Stars far from home

[cartrite]

I've just mirrored my website at another host. My old website has been down for the last couple of days and has become undependable. The index page contains a link to an executable from SVN R4201. It was compiled with MS2008 C++ Express with the celestia.vcproj file. The original celestia.exe from 1.5.0 or 1.5.1 can be renamed for backup purposes and this file can replace the original which should give you the latest capabilities that are being discussed in this forum.

By just replacing the celestia.exe file from celestia 1.5.0 with the one from celestia-svn-r4201.zip. I took this screenshot after I used the 2 code segments chris posted on page 1 of this thread.




cartrite

[BobHegwood]

Thanks a lot for this my friend. The package I downloaded works
just fine, and your instructions were enviably easy to understand.

Again, many thanks, Brain-Dead Bob

EDIT: Oops... After further investigation, when I press the number
5 to get to Jupiter, I go to the asteroid Hektor instead. Same thing
for Saturn. I have to press 8 to get to Saturn and 7 causes Braille
to be selected. Any thoughts?

Thanks again though. I'll play with it some more.

[chris]

Thanks a lot for this my friend. The package I downloaded works
just fine, and your instructions were enviably easy to understand.

Again, many thanks, Brain-Dead Bob

EDIT: Oops... After further investigation, when I press the number
5 to get to Jupiter, I go to the asteroid Hektor instead. Same thing
for Saturn. I have to press 8 to get to Saturn and 7 causes Braille
to be selected. Any thoughts?

I'm pretty sure that this is caused by a bug in the Replace disposition for ssc files. I'll have a fix for it soon.

--Chris

[cartrite]

EDIT: Oops... After further investigation, when I press the number
5 to get to Jupiter, I go to the asteroid Hektor instead. Same thing
for Saturn. I have to press 8 to get to Saturn and 7 causes Braille
to be selected. Any thoughts?

Thanks again though. I'll play with it some more.

I'm not sure what you did to do this. I can't reproduce it. When I select a number, it goes where it is supposed to. The svn version is bound to have bugs though. Thats the nature of the beast.
cartrite

[Chuft-Captain]

Thanks for the build Cartrite.

I'm now able to test the new clickable property, and I'm sure there's a few other new features included that might be worth checking out.

[BobHegwood]

I'm not sure what you did to do this. I can't reproduce it. When I select a number, it goes where it is supposed to. The svn version is bound to have bugs though. Thats the nature of the beast.
cartrite

No problem... I simply renamed my old (1.5.0 Final) celestia.exe to
150celestia.exe, and then I replaced it with your celestia.exe file.
Chris mentioned the possible source of the problem in his post above
though, and I really appreciate your effort here, so no complaints
from me whatsoever.

Thanks, Brain-Dead Bob

[CAP-Team]

There's definitely a bug in the SVN version with the numbers.

In my installation the numbers are as follows:

1=Mercury
2=Ikeya-Zhang
3=Venus
4=Eros-post-near
5=Earth
6=Eros
7=Mars
8=Jupiter
9=Eros-pre-near

[chris]

There's definitely a bug in the SVN version with the numbers.

In my installation the numbers are as follows:

1=Mercury
2=Ikeya-Zhang
3=Venus
4=Eros-post-near
5=Earth
6=Eros
7=Mars
8=Jupiter
9=Eros-pre-near

I have a fix for this bug that I will be checking into CVS very shortly.

--Chris

[rra]

Will an executable do? I can keep an ongoing updated executable that can replace the original from 1.5.0. If and when my website is accessible that is. It seems to be going down a lot again.
cartrite

That would be a GREAT idea for those of us too lazy (or dumb) to
compile the things. Would be much appreciated here my friend.

Thanks, Bob

Remember also that there have been Windows-(SVN) builds on a regular basis by Phoenix:

http://www.purebytes.de/stuff/celestia/

Ren?©

[BobHegwood]

Remember also that there have been Windows-(SVN) builds on a regular basis by Phoenix:

http://www.purebytes.de/stuff/celestia/

Ren?©

I don't know why, but I really was not aware of this resource, so
thanks very much for the information. All appreciated.

[Derek]

Hi,

re: the planet number probleem, it seems to be a possible Vista problem?
I downloaded the build from Cartrite's web page using his directions
selecting the planets by number works no problem.

[BobHegwood]

Hi,

re: the planet number probleem, it seems to be a possible Vista problem?
I downloaded the build from Cartrite's web page using his directions
selecting the planets by number works no problem.

Anything is possible. I just updated Vista with 69 MB of Service Pack
1, so I'll see if that made any difference.

Thanks, Bob

[ajtribick]

Back to the breaking the 16kly limit for a moment...

IIRC there's some special code to handle fading the brightness of the Milky Way when the observer is located inside the galaxy. Does this apply to other galaxies as well? If we're going to start putting stars in such galaxies, this should also be included for consistency.

[t00fri]

Back to the breaking the 16kly limit for a moment...

IIRC there's some special code to handle fading the brightness of the Milky Way when the observer is located inside the galaxy. Does this apply to other galaxies as well? If we're going to start putting stars in such galaxies, this should also be included for consistency.

Certainly, I coded this correction for any galaxy. The effect only depends on the variable distanceToDSO.

Code: Select all

double ri  = -0.1, pc10 = 32.6167;
double r   = absMag / avgAbsMag;
double num = 5 * (absMag - faintestMag);
double a   = r * (avgAbsMag - 5 * faintestMag) / num;
double b   = (1.0 - 5 * r) / num;
double close = (distanceToDSO > -10.0)?
               -4.3429448 * b * log((pc10 +distanceToDSO)/(2 * pc10)): ri;
            // note: 10.0 / log(10.0) = 4.3429448
            if (distanceToDSO < 0)
               distanceToDSO = 0;
double brightness = (distanceToDSO  >= pc10)? a - b * appMag: r + close;


Note that distanceToDSO here refers to the DSO boundary, NOT it's center (i.e. distanceToDSO becomes negative within the galaxy radius=dsoRadius).

However this is still quite a rough approximation, not accounting for the specific galaxy shape. It's essentially tuned for the location of Earth within the Milky Way. For other galaxies we don't have any corresponding observational data.


F.

[Reiko]

I noticed when I put a star similar to that of Sol about 100,000ly out the star balloons up into an ultra bright ultra large giant.

[chris]

I noticed when I put a star similar to that of Sol about 100,000ly out the star balloons up into an ultra bright ultra large giant.

Could you post your stc definition? My guess is that you changed the distance of a nearby star without changing it's apparent magnitude. Let's say you have two stars that have the same apparent brightness as seen from Earth, with one star 10 light years away and the other 500 light years away. The second star has to be intrinsically 2500 times as bright as the first: (500/10)^2=2500. Unless you changed the temperature (by modifying the spectral type), this increase in brightness will be due to an increase in the size of the star.

--Chris

[selden]

Reiko,

I betcha you specified AppMag with the same value as you would specify for the Sun. That's the apparent magnitude -- how bright it looks to us no matter how far away it is.

A star 100000 LY away which is bright enough to cast shadows the way the Sun does would indeed have to be incredibly large and luminous!

If instead you specified the same AbsMag, it'd be a dwarf star like our Sun. The Absolute magnitude specifies how bright a star would be when it is observed from a distance of 10 parsecs (32.6 light years).

[Reiko]

I noticed when I put a star similar to that of Sol about 100,000ly out the star balloons up into an ultra bright ultra large giant.

Could you post your stc definition? My guess is that you changed the distance of a nearby star without changing it's apparent magnitude. Let's say you have two stars that have the same apparent brightness as seen from Earth, with one star 10 light years away and the other 500 light years away. The second star has to be intrinsically 2500 times as bright as the first: (500/10)^2=2500. Unless you changed the temperature (by modifying the spectral type), this increase in brightness will be due to an increase in the size of the star.

--Chris

Reiko,

I betcha you specified AppMag with the same value as you would specify for the Sun. That's the apparent magnitude -- how bright it looks to us no matter how far away it is.

A star 100000 LY away which is bright enough to cast shadows the way the Sun does would indeed have to be incredibly large and luminous!

If instead you specified the same AbsMag, it'd be a dwarf star like our Sun. The Absolute magnitude specifies how bright a star would be when it is observed from a distance of 10 parsecs (32.6 light years).

Thanks guys the appMag is the problem. I was leaving it the same.
The STC file I was testing does not have AbsMag listed, just the App.

Code: Select all

033566822 "tyc"
{
RA  135.54182622
Dec 8.59013742
Distance  101420.75
SpectralType "G7 V"
AppMag 7.37
}


Could I just remove that AppMag and replace it with AbsMag and have the value the same as sol?

[selden]

Reiko,

Yes, you can replace AppMag by AbsMag so the star's size will not change at different distances. If you look in Celestia's nearstars.stc, the very first star defined there is the Sun, including its AbsMag value: 4.83

[Spaceman]

I like this version and I'm very happy putting stars in great distances . But i notice 2 strange things

1) I download and install 2 normal maps for the Moon and Mars. I visit this worlds but i can't find any change with the normal maps.

moon.jpg

2) At some star systems, about 1 light year before i get closer, i watch this!

starsystem.jpg

What's this?

This both things are bugs?