Orthomosaics not Processing Correctly

[McKenzieBredemeyer]

I completed a flight plan in ArcGIS Flight offline in the forest and submitted it into SiteScan for processing, and even though the images were taken correctly over the entire mission area, the orthomosaic has large holes in it and there is a lot of distortion within the orthomosaic, not just around the edges where some distortion might be expected. I tired reprocessing the images multiple times, including uploading them to a brand-new project but nothing changed. This is only my fourth flight in ArcGIS Flight/SiteScan, but my three other flights were larger and more complicated missions and yet they processed fine. Does anyone have any insights and/or ways to combat in the future to avoid re-flights? SiteScan version 4.210.2, ArcGIS Flight version 5.1, DJI Mavic 2 Pro drone, flight plan had terrain aware on and was completely offline and nothing weird happened during the flight. Even though this is only my fourth mission, I have been using this drone for the last year to take imagery and it rarely had issues with processing images to orthomosaics in other software like DroneDeploy.

[Pål_Herman_Sund]

Hi,

my 5 cents - you need to increase the overlap a lot (90/90) and possibly also do crosshatch flight. The "distortions" and holes are a result of poor underlying surface (re-)construction.  

[dozer]

Hi @McKenzieBredemeyer , agree with @Pål_Herman_Sund , my guess is insufficient overlap. Would you be open to sharing the processing report here? It seems like some images were discarded especially in the areas with gaps in the ortho. Areas with tall trees and other elevated features are especially prone to this, as the target features (like the tops of trees) are much closer to the sensor than the ground is.

Usually increasing the overlap and/or flying at a higher elevation can improve that as it helps add redundancy in the dataset for tall features. 

Do you recall if any defaults were changed when preparing the flight plan in ArcGIS Flight? What was the overlap/sidelap set to, and at what height were you flying above the terrain? You could check these numbers by opening ArcGIS Flight, opening the "Refly" list of flight plans and browsing to this mission's flight plan.

[McKenzieBredemeyer]

All the defaults were kept the same for this area survey, except for setting the flight height to 400 ft, the departure/return height to 400 ft, terrain aware was turned on, and I set the camera to be the Mavic 2 Pro camera. Looks like the overlap was at 70% and sidelap was at 65% as the defaults.

[Pål_Herman_Sund]

In heavily vegetated areas I think even 90/90 in overlap has been mentioned. There seems to be quite correlation between "poor overlap" (2-4 images) in the overlap plot from the report and a poor/no result in your orto. You are certain all your images are "healthy" ? I leave it to @dozer for a better explanation - he is the expert 🙂 One thing @dozer - could be nice to have the "processing extent"/"mission area" included in the overlap plot?