Drone surveying is much more of a process than taking a couple aerial photographs and calling it a day. In a job where being off by a few inches can have a huge impact on your work, it’s essential to make sure you get it right and your images can be scaled properly.
Creating orthomosaics is one of the most common solutions to ensure high image quality and remove any scaling challenges when used in appropriate situations.
Orthomosaic images are high-resolution aerial images taken from a drone and then stitched together with specialized software to create a high quality and distortion free map. The stitching process called orthorectification, removes the perspective from each image, to create consistency across the map while maintaining the original level of detail.
This imagery differs from standard aerial photography by using technology to correct camera tilt, perspective and lens distortion. This is what allows for the photos to be accurately scaled from image to image. You’ll still need to use standard drone land surveying techniques but this will make surveying measurements you can rely on for true distances.
A single orthophoto will not have much value on its own, as it will appear distorted. It’s important to note each photo is taken from a different perspective and must be orthorectified together to make the map consistent.
To make this process most efficient you will need to utilize an automated flight path and drone mapping software with orthomosaic capabilities.
Although orthomosaic maps have several benefits over typical aerial photos, an image of this quality may not be necessary for every job. The main advantages of orthomosaic maps are their scalability and consistency. One drawback is that this modeling style may require more close-up images which typically take more time.
While surveying is one of the more common sectors utilizing orthomosaics, others include farming, law enforcement, real estate and environmental conservation. Overall, orthomosaics have a wide range of applications useful for highly-detailed imagery and topographic precision.
(Source) Making Orthomosaics With Drones: Everything You Need To Know