What is an orthomosaic map and why would you need one?

Are you learning about drones and aerial photography and filming? Then you’re sure to come across many new terms and phrases related to different drone processes. One of these is ‘orthomosaic’. And, here’s what you need to know...

An orthomosaic photo (also known as an orthophoto or orthoimage) refers to an aerial photograph that has been geometrically corrected so that the scale is uniform i.e. with the same lack of distortion as a map.

Things to know about orthoimagery and orthomosaic maps

1. Orthomosaic maps are made up of a series of individual photos which have been matched up via drone software so that they form a new composite image, consisting of all the smaller ones. 

2. These images have been adjusted for topographic relief, lens distortion, and camera tilt.

3. Because orthomosaic maps offer an accurate representation of the land, they can be used to measure true distances.

4. The process of photogrammetry refers the science of obtaining reliable measurements from photographs and digital imagery. Photogrammetry results in orthoimage maps, symbolic maps, GIS layers, or 3D models of real-world objects or scenes.

5. The process: In aerial photogrammetry, the sensor onboard a drone is usually pointed vertically down toward the ground – this is referred to as vertical or nadir imagery. Multiple overlapping images are collected as the sensor flies along a specified flight path. These images are processed and ‘stitched’ together to produce orthomosaic maps. The collected orthoimages are geometrically corrected so that the resulting image has the geometric integrity of a map. To do this, you need imagery with known sensor positions, attitudes, and a calibrated geometric model for the sensor along with a digital terrain model.

6. More than being a great to-scale, high resolution map of specified terrain, the meta-information within an orthomosaic map allows for point clouds, volumetrics, NDVI, and 3D tours. This means the map offers businesses across various industries an exciting business tool. For example, orthomosaic maps allow clients to virtually tour working sites or real estate offerings, and give business owners the ability to generate site progress reports over time, deliver up-to-date maps of agricultural land, and conduct inspections over difficult or dangerous terrain.

When it comes to drones, there is so much to learn and their capabilities and applications are expanding by the day. Want to use of drones in your business or learn how aerial mapping and surveying services can enhance your productivity in 2018? Talk to us! As drone experts, we work with professional organisations across various industries and environments, offering them drone-related commercial services and turnkey drone surveying and mapping solutions.

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