Show HN: Every mountain, building and tree shadow mapped for any date and time

Original Article ↗ Hacker News Discussion ↗

Overall Reception

  • Many commenters find the tool impressive, fast, and visually striking, calling it useful, even “sublime” and “moving.”
  • Others emphasize that it’s an approximation and warn against over‑trusting it, especially in poorly mapped areas.

Practical Use Cases

  • Planning shade/sun:
    • Where to park cars to stay cool in summer.
    • Picking shaded or sunny walking routes (summer vs winter).
    • Choosing stadium seats, lunch spots, or park benches.
  • Real estate and home use:
    • Evaluating sun exposure for house hunting and rentals.
    • Showing how new high‑rises block sun for existing homes.
    • Placing gardens, planter beds, and outdoor spaces.
  • Solar and energy:
    • Rough estimation of solar panel viability and shading over seasons.
    • Interest in RV/boondocking solar generation planning.
  • Photography:
    • Planning light/shadow for outdoor shots and “Manhattanhenge”-style events.

Accuracy, Coverage, and Data Quality

  • Mixed reports:
    • Some users see tree lines, forests, and building shadows matching reality very well, including historical vegetation.
    • Others report:
      • Missing large forests or most local trees.
      • Entire wooded areas or buildings absent or wrong.
      • Excessive shadows from small hills, or steep terrain timing errors.
  • “Every mountain, building and tree” is viewed as marketing overreach; many highlight incomplete coverage, especially outside well‑mapped regions.
  • Premium vs free:
    • Premium (about $2) reportedly adds more detailed tree and shadow data for some, but others still find inaccuracies.
    • Several want a way to trial full data on familiar locations before paying.
  • Data sources mentioned: OpenStreetMap (limited building heights), public LiDAR, “indirect” and crowdsourced sources; roof shapes are noted as missing.

Technical and UX Notes

  • Shadows from terrain work even where no buildings/trees are mapped.
  • Features praised: annual sunlight/hours-in-sun layers, ability to scrub date/time, canopy vs “below canopy” modes.
  • Issues raised:
    • Shadows vanish at lower zoom levels when buildings aren’t rendered.
    • DST handling looks confusing; local-time behavior is debated.
    • No visible “accuracy index” or data-age indicator by region.

Related Tools and Ideas

  • Several related apps and sites are mentioned for sun angles, shadow mapping, and solar planning.
  • Desired extensions include: shade-aware routing, perspective/visibility views, WISP/antenna planning, and crowd-sourced photogrammetry to refine heights.