Orthophotomap is obtained through an aerial photographic survey and the subsequent conversion of the aerial photographs from a gnomonic to an orthogonal projection by the efficient method of differential orthogonal photo conversion. It is characterized by the absence of distortions of land, uniform tone colors and a uniform scale for the entire area shown in the image.The quality of the orthophotomap is determined by spatial resolution (ang. GSD), which determines the size of the pixel in the field.
OPEGIEKA delivers orthophotomap in the following forms:
- true color - RGB - shows the actual color of visible light,
- monochrome - B/W - shows the colors in the shades of gray,
- CIR (Color InfraRed) - reveals the condition of plants,
- thermal - shows the distribution of the emission of thermal radiation,
- night - shows the distribution of artificial light in urban areas,
- aerial mosaic - features similar to orthophotomap, however, possible to be obtain in a shorter amount of time.
Digital Terrain Model
Digital Terrain Model is a numerical representation of the land surface, which consists of a structured set of selected surface points and interpolation algorithms to reproduce the shape of the land surface. Data source for DTM: direct surveying, cartographic materials, photogrammetric measurements, aerial laser scanning and radar interferometry. There are two most common types of NMT: regular in form of a rectangular grid of GRID points and irregular in form of a TIN triangle grid.
Digital Surface Model
NMT is a digital record of the formation of soil while DSM also takes into account the record of plant cover, buildings and civil engineering works. The model is based on a set of well-selected points of the area and the algorithms that enable to reproduce the area in any place.
In the process of creating models OPEGIEKA uses the following methods of data collection:
- cartography - processing of existing cartographic studies,
- field measurements - direct measurements with the use of total station or GPS device,
- LIDAR technology - aerial laser scanning,
- photogrammetric measurements - based on aerial and satellite photographs.