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Technical

Orthophoto

A scaled, geometrically corrected aerial photograph. Used in cadastre, zoning planning, and parcel boundary verification; similar to Google Maps satellite view.

An ortophoto is an aerial image that has been orthorectified — corrected for surface topography, camera tilt and lens distortion — to make it scale-uniform. Every pixel is at its correct geographical coordinate; it can be overlaid on a map and used confidently for distance/area measurements.

Difference from a standard aerial photo: in a normal photo, centre-to-edge scale varies (e.g. tall buildings appear tilted); in an ortophoto, all pixels are at the same scale, as if viewed straight down. This correction uses a Digital Surface Model (DSM) or Digital Terrain Model (DTM).

In Türkiye, TKGM and the General Directorate of Mapping produce ortophotos. Common datasets: national ortophotos at 30 cm resolution, provincial 10-20 cm resolution, drone-based 2-5 cm resolution. TKGM MEGSİS has an ortophoto layer with open access in some provinces.

Use cases: cadastre updating (22/a renewal), zoning enforcement (unauthorised building detection), urban renewal analysis, drone-based property marketing, parcel-over-structure research. Drozero users can enable the ortophoto map layer and visually verify structures on a parcel.

Examples

  • 1.A real estate agent views the actual structure on the parcel in the ortophoto, compares it to the permit, and identifies **unauthorised building risk**.
  • 2.The municipal technical team uses a 5 cm-resolution drone ortophoto to map all illegal construction over the past 6 months at once.
  • 3.A Drozero user overlays a drone-captured ortophoto layer on the parcel map and visually flags boundary violations in the garden.

Frequently Asked Questions

What's the difference between an ortophoto and satellite imagery?expand_more
**Satellite imagery** is captured from space (Sentinel, Landsat, Pleiades); typical resolution 30 cm – 10 m. **Ortophotos** are usually captured from aircraft or drones; 2-30 cm resolution. Ortophotos give higher detail, satellites cover wider areas. Google Earth mixes them: ortophotos in city centres, satellite in rural areas.
Are drone ortophotos legally valid?expand_more
If produced through a professional **photogrammetry** process (control points, calibrated camera, DSM) by a qualified engineer, they can serve as technical reports. BÖHHBÜY certification is required. Official cadastre processes require TKGM-certified ortophotos. The drone operator must have SHGM flight authorisation.
Where can I obtain ortophotos?expand_more
**TKGM MEGSİS** is free in some provinces; the **General Directorate of Mapping** (hgm.msb.gov.tr) has national coverage; local municipalities' GIS portals (e.g. İBB City Map) offer detail. Commercial sources: Nearmap, EOMAP, local drone companies. Ortophotos in Drozero's map layers are sourced from TKGM.
What ortophoto resolution is appropriate?expand_more
Depends on purpose: **Overview / location verification** — 30 cm is enough; **building detection / zoning audit** — 10-15 cm; **precise survey / parcel boundary** — 5 cm or below. High resolution adds huge file size (1 km² ortophoto at 5 cm is ~4 GB); served as 'pyramid' format for browser display.

Related Terms

GIS (Geographic Information System)Coordinate SystemPafta (Cadastral Sheet)Polygon

Sources

  • • Large-Scale Map and Map Information Production Regulation (BÖHHBÜY)
  • • TKGM Ortophoto Production Technical Specification
  • • ISPRS - International Society for Photogrammetry and Remote Sensing Standards

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Last updated: 2026-04-24