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con quesa
03-03-2012, 05:41 AM
I'm trying to use GIMP to create a star chart for a fantasy world. Ideally close to what an imaginary observer might see if they walked outside and looked up at night on this world, but it's still a chart, rather than an attempt at a photorealistic image of the night sky (which is beyond my rather meagre abilities as an artist, anyway).

I tried simply making a black circular background and painting on white stars with the default circular brush in GIMP (different sizes for different magnitudes), but that looks rather boring. GIMP has a default brush called "Sparks", though, which has a pleasing yellow color to it and a star-looking shape that I'd like to use. Unfortunately, this brush ignores the foreground color, and always paints with that same shade of golden yellow, which isn't quite what I'm looking for. It also seems to have some built-in jitter - I can't make it paint just *one* star, it always puts a few down, as if I had turned on jitter. I would try editing the brush like in photoshop, but for one this brush in particular is read only ( I guess I can fix that by just coyping the brush file in the file system, but that seems cumbersome), and in any case none of the options seem to let me turn off what I need turned off anyway. What in GIMP controls whether a brush has its own color or uses the foreground color?

And of course, maybe I'm going about this the wrong way. If anyone has any other suggestions on how I might go about drawing semirealistic-looking stars on a black background, I'd love to hear them.

smoore
03-12-2012, 12:03 PM
I'm an amateur astronomer. The first method you used is what we expect to see. Do an GIS search for sky atlas 2000. Sometimes its white on black but generally the more detailed charts are black stars, green nebula, and light blue milky way on white. Star magnitudes are done by size. Putting in lines for the constellations makes it more interesting visually. This for example. (http://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/CaldwellStarChart.svg/1000px-CaldwellStarChart.svg.png). The next step would include more stylized constellations like Ptolemies star chart (http://josephsmithacademy.org/projects/images/ptol_map_n.jpg)

As far as using gimp learn to use layers. Do a background color for the chart. Make small drawings of stars with transparent backgrounds as separate images and copy and paste them onto a new layer above the background. Do a separate layer for constellation lines, and other details it will make it easier to edit in the long run. Save it as xcf format to maintain the layers but save as a png or jpg for display.