Monday, 12 May 2008

'Textures'


The maps of Furaha are at present available in two forms: a line map showing coasts, and a pixel-based map showing elevation. Both were done in Matlab, allowing myriad different projections and many display options. The pixel-based one has 4320x2160 pixels, meaning it has a resolution of 5 minutes of arc. In the neighbourhood of the equator that's about 11 kilometres per pixel. Not bad, but not very detailed either.

Unfortunately, there's one thing such maps cannot do, and that is to show the planet as it looks from space. Height is one thing, but colour is another. NASA publishes great maps of what Earth looks like as seen with satellite imagery. What these show you is that seasons make a difference, which isn't too surprising, and also that deserts are yellowish and the rest of the land is green, varying from bright green to dark green and grayish green. Height is only important in that it is more likely than other regions to be either snow-white or desertlike in colour.

Others have found their ways to such data stores as well, to give their fictional worlds that realistic look. Some great examples can be found at Celestia, a program allowing you to zoom through space and have a look at realistic and real objects. At the Celestia Motherlode you will find objects made by users that are equally realistic but as unreal as the others are real.

How do they do it? You have to paint a 'texture', meaning a colour image of what the image of your planet would look like. The best way to do so is probably to 'borrow' bits of Earth texture from NASA, shift and rotate them, and paste them together to obtain a good result. That sounds easier than it is, and many hours of work go into a good texture. I have just started work on a Furaha texture. I decided that this was a good accasion to learn to use Photoshop anyway. My first experiences with it are frustrating: nothing works the way I want it do, and nothing is where I expect it to be. This is probably my punishment for not starting to use it many years and versions ago, when learning it was more or less manageable.

The good news is Celestia. At least that program, which is completely free (!), allows you to obtain a quick and rather good looking rendering of your texture. Generally you just hijack Earth's or Venus' texture and replace it with your own, and, voila, a realistic rendering. Earth is shown at the top of this post, and my first attempts at Furaha follow.



The golden sheen means that the 'texture' is just a monochromatic yellow rectangle. Still, you can see how Celestia makes land dull and oceans shiny, and uses the height map to good effects in that it helps form lighting and shading effects. The final image, below, shows an extremely rough Furaha image, with very coarse colours. The clouds make a big difference though, don't they ('borrowed' from Celestia's Earth map...). By the way, if you are surprised by the spelling, Celestia somehow figured out I am in the Netherlands, so it changed its language to Dutch, but with a distinctive Flemish spelling.


Oh yes, to do it right, I still have to figure out where to place deserts, and to that properly I need knowledge of climatology. Which I haven't really got, so it will have a be a hopefully reasonable guess...

1 comment:

eleazar said...

This isn't exactly a "proper knowledge of climatology", but this site: http://www.cix.co.uk/~morven/worldkit/climate.html

... provides the next best thing. I've found it very useful with my own project.