It is currently Tue, 25-07-17, 16:44 GMT

All times are UTC




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Mon, 10-02-14, 16:55 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
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:
+++++
Attachment:
lmc_dla.jpg
lmc_dla.jpg [ 86.23 KiB | Viewed 2487 times ]


DDO 64
+++++++
Attachment:
ddo64.jpg
ddo64.jpg [ 74.1 KiB | Viewed 2487 times ]


Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Mon, 10-02-14, 18:09 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
Here is a "kingsize" image of NGC 4449 with pink HII regions activated

[click on image + browser fullscreen by all means!]
Attachment:
n4449_dla.jpg
n4449_dla.jpg [ 168.32 KiB | Viewed 2486 times ]


Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Tue, 11-02-14, 21:51 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
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!]
Attachment:
n4449_dla2.jpg
n4449_dla2.jpg [ 137.67 KiB | Viewed 2461 times ]


Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Wed, 12-02-14, 18:57 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
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!]
Attachment:
ddo127.jpg
ddo127.jpg [ 105.48 KiB | Viewed 2442 times ]


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!]
Attachment:
ddo64.jpg
ddo64.jpg [ 142.38 KiB | Viewed 2442 times ]


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

_________________
Image


Top
 Profile  
 
PostPosted: Wed, 12-02-14, 21:10 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
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

_________________
Image


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group