New spiral galaxy types rendering

[guest jo]

deleted

[Verteiron]

Hello to our wonderful code developpers.
I'm looking forward to these big improvements of celestia's galaxies.

Just a thought:
1. Would it be possible to render the Milky Way in a way that it also looks better from the inside ? Or is this included in the actual development-process?

2. Will it be possible for the user to get (adjust?) a realistic visibility of galaxies:
( Miky way visible; Andromeda very hardly visible; others invisible ) ?

Well, here are a couple of screenshots of the Milky Way from a position near Earth with Toti's new galaxy code (and dirkpitt's patch):
http://cosmicjive.org/verteiron/celestia/nmway1.png
http://cosmicjive.org/verteiron/celestia/nmway2.png

And here are a couple of shots at about 20% light amplification so you can see the structure better:
http://cosmicjive.org/verteiron/celestia/nmway3.png
http://cosmicjive.org/verteiron/celestia/nmway4.png

As for your second question, I think I remember a thread on this from a long time ago. The consensus reached there was that since the contrast ratio of a monitor cannot even approach the contrast ratio of the universe, "realistic" visibility of stellar bodies can't be acheived. This is why (in Celestia) you can see the sun-lit Earth in front of the Milky Way; in real life the Earth would wash the Milky Way out completely and render it pretty much invisible to human eyes. Check back when the hardware catches up to real life

[t00fri]

Hi all,

I want to let interested people know that I have now produced a new galaxy.dsc file with 6520 galaxies from Steinicke's precision revised NGC catalog. There is another part virtually ready, the revised IC catalog, containing another 4000+ galaxies.

What is still missing, are the correct angle-axis orientation entries.

Chris has promised days ago to help sorting out some respective subtleties with Celestia's coordinate frames that I need to know to do the required transformations of galaxy position angle and inclination from the catalog data. I hope he manages to reply during this weekend. Then I could finish the job right away and publish my preliminary results for testing.

If not,... I have a very busy week ahead of me and then won't find any further coding time until next weekend at the earliest...

There are some most impressive "galaxy cluster images" now displayed in Celestia (with the galaxy patch). Perhaps tomorrow, I'll display some nice examples (once our weekend visitors are gone )

For example the region around the famous Stephan's Quintet, so far only from a DSS2 photograph.


Tomorrow you'll see how Celestia is doing around here

Bye Fridger

PS:

The new galaxy.dsc catalog, so far looks like this:

Code: Select all


# Revised NGC and IC Catalog, Wolfgang Steinicke, April 5, 2005
# http://www.ngcic.org/steinicke/default.htm
# adapted for Celestia with Perl extraction script: ngc2dsc.pl Revision: 1.00
# Processed 2005-5-28 20:15:20 UTC
# by Dr. Fridger Schrempp, fridger.schrempp@desy.de
# ------------------------------------------------------

#  NGC 1
Galaxy "NGC 1"
{
        Type  "Sb"
        RA           0.1208
        Dec          27.7089
        Distance     2.101e+08
        Radius       5.195e+04
}

#  NGC 2
Galaxy "NGC 2"
{
        Type  "Sab"
        RA           0.1214
        Dec          27.6786
        Distance     4.003e+08
        Radius       5.823e+04
}

#  NGC 3
Galaxy "NGC 3"
{
        Type  "S0"
        RA           0.1211
        Dec           8.3014
        Distance      2.77e+08
        Radius       4.431e+04
}

#  NGC 4
Galaxy "NGC 4"
{
        Type  "S0"
        RA           0.1233
        Dec           8.3739
        Distance     8.758e+08
        Radius       7.643e+04
}


...+ 6516 further entries

[guest jo]

deleted

[Cham]

Fridger,

can you give a detailed example of a galaxy with color variables and the various types that could be used, alongside the standard elliptical and S ?

[t00fri]

Fridger,

can you give a detailed example of a galaxy with color variables and the various types that could be used, alongside the standard elliptical and S ?

I could, but it takes time... Since Chris does not care to answer (despite his promise), I am working the transformations out myself. Since I made some important progress with the signs involved, I want to stay at it as long as I still have some time left...

I tediously dug out those bluddy (unusual) sign conventions from the code... One further rotation and I am done (I hope)

Bye Fridger

[Cham]

Well, I mean in the dsc code, how do you define the galaxy color ? Is there a well defined command for this ?

[t00fri]

Well, I mean in the dsc code, how do you define the galaxy color ? Is there a well defined command for this ?

No, not yet! So far the color assignments have to be hardwired in galaxy.cpp. I did propose respective changes to Chris, but ...no answer. Probably Chris is off mountain climbing over the weekend?


Bye Fridger

[Cham]

Well, ok. I hope a color command could be implemented.

[t00fri]

Well, ok. I hope a color command could be implemented.

It's trivial to code, but we have to reach a consensus about what we want /first/. If Chris does not respond, we obviously have to wait.

Bye Fridger

[Cham]

Yes, but as the recent modifications were made independently from Chris, we could go along and make the color implementation without Chris, no ?

[t00fri]

Yes, but as the recent modifications were made independently from Chris, we could go along and make the color implementation without Chris, no ?

I'll get at that as soon as those bloody orientation tansformations are implemented. Actually, I am almost DONE!

Bye Fridger

[PlutonianEmpire]

Hello to our wonderful code developpers.
I'm looking forward to these big improvements of celestia's galaxies.

Just a thought:
1. Would it be possible to render the Milky Way in a way that it also looks better from the inside ? Or is this included in the actual development-process?

2. Will it be possible for the user to get (adjust?) a realistic visibility of galaxies:
( Miky way visible; Andromeda very hardly visible; others invisible ) ?

Well, here are a couple of screenshots of the Milky Way from a position near Earth with Toti's new galaxy code (and dirkpitt's patch):
http://cosmicjive.org/verteiron/celestia/nmway1.png
http://cosmicjive.org/verteiron/celestia/nmway2.png

And here are a couple of shots at about 20% light amplification so you can see the structure better:
http://cosmicjive.org/verteiron/celestia/nmway3.png
http://cosmicjive.org/verteiron/celestia/nmway4.png

As for your second question, I think I remember a thread on this from a long time ago. The consensus reached there was that since the contrast ratio of a monitor cannot even approach the contrast ratio of the universe, "realistic" visibility of stellar bodies can't be acheived. This is why (in Celestia) you can see the sun-lit Earth in front of the Milky Way; in real life the Earth would wash the Milky Way out completely and render it pretty much invisible to human eyes. Check back when the hardware catches up to real life

Umm, shouldn't the milky way be a bit more bluish or something?

[hank]

Probably Chris is off mountain climbing over the weekend?

This is a three-day holiday weekend in the USA ("Memorial Day", in remembrance of the nation's war dead, is observed on Monday), and the weather in Seattle has been sunny and warm lately, so it's a good guess that Chris is off somewhere doing something fun. At least let's hope so!

-Hank

[ElChristou]

Well, the three day is over and I was wondering:

What are the advance with this work? All begun very fast, but since a while now, nothing else...
Is there some problem?

[t00fri]

Well, the three day is over and I was wondering:

What are the advance with this work? All begun very fast, but since a while now, nothing else...
Is there some problem?

This stuff was very work intensive, since I had to tediously sort out all those /non-canonical/ frame conventions in Celestia from the code, since there is no precise written documentation and Chris did not react...He was indeed in the mountains as Hank and I speculated.

But now I have derived the formulae, it's all done and looks nice. See my new thread <=> users -> "10000+ Galaxies, Status Report".

Bye Fridger

[t00fri]

Some further ideas on implementing galaxy color:

We all know that the human eye cannot see color once the light level is below a certain threshold value! That's the reason why amateur astronomers see galaxies in their telescopes as GRAY images rather than colored. Only photographic imaging that is able to sum up the incoming light quanta shows those beautiful colors!

My idea is to implement galaxy colors (as derived from the catalog data) only when the distance to the galaxy becomes small enough or the zoom level sufficiently high! In the limit of "weak intensity", color will fade out, in agreement with visual (far distance) observations. This might give dramatic effects, when we approach a galaxy in Celestia....

Bye Fridger

[maxim]

Yes, agreeing. But I'd like to have a 'forced colors' switch, so that we can generate a 'celestia deep field' similar to the colorfull 'huble deep field' pictures.

maxim

[guest jo]

deleted

[steffens]

Instead of polishing around switches or sliders, I think it would be more useful to have the new galaxy rendering code in CVS, even if it is not 100% finished and perfect.
But I guess this depends upon Chris to approve the change...

steffens