This proceedure is use to map in texture or objects in sceneries, so I'm not sure why a lot of people havn't don't it ealier.
Some of Reflex's or Aerofly's old sceneries has funkie sky becuase taking
an equirectangular can be a challenge due to wind or sun glair.
Well..just having clouds on the sides and the overhead is all the same
color..looks wierd too.
Plus you'll notice swirl lines, dots, of paint brushe tools if the aurther
tried to make corrections using a paint air bursh.
This cures it.
Basically..you're just going make the sky's texture portion
transparent, then drop in different skies as a backdrop.
First set you display setting to 32bit or the highest quality as you can because the images that gets gernerate will render accordingly.
I use GIMP.
GIMP is a freeware, plus it allows me to work on mega pixels images.
I select" Layer"..then select transparent, then turn on ALPHA channel.
Then save that images under GIMP's (.xcf files) type.
Then i just start tracing the terrain's lines and cut out the sky.
I set the veiw at 200% to 400%. This way, it's into the details of the images.
After I complet doing that...I'll always have that same foreground
as a template..then drop in differnt skies as I want.
Once you get better..you can use GIMP to impose other images
into the pano as some of the sceneries, such as the versiouse versions
you'll see of the Diesterdorf scenery or the G-3.
After I render different skies. I just save that as .JPG files..then feed it into a cube the sphere converter to have a skybox to use in FMS,
Heli'x, Preflight, or Clearview.
I also went an extra step and put in little planets for the bottom
panel. I inverted the pano then resized it. Then clipped it to the
bottom panel to make up for the missing portions of Reflex's
or Aerofly's . You can't see it most of the time , but i thought it was
cool. Plus it blends the grass area closest to the camera if I do.
Here's what I'm saying.
The original pano with the sky painted out
The GIMP as .xcf file after sky cutted out and set to alpha for transparent.
a different sky
a different sky
A skyline of a city inserted.
a complete photolistic pano scenery done by layering
If you take your time, you'll be rewarded.. You don't have to do it all
in oneday or at one time.