Context Remote Aerial Imaging
& Terrain Modelling
& Terrain Modelling
An orthophoto or orthomosaic map is made by the compilation of numerous overlapping aerial images of an area of interest into a single distortion-free image such that it appears to have been taken from vertically above at an infinite distance.
Context Remote Aerial Imaging can deliver highly detailed, orthomosaic maps of your property, project or area of interest. Our mapping by drone is typically suited but not limited to smaller areas of about 100 hectares or less, where on-ground resolutions of several centimetres or better may be achieved, depending on flying height, camera resolution and other factors.
Orthomosaic mapping format examples
Terrain modelling is often a simple extension of orthophoto mapping since in many cases it just represents the extraction and presentation of addition information from the same captured imagery, as demonstrated in the picture sequence above. However in some cases where the terrain is steep and variable or greater elevation definition is required, or volume estimations or a 3D model are required, modified capture and processing techniques may be required to acquire adequate data and accuracy.
Typical situations where a detailed, high-resolution and accurate ortho-photo map would provide significant benefits are:
Aerial mapping provides an up-to-date map of your area of interest, photographically detailed and accurate according to the resolution of the images of which it consists, all of which have been geometrically ortho-corrected to adjust for topographic relief, lens distortion, and camera tilt. The map is of uniform scale in all horizontal directions and, provided that known points have been included that sufficiently define the spatial dimensions of the area, can be used to measure true distances within the accuracy achieved; the accurate location of these control points will also ensure the map can be correctly positioned in spatial relativity to the surrounding areas.
But why should it be necessary to produce a drone-derived orthomosaic when satellite imagery is readily available for most of the Earth's surface? Drone imagery typically may have a resolution of 20 mm or smaller, which is excellent for detecting objects not much bigger than that, whereas satellite imagery may be only able to resolve to 0.5 metre at best. So drone imagery is far superior when looking for fine detail in the images, but it is usually restricted to small areas no larger than a few hundred hectares at most and cannot easily or economically cover the vast areas that satellite imagery can. But then satellite imagery cannot compete with drone imagery for fine detail at the centimetre level. Refer to Drones vs Satellites: Competitive or Complementary? for a discussion of the issues involved.
Orthomosaics may serve as a base map onto which other map information can be overlaid, and are commonly used as a background image in Geographic Information Systems. They may also be used in CADD systems as an underlay and reference plane for the design of buildings, earthworks and many other types of installation and infrastructure, or they may simply be printed on large media for general reference and display.
Typical low-level orthomosaic site mapping
Archaeological & historical site mapping