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Author Topic: Median Orthomosaic Blending Mode  (Read 1341 times)

wgreenePIMS

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Median Orthomosaic Blending Mode
« on: August 16, 2021, 04:49:16 PM »
In most cases, the currently existing average and mosaic blending modes for orthomosaic generation work well. There are, however, circumstances where using a median blending mode instead of average would be incredibly useful. The example I've come across is creating drone-based orthomosaic maps where the water surface is present - if there's surface reflection / glare, then the mosaic blending mode produces very noisy results, because some images have extreme glare while others do not. The average blending mode solves the reflection problem, but introduces other issues, such as ghosting of objects that have poorly defined geometry, especially defoliated trees / shrubs, and the influence of especially bright spots or lighting changes on some image areas. A third blending mode, which simply uses the median pixel value for a given location, should help to solve some of those issues.  Median blending should be very easy to implement - it's already possible to accomplish in a GIS program by mosaicking exported orthophotos. It would save lots of time and effort to simply include it as an alternative blending mode within Metashape, though! If people have ideas about using Python scripting to accomplish this, that would work too  :).