An orthophoto is an image of the earth's surface that eliminates any distortion that occurs at the time of shooting as a result of the slope and terrain.
Orthophoto maps are made from aerial photographs with specialized computer programs designed for this purpose.
Orthophoto maps are made according to a certain map nomenclature.
In Latvia, orthophoto maps are prepared in the Latvian coordinate system LKS-92 TM according to the TKS-93 map sheet division (scale 1:10 000 map sheet corresponds to 5 x 5 kilometers in nature).
Orthophoto maps are prepared for the whole territory of Latvia in TIFF format in the scale of 1:10 000, but for separate territories - for cities and densely populated areas - in the scale of 1: 2 000 or 1: 1 000.
After the restoration of independence, aerial photography of the entire territory of the country at a scale of 1:10 000 was performed five times.
High-resolution orthophoto maps are prepared with the following resolution:
- M 1: 2,000 (resolution 0.15 - 0.20 m)
- M 1: 1,000 (resolution 0.10 m)
Aerial photography for this purpose is performed at an altitude of 1,500 - 2,000 m.
Orthophoto maps are prepared in the Latvian geodetic coordinate system LKS-92 TM according to the division of TKS-93 map sheets and include an area of 1 x 1 kilometer.
Aerial photography at a scale of 1: 2,000 was carried out between 1994 and 2005, initially with analog cameras, but from 2002 also with digital cameras.