To get good 2D and 2.5D (digital elevation model) results, you will require 42% overlap and sidelap for an equivalent 70% overlap and sidelap. To get good 3D results, you will require 68% overlap and sidelap for an equivalent 83% overlap and sidelap. OpenDroneMap will generate a calibration file called cameras.json that then can be imported to be used to calibrate another flight that is more efficiently flown.Īlternatively, the following experimental method can be applied: fly with much lower overlap, but two crossgrid flights (sometimes called crosshatch) separated by 20° with a 5° forward facing camera.Ĭrossgrid overlap percentages can be lower than parallel flights. To mitigate this effect, there are a few options but the simplest are as follows: fly two patterns separated by 20°, and rather than having a nadir (straight down pointing) camera, use one that tilts forward by 5°.Īs this approach to flying can be take longer than typical flights, a pilot or team can fly a small area using the above approach. James and Robson (2014) in their paper Mitigating systematic error in topographic models derived from UAV and ground‐based image networks address how to minimize the distortion from self-calibration.īowling effect on point cloud over 13,000+ image dataset collected by World Bank Tanzania over the flood prone Msimbasi Basin, Dar es Salaam, Tanzania. Automatic or self calibration is possible and desirable with drone flights, but depending on the flight pattern, automatic calibration may not remove all distortion from the resulting products. Temperature changes, vibrations, focus, and other factors can affect the derived parameters with substantial effects on resulting data. mesh-size should be increased to 300000-600000 and -mesh-octree-depth should be increased to 10-11 in urban areas to recreate better buildings / roofs.Ĭamera calibration is a special challenge with commodity cameras. texturing-data-term should be set to area in forest areas. Using this flag will increase runtime and memory usage, but may produce sharper results. ignore-gsd is a flag that instructs ODM to skip certain memory and speed optimizations that directly affect the orthophoto. Decrease this value for a higher resolution result. orthophoto-resolution is the resolution of the orthophoto in cm/pixel.
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