Photoshop

Merge Panorama

Copy all layers to new layers
select all copies, right click > convert to smart object
select smart object, go to layer > smart objects > stack mode > median
rename to foreground & hide
hide all but one layer
select one layer, add layer mask, select white box on this layer
chose brush, select black color, mask out foreground (if it doesn’t show up, make sure all layers are hidden but this one)
control + alt click mask and drag to next layer, repeat for all non-foreground layers
unhide all non foreground layers
select all
edit > auto align layers with defaults
right click each mask & delete
select all layers > right click > convert to smart object, name ‘sky’
select new smart object, layer > smart objects > stack mode > median


unhide foreground
add new layer mask to foreground
brush with black, paint out sky.
flatten, save