Celestia Forums

I realize that the file"earth.png" uses the alpha channel as a specularity map, but where is the data for the land, I mean I know it's there, it shows up in Celestia, but not in photoshop. Is there a way to turn the land back on in photoshop, edit it, then switch back to transparency for those areas?

Whatever is in the Alpha channel is all there is.
I don't use Photoshop, so I don't know why it won't let you extract the Alpha channel. I usually work on the Alpha channel as a separate image and then merge it into the final PNG or DDS texture file.

Usually only water areas reflect light as if they were mirrors, so having specularity values for the land areas may not be very realistic.

A completely separate specularity texture is often used, especially for VTs. They let you get close enough to see sunlight reflecting off rivers.

I'm not a Photoshop user either but, in the Gimp, what I do is Filters -> Colors - Decompose, and choose decompose to RGBA layers, then save the alpha layer as, say, alpha.png. Then I delete the alpha layer from the decomposed image, and recompose the RGB layers. When I want to restore the alpha layer, I decompose to RGB once again, and recompose as RGBA, using "alpha.png" as the alpha layer.

It's not as bad as it sounds, once you get the hang of it. There may be an easier way, but I'm not aware of it. I'm sure Photoshop can do the same thing.

HTH,
Jonathan