Celestia Forums

Hi

I was looking through a topic in "Celestia Users", called "Post Your Celestia Pictures!" and on the very last page somewhere I caught the eye of some nice looking Gas Giants made by bdm

Bdm,

I was wondering if maybe you could tell me how you created those gas giants, maybe a mini tutorial? I am creating a new fictional system (but I am not going to spam it) and right now I need all the help with textures I can get.

Btw that pinch eliminator topic you found for me helped alot

Thanks

Mr Noob

Try this one.

http://dreamingsky.deviantart.com/art/C ... as-9776794

I have used some of the techniques from this tutorial. In particular, I have used the grass brush followed by motion blur to create some of the stripes in my gas giants.

The techniques shown here can be used to create more realistic gas giants than the one shown in the example. The first thing to remember is that gas giants tend to be symmetrical. So if you're creating a lighter band south of the equator you should also create a similar band a similar distance north of the equator. Gas giants also tend to have large, smooth bands rather than lots of lines on them.

The technique shown here is not intended for a wraparound texture. If you follow these techniques exactly for a Celestia texture, you will have a nasty seam at 180 degrees. To remove this seam, alternate the motion blur steps with a step to Offset the texture by 1/2 the width of the texture. The seam can also be removed efficiently by ending the motion blur steps with an offset followed by a motion blur for a much shorter distance, say 50 to 100.

To create gas giants, follow these steps:

Load the Jupiter texture into Photoshop. (The Jupiter texture shown here is reduced by 75% from the original.)



Create a New image with the same dimensions as the Jupiter texture, here 4096 x 2048. Call this "Gas Giant" or some other name.



Use the Clone Map tool to clone the white cloud band onto the new Gas Giant texture. The clone should go in precisely the right spot, so be sure to position the copy in exactly the same position as the original.

Use the Soft Round brush with a width of about 35 pixels. The soft round brush will create a feathered edge that will come in handy later.



Clone only the white band. It is helpful to magnify both textures so you can see what you are doing better. It is a good idea to go around the edges first with a smallish brush, then fill in the middle with a larger brush. This saves time.

Now use the Offset filter to check the edges for wraparound. We will be doing this fairly often. The offset should be 1/2 the width of the image. Also apply the offset to the Jupiter image.



Here we can see the image doesn't quite wrap properly: there is a sharp edge visible. Use the clone stamp tool to remove this.

Now duplicate the Gas Giant image. Flip canvas vertical, and then apply the Offset filter to offset it by 1/2 the width. This is necessary because Jupiter only has one decent white band but our Gas Giant will have two bands. These offset will hide the duplication better because the duplicated part of the textures will be hidden on opposite sides of the planet. If you have two Jupiter images you can use the white bands from each, which makes it unnecessary to clone the bands in this way.

Now use the Brush tool to paint temporary registration marks at the top and bottom of the Duplicate image. These registration marks MUST go to the top and bottom edges of the image. These are necessary because Photoshop 7 does not handle cut and paste properly with transparency and will paste the duplicate image in the middle of the target image, instead of offset as desired. These registration marks will be removed shortly.



In the Duplicate, Select All, and Copy. Then Paste it in the Gas Giant original. Now delete the duplicate image because it is no longer needed.

Select the layer that was just inserted. Use the Rectangular Marquee tool to select the registration marks one at a time along with a generous amount of space around them, and press Delete to remove them. Deselect the marquee.

Now go to the Layers menu and Merge Visible. The result is a layer with two white bands. Rename this layer "White Bands".

Create a new layer in the Gas Giant image. Move this layer to below the White Bands layer and call this layer "Equator".

Clone the equator of Jupiter onto the Equator layer. Again, place the clone in precisely the same position as the original. Use the Soft Round brush on a wide width. Any imperfections in the edge will be concealed by the white bands. Start just under the white bands and completely fill the space between them.



Here, the Great Red Spot intrudes into the image, making the bottom band look messy. This should be removed with the Clone Brush tool. Choose a suitable part of the Jupiter image and clone from that, covering the areas that need attention. Use the Soft Round brush for this because this brush blurs the edges well. When blending from a part of the image that is somewhat different to the original, set the Opacity to about 50% or so to hide the blending better.

The equator will be muted in the final image by having its opacity reduced. Therefore, it will need a background.

Create a new layer called Equator Background and place it below the Equator layer.

[step 7 screenshot was here - deleted it because it was no different to step 6] - bdm

Use the Eyedropper tool to choose a suitable colour from the Jupiter texture or the Gas Giant texture, or choose your own colour.

Select the Equator Background for editing.

Use the Rectangular Marquee tool to select the middle of the Equator Background layer. Go right to the left and right edges (this is important), and have the top and bottom edges lie somewhere underneath the white bands.

Use the Paint Bucket tool to fill inside the Rectangular Marquee. Deselect the Marquee.

The result will be a hidden background layer underneath the Equator layer.



We can then adjust the Opacity of the Equator layer to allow some of the Equator Background to show through. Doing this will make the equator clouds more subdued and allow the white cloud bands to stand out better.

Select the Equator layer and adjust the Opacity of this layer to 40%. The equatorial clouds will become more subdued.

Now we need some polar clouds.

Create a new layer called "Poles" and place it below the White Bands layer.

Clone both poles onto this layer. Starting at the poles, go about two-thirds of the way towards the white band layer. After cloning, offset the Jupiter source texture and the Gas Giant image by half the width, and check the middle for mismatched cloning. Clean it up if necessary.



Create another layer under the Poles layer and call it Poles Background.

Select the Poles Background layer. Use the marquee tool to select the part of the image that is not covered by the poles. Go right to the left and right edges. Then, select inverse to select both poles.

Choose a bluish colour and use the Paint Bucket tool to paint the Poles Background layer around both poles.

Deselect the marquee.

Choose a Soft Round brush that is fairly large, and blur the edges of the blue rectangles. Use the offset tool in the usual way to ensure the edges of the blue polar rectangles wrap around smoothly.

Set the opacity of the Poles layer to a value around 85%. This will mute the poles a bit and give them a bluish hue.



Create a new layer at the bottom of the layer stack and call it Bands Background.

Choose a light buff hue and fill the whole layer with this colour.

Create another layer below the White Bands layer and call this Bands.

Set the Foreground colour to white or a light buff colour, and the Background colour to a darker buff colour.

Select one of the Grass brushes. Adjust the brush settings as follows: Shape dynamics - size jitter 50%, minimum diameter 10%, angle jitter 100%. Colour dynamics - Foreground / Background jitter 100%, Hue jitter 15%.

Paint with the Grass brush in the blank bands between the White Bands and the Poles.



Use the Motion Blur filter with an angle of 0 and distance of 999.

Offset the image right by half the width of the image.

In the Brush settings, reduce the Foreground / Background jitter to 50%.

Repaint the band with the brush, concentrating the painting in the center of the band.

Use the Motion Blur filter with an angle of 0 and distance of 999.

Offset the image right by half the width of the image.

In the Brush settings, reduce the Angle jitter to 0% and the Foreground / Background jitter to 25%.

Repaint the band with the brush, concentrating the painting in the center of the band.

Use the Motion Blur filter with an angle of 0 and distance of 999.

Offset the image right by half the width of the image.

Use the Motion Blur filter with an angle of 0 and distance of 100.



Apply the Distort > Ocean Ripple filter with a ripple size of 12 and a ripple magnitude of 3.

This is the finished texture (reduced in size 75%).



Planet with texture.



VARIATIONS

You do not need to follow these steps exactly for good results. Here are some variations to try:

* Instead of cloning the poles two-thirds of the way towards the white bands, you can go all the way towards the white bands, clean up the result and skip the rest of the steps. The end result will look more like Jupiter.

* Adjusting the Hue and Saturation on the layers will produce planets of different colours.

* Instead of rendering the bands, one can paint in bands from another gas giant texture such as Saturn. After pasting in the bands, if they are too smooth one can do the Ocean Ripple on them as described above to make the edges look more turbulent.

The good bit of this method is the features of the planet are encoded as separate layers, which makes it easy to create a new planet just by modifying the layers.

In the tutorial, the Bands placed at the end are a bit bland, so I have substituted a band from a Saturn texture created by rthorvald on the Motherlode (here).

After cloning this band, I applied the Ocean Ripple distortion with a magnitude of 6.

Nice effort! Tx!

Bdm,

Thank you for making this tutorial. My understanding of how you make gas giants is complete. When I release my system lookout for a couple of these textures