evildrganymede wrote:Source of the post Al the pictures of Elliptical galaxies that i've seen fade out into the surrounding space and don't have that edge.
In computer simulation, everything must have a border. Elliptical galaxy model is not an exception.
evildrganymede wrote:Source of the post Some do go to a bright point in the centre (e.g:), but often the central bright part is larger too - it doesn't just increase to a point with a gradient. e.g. IC 1101:
This is because how original hi-dynamic range photograph was converted to lo-dynamic range jpeg image. Telescopes takes photos using 16- to 24-bit depth CCD matrices, and astronomers uses all available data to make measurements. For public release, photos must be converted to 8-bit depth jpeg/bmp/png/whatever images to be able to display them on monitors. Some exposure conversion is used for this. Any photographer who is familiar with HDR photo knows this.
evildrganymede wrote:Source of the post Though granted I don't know how much of that is due to photo exposure. But they do just look 'artificial' to me in 0.9.8.0 at least - too mathematically defined.
Of course it is, because SE uses mathematically defined analytical model! It is called De Vaucouleurs profile and widely used by astronomers:
http://www.astro.rug.nl/~ahelmi/galaxies_course/class_VII-E/ellip-06.pdfCenter of the galaxy is indeed very point-like, because its surface brightness is thousands times larger than the brightness of a middle parts of the galaxy. While observing galaxies through telescope with an eye, you usually see only the central parts of the core, which looks like a fuzzy star.
evildrganymede wrote:Source of the post And also they never have any dust in them, which sometimes does happen (e.g. NGC 1316):
It is impossible to define in a pure analytical model. Such complex galaxies must be rendered in other way, which SE supports for spiral galaxies:
evildrganymede wrote:Source of the post As another option, could Ellipticals not be rendered the same way as the central bulges of spiral galaxies? Or even just with their own models and textures like spiral galaxies?
A custom sprite model for E galaxies can be created in the same way as for spiral galaxies, there is a
tutorial. But 99% of E galaxies have only bulge, so De Vaucouleurs model is enough for them; it also takes no memory and has 100 times faster rendering. Some of the first versions of SE had all E galaxies implemented using sprite models, but the result was not very good. The analytical De Vaucouleurs model is much more realistic.