What causes "Earth has no PDS raster" in louis-e/arnis?

Use the Earth-specific elevation provider (e.g. the fixed-tile/SRTM path) instead of PlanetaryDem when body is Earth.

Earth has no PDS raster

Error message

Earth has no PDS raster

What it means

tile_name returns the PDS raster filename for a given celestial body's elevation band. Only Mars (banded files) and the Moon (single ldem_128.img file) have PDS rasters; Earth elevation is handled by a different provider path, so reaching tile_name with CelestialBody::Earth is a logic error and the code asserts this with unreachable!. Hitting this panic means Earth data was routed into the planetary (PDS) DEM pipeline.

Source

Thrown at src/elevation/providers/planetary.rs:97

        (self.lon_span * self.ppd as f64) as usize
    }

    /// File name for the tile whose band starts at `(lat_band_min, lon_band_min)`.
    fn tile_name(&self, body: CelestialBody, lat_band_min: f64, lon_band_min: f64) -> String {
        let lat_band_max = lat_band_min + self.lat_span;
        match body {
            // megt{max_lat}{n|s}{lon:03}hb.img, label is MAXIMUM_LATITUDE.
            CelestialBody::Mars => {
                let hemi = if lat_band_max >= 0.0 { 'n' } else { 's' };
                format!(
                    "megt{:02}{hemi}{:03}hb.img",
                    lat_band_max.abs() as i32,
                    lon_band_min as i32
                )
            }
            // One global file, so the band arguments are always the full globe.
            CelestialBody::Moon => "ldem_128.img".to_string(),
            CelestialBody::Earth => unreachable!("Earth has no PDS raster"),
        }
    }
}

pub struct PlanetaryDem {
    pub body: CelestialBody,
}

impl ElevationProvider for PlanetaryDem {
    fn name(&self) -> &'static str {
        match self.body {
            CelestialBody::Moon => "lola",
            CelestialBody::Mars => "mola",
            CelestialBody::Earth => "planetary",
        }
    }

    fn coverage_bboxes(&self) -> Option<Vec<LLBBox>> {

View on GitHub (pinned to 34048924d9)

Solutions

Use the Earth-specific elevation provider (e.g. the fixed-tile/SRTM path) instead of PlanetaryDem when body is Earth.
Add an explicit guard at PlanetaryDem construction that rejects CelestialBody::Earth with a clear error, so the failure surfaces at setup rather than mid-fetch.
Fix the body/provider dispatch so Earth requests never route to the PDS pipeline.

Example fix

// before
let dem = PlanetaryDem { body: CelestialBody::Earth };
dem.fetch_row(...); // panics: unreachable
// after
match body {
    CelestialBody::Earth => earth_provider.fetch(...),
    CelestialBody::Mars | CelestialBody::Moon => PlanetaryDem { body }.fetch_row(...),
}

Defensive patterns

Strategy: validation

Validate before calling

if dem.body === 'Earth') throw new Error('PlanetaryDem does not support Earth; use the Earth elevation provider');

Type guard

fn is_pds_supported(body: &CelestialBody) -> bool {
    matches!(body, CelestialBody::Mars | CelestialBody::Moon)
}

Try / catch

// Rust panic; guard upstream instead
assert!(is_pds_supported(&dem.body), "PlanetaryDem requires Mars or Moon");
let row = dem.fetch_row(...);

Prevention

Route Earth requests to the Earth elevation provider at the dispatch layer
Reject unsupported bodies at provider construction, not at fetch time
Document which CelestialBody variants each provider supports

When it happens

Trigger: Calling fetch_row on a PlanetaryDem whose body is CelestialBody::Earth; constructing a PlanetaryDem with body = Earth and then invoking any fetch path that resolves a PDS tile name.

Common situations: Config or body-selection code defaulting to Earth but instantiating the planetary provider instead of the Earth provider; a body enum parsed from user input ('earth') reaching the wrong provider; a dispatch table that lists Earth as supported for planetary DEMs.

Related errors

AI-assisted analysis of louis-e/arnis@34048924d9 (2026-09-03). Data as JSON: /api/errors/ec2bacb5a879cb68. Report an issue: GitHub.