Celestia Forums

Hi

I have been attempting overthe past few days to create rings for gas or ice giants. I just somehow end up with many problems. Before I get into detail I would just like to say that my graphics card is not the problem. I have Rassilons GC textures addon, he has rings, and they seem to show perfectly on my computer. Anyway the problem I have is that when I create my ring the black gaps in between the colours of the ring are not transparent. Other rings I have saw (excluding saturn's) don't have these black gaps, instead they are invisible. I have photoshop CS2 and i have learned already how to create gas giants and ice giants in it.

How I create my rings:
1) Opened photoshop CS2 and made a new 512x512 custom.
2) Set the background colour to black
3) Used the grass brush with 2 grey colours to paint the rings
4) Motion blured the picture then changed the image size to 512x32 (sometimes i do 1024x2)
5) Rotated the image angle 90 deg cw or ccw
6) Added an alpha channel (I get confused here)
7) Saved it in DDS format using photoshop nivida DDS format plugin
Used the texture in Celestia and this is where my problem started

If any of you guys can point me in the way via one of your ways of creating rings plz tell me because all the other tutorials i know of just don't work. I have followed their steps at least 5 times each checking back to make sure. I would be happy if someone could help me.

Mr Noob

It's the Alpha Channel which makes the Rings transparent.
By itself, it's an 8-bit grey-scale image which should be
black where you want the Rings to be transparent
white where you want them to be opaque, and
shades of grey where you want them to be translucent.
It should have the same orientation as the image in the RGB channels.

I usually use an ImageMagick command-line utility to merge Alpha Channel images into color images, something like this:


Someone else will have to tell you the Photoshop commands.

"Help Please :)" is a really uninformative and unhelpful title for a thread you know.

Did you save your RGBA texture as DXT1 or DXT3 format!??

I hope you used DXT3...

F.

edit 5:35 pm

I find it helpful to start with a transparent image. From there, we can create rings in a variety of ways.

One way is simply to paint the rings using the edge of a fuzzy brush, with the opacity set to 1% or 2% and drawing several times. Another is to paint the transparency onto the alpha channel mask instead.

After doing some painting, one filter that you would do well to try is the Noise filter. It allows you to create quick variations to the colours of the rings, or, if applied to the alpha channel mask, to the transparency. When using the Noise filter, set the variation to a low value between 1.5 and 3. I also recommend monochrome noise, particularly for the alpha channel.

Being able to control the transparency is important if you want to create gaps in the rings like the Huygens Gap or Keeler Gap in Saturn's rings. When I created these rings, I created the gap in the rings (see right) by starting with a transparent image and applying the brush everywhere except the place where I wanted the gap to be.

I think the best method is to paint the rings in the desired colours first, and then adjust the transparency using a mask. When done with the mask, be sure to blend the mask with the image.