Hi all,

here are some early rendering experiments of irregular galaxies with celestia.Sci that are based on the genuine Diffusion Limited Aggregation (DLA) algorithm.

I generated proper DLA dots (float) in 3D from fast C++ code. The resolution gets pretty good already after a very short running time during the initial code + data loading step.
E.g.
[click on images by all means + browser fullscreen!]

SMC:
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DDO 64
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Fridger

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Here is a "kingsize" image of NGC 4449 with pink HII regions activated

[click on image + browser fullscreen by all means!]


Fridger

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Some DLA news:

Here is another "kingsize" irregular galaxy, NGC 4449, with plenty of pink HII spots. The DLA algorithm is now fully embedded in the C++ code of .Sci.

There are many possible variations of the rendering appearance: notably sprite sizes and DLA growth & shape parameters & number of "particles"... Clearly, if viewed from a distance, irregular galaxies are not as smooth as nebulae. Like for the latest rendering of spiral galaxies, there is also a bluish "Big Blob layer, as may be easily inferred. The total number of involved DLA "particles" is 20000, a number that leads to no noticable delays during the initial loading process.

[click on image and use browser fullscreen by all means!]


Fridger

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Here is a brief status report about my progress of today:

1) I have decided to generate the DLA points for irregular galaxies in an external C++ application that will be part of the .Sci distribution. This way I can handle >= 50 000 particles without any noticeable delays!

2) I wrote another C++ command line application (txt2bin) that reads in the 50000 generated x-y-z points from a human readable text file, rescales the points to the maximal radius of sqrt( x^2 + y^2 + z^2) = sqrt(3 * 0.5^2) = sqrt(0.75), and writes out the rescaled data to a binary data file. Binary data files load lightening fast and take less than half the HD space, as you surely know!. I do this with five such binary template data files: irr0.dat .. irr4.dat, in order that the Irr displays look always different, notably for several Irr galaxies visible on ONE screen (e.g. DDO 64, see below) . As a result of the rescaling, the 4 "red selection triangles" indicate the proper size of the Irr galaxy pretty accurately! Here is an example (DDO 127)

[click on image and use browser fullscreen by all means!]


Look at the 4 red arrows! As shown at the bottom left, the framerate with my i5 3rd gen Dell E6320 laptop is ~100 Hz! despite Intel onboard HD 3000 graphics.

Here is another shot with 2 Irr galaxies on ONE screen. Look again at the 4 red arrows.
Here I used the same template though (just for testing).

[click on image and use browser fullscreen by all means!]


3) The code for reading in the generated data and rendering the new DLA structures is fully embedded in the .Sci code (galaxy.cpp).

Note that I did NOT spend any time yet for tuning the sprite rendering and other rendering aspects like color! You see again plenty of pink HII regions (possibly too many...)

Fridger

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I decided to move my progress reports about DLA-based rendering of Irregular Galaxies here, since these constitute an important development aspect of celestia.Sci.

Fridger

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