Function project_gnss 

pub fn project_gnss(
    positions: &[GnssPosition],
    network: &RailwayNetwork,
    config: &ProjectionConfig,
) -> Result<Vec<ProjectedPosition>>

Project GNSS positions onto railway network

Projects each GNSS position onto the nearest railway netelement, calculating the measure (distance along track) and perpendicular projection distance.

Algorithm

1. Find nearest netelement using R-tree spatial index
2. Project GNSS point onto netelement LineString geometry
3. Calculate measure from start of netelement
4. Calculate perpendicular distance from point to line
5. Emit warning if projection distance exceeds threshold

Arguments

• positions - Slice of GNSS positions with coordinates and timestamps
• network - Railway network with spatial index
• config - Projection configuration (warning threshold, CRS settings)

Returns

• Ok(Vec<ProjectedPosition>) - Successfully projected positions
• Err(ProjectionError) - If projection fails (invalid geometry, CRS mismatch, etc.)

Examples

use tp_core::{parse_gnss_csv, parse_network_geojson, RailwayNetwork};
use tp_core::{project_gnss, ProjectionConfig};

// Load data
let netelements = parse_network_geojson("network.geojson")?;
let network = RailwayNetwork::new(netelements)?;
let positions = parse_gnss_csv("gnss.csv", "EPSG:4326", "latitude", "longitude", "timestamp")?;

// Project with custom warning threshold
let config = ProjectionConfig {
    projection_distance_warning_threshold: 100.0,
    transform_crs: true,
    suppress_warnings: false,
};
let projected = project_gnss(&positions, &network, &config)?;

// Check projection quality
for pos in &projected {
    if pos.projection_distance_meters > 50.0 {
        println!("Warning: large projection distance for {}", pos.netelement_id);
    }
}

Performance

• O(n log m) where n = GNSS positions, m = netelements
• Spatial indexing enables efficient nearest-neighbor search
• Target: <10 seconds for 1000 positions × 50 netelements