti::{cmet, pace_factor, CMET_FLAT};
let cost = cmet(0.10); // metabolic cost at +10% grade (J/(kg·m))
let factor = pace_factor(0.10); // relative speed factor vs flat (= cmet/CMET_FLAT)
```
Domain: slope in `[-0.45, 0.45]` (clamped beyond).
### Fatigue, circadian & weather
```rust
use navigo::pace_model::{
fatigue_factor, circadian_factor, WeatherLookup, WeatherConditions,
K_FATIGUE, DEFAULT_BASE_PACE_S_PER_KM, DEFAULT_LIFE_BASE_STOP_S,
};
let fatigue = fatigue_factor(d_eff_km, k_fatigue); // exponential decay (≥ 1.0)
let circadian = circadian_factor(unix_time_s); // cosine, −15% at 03:30 UTC
// WeatherConditions fields:
// temperature_c: °C
// humidity_pct: 0–100
// wind_kmh: km/h
// precip_prob_pct: 0–100
let weather = WeatherLookup::empty();
// or with per-checkpoint data:
let weather = WeatherLookup::new(
vec!["La Mongie".to_string()],
vec![WeatherConditions { temperature_c: 5.0, humidity_pct: 80.0, wind_kmh: 30.0, precip_prob_pct: 40.0 }],
);
let factor = weather.factor_for("La Mongie"); // combined thermal + wind + precip factor
```
Useful constants:
| `K_FATIGUE` | `0.002` | Default fatigue coefficient |
| `DEFAULT_BASE_PACE_S_PER_KM` | `500.0` | 8:20/km flat pace |
| `DEFAULT_LIFE_BASE_STOP_S` | `3600` | Default LifeBase stop (1 h) |
| `RECOVERY_LIFE_BASE` | `0.20` | 20 % effort reset at LifeBase |
---
## Route analysis
All three levels take a built `Trace` and a slice of `Waypoint`s derived from the same GPX file.
```rust
use navigo::gpx::{parse_trace_points, parse_waypoints};
use navigo::{build_trace, leg, section, stage, pace_model::WeatherLookup};
let bytes = std::fs::read("route.gpx").unwrap();
let trace = build_trace(&parse_trace_points(&bytes)).unwrap();
let waypoints = parse_waypoints(&bytes);
let weather = WeatherLookup::empty();
const BASE_PACE: f64 = 500.0; // s/km on flat terrain
const K_FATIGUE: f64 = 0.002;
const LIFE_BASE_STOP: u32 = 3600; // 1 h planned stop at LifeBase checkpoints
```
### Legs
One `LegStats` per consecutive pair of section-boundary waypoints.
```rust
let legs: Vec<leg::LegStats> = leg::compute_from_waypoints(&trace, &waypoints);
// legs[i].leg_id
// legs[i].section_idx
// legs[i].start_location / end_location (waypoint names)
// legs[i].total_distance_km
// legs[i].total_elevation_gain_m / total_elevation_loss_m
// legs[i].avg_slope / max_slope (% grade)
// legs[i].min_elevation / max_elevation (meters)
// legs[i].bearing (degrees from north)
// legs[i].difficulty (1–5, Naismith effort)
// legs[i].estimated_duration_s (Naismith rule, no fatigue)
```
### Sections
Sections are legs enriched with pace-model data (Minetti + fatigue + circadian + weather).
```rust
use navigo::{AnalysisOptions, section};
let options = AnalysisOptions::default()
.base_pace(500.0)
.fatigue(0.002)
.life_base_stop(3600);
let sections: Option<Vec<section::SectionStats>> =
section::compute_from_waypoints(&trace, &waypoints, &options);
// sections[i].section_id / stage_idx
// sections[i].start_location / end_location
// sections[i].total_distance_km
// sections[i].total_elevation_gain_m / total_elevation_loss_m
// sections[i].avg_slope / max_slope / min_elevation / max_elevation
// sections[i].start_time / end_time (Unix timestamps from waypoint <time>, or None)
// sections[i].bearing / difficulty
// sections[i].pace_factor — combined speed factor vs flat
// sections[i].estimated_duration_s — moving time + planned stop
// sections[i].max_completion_time — cutoff as Unix timestamp, or None
// sections[i].cutoff_ratio — estimated_duration / time_budget (< 1.0 = ok)
// sections[i].stop_duration — planned stop at end checkpoint (s), or None
```
### Stages
Stages group sections between Start / LifeBase / Arrival boundaries (TimeBarrier waypoints are skipped).
```rust
let stages: Option<Vec<stage::StageStats>> =
stage::compute_from_waypoints(&trace, &waypoints, &options);
// stages[i].stage_id
// stages[i].start_location / end_location
// stages[i].total_distance_km
// stages[i].total_elevation_gain_m / total_elevation_loss_m
// stages[i].avg_slope / max_slope / min_elevation / max_elevation
// stages[i].start_time / end_time
// stages[i].bearing / difficulty
// stages[i].pace_factor / estimated_duration_s
// stages[i].max_completion_time / cutoff_ratio / stop_duration
```
---
## Time utilities
```rust
use navigo::time::parse_iso8601_to_epoch;
// Supported formats: "2025-11-20T12:00:00Z", "2025-11-20T12:00:00+01:00"
let epoch: Result<i64, _> = parse_iso8601_to_epoch("2025-11-20T12:00:00Z");
```
---
## Live calibration
Recalibrate remaining ETAs mid-race given the actual elapsed time at a known position.
```rust
use navigo::calibration::{recalibrate_from_current, BoundaryKind};
use navigo::AnalysisOptions;
let options = AnalysisOptions::default()
.base_pace(500.0)
.fatigue(0.002)
.life_base_stop(0);
let result = recalibrate_from_current(
&trace, &waypoints, BoundaryKind::Section,
current_index, // trace point index snapped to current position
actual_elapsed_s,
&options,
);
if let Some(cal) = result {
cal.calibration_factor; // clamped to [0.5, 3.0]
cal.calibrated_base_pace_s_per_km; // adjusted flat pace
for eta in &cal.etas {
eta.id;
eta.remaining_duration_s;
eta.cumulative_remaining_s;
}
}
```
The factor is only applied when `predicted_so_far ≥ 300 s` to avoid noise from very short segments.
---
## WebAssembly
The library can be compiled to WASM for use in web applications via the `wasm` feature.
Prebuilt bindings are published to npm as [`@totorototo/navigo`](https://www.npmjs.com/package/@totorototo/navigo) — `npm install @totorototo/navigo`.
### how it works
All data lives in WASM linear memory. The JS side holds a thin pointer (`Trace`).
Only the boundaries cross the WASM↔JS membrane — scalars are free (registers), bulk arrays are copied once on demand.
```
buildTrace(Float64Array) ← one O(n) copy JS→WASM, null if no points
│
▼
Trace stays in WASM memory
│
├── trace.totalDistance → free (register)
├── trace.findClosestPoint() → free (scalars in/out)
├── trace.locationsFlat → one O(n) copy, cache it
└── trace.free() ← you must call this (no GC bridge)
```
### build
```bash
cargo install wasm-pack
wasm-pack build --target web -- --features wasm # ES modules — Vite, plain browser
wasm-pack build --target bundler -- --features wasm # webpack / Rollup
```
### usage
**From raw coordinates (`buildTrace`)**
```js
import init, { buildTrace } from "./navigo.js";
await init();
// build — one copy in, all computation in WASM
const pts = new Float64Array([
2.350987,
48.856667,
0, // lon, lat, alt
37.617634,
55.755787,
200,
]);
const trace = buildTrace(pts);
// → Trace, or null if pts carries no points
// scalar getters — free
trace.totalDistance; // number (km)
trace.totalElevationGain; // number (m)
trace.totalElevationLoss; // number (m)
trace.locationCount; // number
// array getters — copy once, then cache on the JS side
const locs = trace.locationsFlat; // Float64Array [lon,lat,alt,…]
const dists = trace.cumulativeDistances; // Float64Array (km)
const gains = trace.cumulativeElevationGains; // Float64Array (m)
const losses = trace.cumulativeElevationLosses; // Float64Array (m)
const slopes = trace.slopes; // Float64Array (%)
const peaks = trace.peaks; // Uint32Array (indices)
const valleys = trace.valleys; // Uint32Array (indices)
// query methods — scalars in, one small object out
trace.pointAtDistance(42.0);
trace.indexAtDistance(42.0);
// → number
trace.findClosestPoint(lon, lat, alt);
trace.findClosestPointFrom(lon, lat, alt, lastIndex);
// → same shape | undefined (use on live-tracking loops)
trace.sliceBetweenDistances(10.0, 50.0);
trace.getSection(startIndex, endIndex);
// → Float64Array [lon,lat,alt,…] (throws on out-of-bounds / invalid range)
trace.area();
// → { minLongitude, maxLongitude, minLatitude, maxLatitude }
trace.elevation();
// → { positive, negative } (raw, non-denoised)
trace.climbs();
// → [{ startIndex, endIndex, startDistKm, climbDistKm,
// elevationGain, summitElev, avgGradient }, …]
// always release when done — Rust allocator has no GC bridge
trace.free();
```
**From a GPX file (`parseGpx` / `trace.analyze()` / `analyzeGpx`)**
```js
import init, { parseGpx, analyzeGpx } from "./navigo.js";
await init();
const bytes = new Uint8Array(
await fetch("/route.gpx").then((r) => r.arrayBuffer()),
);
// Parse once — track-points, waypoints and metadata are all stored on the
// returned Trace, so nothing needs to be re-sent for the steps below.
const trace = parseGpx(bytes);
const options = { basePaceSPerKm: 500, kFatigue: 0.002, lifeBaseStopS: 3600 };
// Race analysis from the trace you already have — no bytes cross the
// boundary again, and the expensive trace computation isn't repeated.
const analysis = trace.analyze(options);
// → {
// waypoints: [{ latitude, longitude, elevation, name, wptType, time, … }],
// legs: [{ totalDistanceKm, totalElevationGainM, bearing, difficulty, … }],
// sections: [{ …leg fields, paceFactor, maxCompletionTime, cutoffRatio, … }],
// stages: [{ …same, grouped by Start/LifeBase/Arrival }],
// metadata: { name, description },
// }
// or null on malformed options
// Or, if you just want the JSON in one call and don't need the Trace handle:
const full = analyzeGpx(bytes, options);
// → { trace: { totalDistanceKm, totalElevationGainM, … }, ...analysis }
// or null on parse failure
```
**Live recalibration (`trace.recalibrate()`)**
Once the race clock has started and the runner has a GPS fix, correct the
static `.analyze()` prediction against actual progress — see
[Live calibration](#live-calibration) above for the underlying model.
```js
const currentIndex = trace.findClosestPoint(lon, lat, alt)?.index;
const recalibration = trace.recalibrate({
basePaceSPerKm: 500,
kFatigue: 0.002,
lifeBaseStopS: 3600,
currentIndex,
actualElapsedS: 5400, // real seconds since race start
});
// → {
// sections: { calibrationFactor, calibratedBasePaceSPerKm,
// predictedSoFarS, actualElapsedS,
// }
// or null on malformed options
//
// `sections` and `stages` solve independent calibration factors — each
// re-predicts at its own boundary granularity, with its own per-range
// weather lookup. Either is null when that boundary kind has fewer than
// 2 typed waypoints.
trace.free();
```
### memory management
`Trace` lives in WASM linear memory. The JS object is just a pointer — Rust cannot reclaim it when the JS variable is GC'd. Always call `.free()`, or register a `FinalizationRegistry`:
```js
const registry = new FinalizationRegistry((t) => t.free());
const trace = buildTrace(pts);
registry.register(trace, trace);
```
---
## license
[MIT](LICENSE)