This will alter the jupiter.jpg image to have transparent bands where light colors were.
The result will be called jupiter_transparent.png to be used as a cloud cover.
Get Gimp at http://gimp-win.sourceforge.net/
Download preliminary file gtk+-2.6.9-setup.zip and unzip it and run it.
Download gimp-2.2.9-i586-setup.zip and unzip it and run it.
Optionally, download gimp-help-2-0.9-setup.zip and unzip it and run it to get the help files.
Run Gimp 2 from the Windows XP menu start:all programs:Gimp 2
Use the menu File:open C:\Program Files\Celestia\textures\medres\jupiter.jpg
Use the menu File:save as.
Click the lower button Select file type (by extension).
Select PNG Image.
Click Save.
A window pops up, just hit OK with no changes.
You will see the new image in .png format.
Use the menu Layer:Transparency:Add Alpha Channel
Use the menu Layer:Transparency:Color to Alpha
A first window pops up for you to set which color you will draw with to mark transparent areas
There is an empty box labelled "From:" . Click in the box.
A second window pops up for you to set which color you will draw with to mark transparent areas
Click on the black area in the spectrum
Hit the OK button in this second window. The window disappears.
Hit the OK button in the remaining first window.
Use the menu Layer:Mask:Add Layer Mask
There is a list of check boxes. Check : Layer's Alpha Channel
Hit OK
Draw black areas with paint brush or spray can in the light bands of Jupiter as follows :
Use the window labeled The GIMP to select brush type and size of brush.
Brush : circle 19
Mode : Normal
Opacity : 100%
In the image of Jupiter, use your artistic talent to drag the clumsy mouse across the light bands
There are about 3 light colored bands to draw black over.
Use the menu Layer:Mask:Apply Layer Mask
Use the menu File:save
You are done.
Check the work by editing the extras files for Celestia .
(or as I do, maybe wrongly, edit the solarsys.ssc file to use the jupiter_transparent.png for clouds)
(If you will edit the solarsys.ssc, make a backup copy first, so you can restore the original)
"Jupiter" "Sol"
{
Texture "jupiter.jpg"
.
.
.
Atmosphere {
Height 300
Lower [ 0.7 0.6 0.5 ]
Upper [ 0.5 0.45 0.4 ]
Sky [ 0.8 0.8 0.5 ]
Sunset [ 1.0 0.6 0.2 ]
CloudHeight 2000
CloudSpeed 0
CloudMap "jupiter_transparent.png"
}
This uses the new texture for clouds :
C:\Program Files\Celestia\textures\medres\jupiter_transparent.png
Issues not resolved, yet :
1 The transparent image was not useable for Jupiters surface, only its clouds. When applied to its surface, it was opaque and light colored.
2 The image of Jupiter in Celestia with clouds got lighter than the original Jupiter without clouds.
Please post your comments on resolving these two issues.
Here is the cloudy Jupiter :
