MERN- Production of Digital Orthophotos

Aerial Photography and Aerotriangulation

Production of Digital Orthophotos

Remote Sensing

Topographic, General, and Administrative Mapping

Geodetics and GPS Technology

Public Land Planning

Delegation of Public Land Management

Management of Land Rights

Development and Operation of Computerized Systems

Géoboutique Québec

Leasing Public Land


Production of Digital Orthophotos



Digital orthophotographs are a source of geographic information that can satisfy a multitude of land-management needs. Since orthophotographs are produced with the same mathematical rigor as topographic maps, they enable users to carry out their own interpretation of terrestrial phenomena, in addition to providing them with the means for measuring coordinates and distances.

The Department has been producing orthophotographs for 10 years. Moreover, the Department has developed sound expertise in playing a key role during special projects for managing risks related to landslides and flooding. This expertise in orthophotograph production and aerotriangulation, which is made available to public-sector agencies and departments of the gouvernement du Québec, covers the following:

  • Defining the product appropriate to the customer's needs (scale, digitalization, digital elevation model, georeferencing, and digital exchange format);
  • Planning work;
  • Writing technical specifications;
  • Awarding and supervising contracts;
  • Quality control.

In 1992, the Department began orthophotograph production in order to improve quality control for the Base de données topographiques du Québec at the 1:20,000 scale. This was carried out using photographs at the 1:40,000 scale, digitized at high resolution. They were corrected and rectified with respect to the earth in order to eliminate in accuracy due to tilt displacement due to camera angle and image displacement due to relief. The parameters for calibrating the airborne camera, aerotriangulation coordinates, and digital elevation model are used to carry out orthorectification.

Nearly 4,000 orthophotos at the 1:40,000 scale (of 1 metre resolution), covering all the habited portion of Québec, are available.

Areas of Application

Halfway between a map and aerial photography, an orthophoto offers the detail and richness of an aerial photograph combined with the accuracy of a map. Since orthophotos are georeferenced, they can include geographic information or bring out topography, territory boundaries, and themes related to various sectors of activity.

Orthophotography can be used in a number of fields, including:

  • The environment;
  • Agriculture;
  • Transportation;
  • Forestry;
  • Civil engineering;
  • Urban planning.

The homogeneity and quality of work are provided for through the application of rigorous standards. Projects managed by Department are carried out by specialized Québec firms, many of which have already worked abroad, in particular in Africa, Central America, and South America.

The Department has significant expertise in producing digital orthophotos. This recognized know-how can be shared with any government concerned with optimally developing its territory.