Celestia Forums

Together with Buggs Moran I'm realizing the Ptolemaic Solar System addon (and more to come), but we are not yet satisfied, due to the problem of planet name and orbit (more exactly the epicycle, i.e. the orbit of the planet around an invisible point rotating around the Earth), disappearing as distance increases.
I would like to have a more clear idea of what is (or are) the parameter/s that define the limit of visibility of planet names and their orbits, and eventually what can I do to obtain they to show or not to show, but all together.
BTW all the objects in this addon have been defined as class "planets".

Distance 15- Here we see all epicycles and names


Distance 16- No more Moon (Luna) epicycle (no image)

Distance 19- No more Moon (Luna) and Mercury (Mercurio) names


Distance 20- No more Mercury (Mercurio) epicycle(no image)

Distance 26- No more Mars (Marte) epicycle


Distance 27- No more Mars (Marte) name.


If the rule is the radius, Mars name/epicycle had to disappear before the Venus ones, and this is what happens.
So I equalized the objects dimensions, e.g. Moon, Mercury, Venus, Mars and Saturn all with (arbitrary) 18,000 radii, and Jupiter a bit bigger, 22,000 radius.
Well, things don't change, i.e. Moon, then Mercury, Mars, Venus, Jupiter and Saturn names/epicycles disappear in this sequence.
So, even if Saturn is smaller than Jupiter, it disappears last.
What the hell are the rules?
Please, can someone clarify this?
If you give a look at the last image, you can see that, at the distance where the StarSphere is perfectly visible, we have missed the names and the epicicles of the Moon (Luna), Mercury (Mercurio), Venus (Venere) and Mars (Marte), most of the planets, so that this is not so didactic as should be.
I have to add that many times, and this is the reason of the presence in the "Buggs" forum, mostrly when rotating the sysyem using the mouse right button, names disappear randomly.
Thank you

Andrea

Well, im quite new here, but y know, that whenever y selected a planet or star and than distanced away it was certainly drawed!

But if y selected sun, than in some cases moons or other planets that were further away were not drawed!

Y wrote a program in Msvisual basic 6.0 and a problem occured!

The objects(stars or planets) that were too far away were big as an dot--
"." or dissapeared! This way y had to program in "pixel art" .

In basic is like Peek or poke and some number......(i have to avoid "line(or point...e.t.c) (xxx,xxx,xxx)-(xxx,xxx,xxx)"

When closing to a star (that is drawn as a dot- far away), it does not grow linearly! It seems, that celestia has some "step" walues- (closing to stars or magnitude)
When changing magnitude, the brightness of stars has some "steps". An that is not real.

Maybe the answer is in this direction.
But certainly WE NEED SOME PATCH!
(that would give celestia support for dx9.c and 3.0 shader and so on )

ANDREA,

as you know, it was me who originally coded the "dynamical label display" for galaxies. Latest during the weekend, I might find the time to discuss precisely the various conditions in the code. In any case, as far as I know, my dynamical galaxy labels work quite satisfactorily.

Later Chris adapted my code almost 1-to-1 to star and planetary labels. So I would have to look in detail there to possibly spot some oddities that seem to disturb you.

As I mentioned to you privately, the best would probably be to allow for an ON|OFF flag for dynamical label display in celestia.cfg

Cheers,
Fridger

t00fri wrote:ANDREA, as you know, it was me who originally coded the "dynamical label display" for galaxies. Latest during the weekend, I might find the time to discuss precisely the various conditions in the code. In any case, as far as I know, my dynamical galaxy labels work quite satisfactorily. Later Chris adapted my code almost 1-to-1 to star and planetary labels. So I would have to look in detail there to possibly spot some oddities that seem to disturb you.
As I mentioned to you privately, the best would probably be to allow for an ON|OFF flag for dynamical label display in celestia.cfg
Cheers, Fridger

Sorry for my late reply, Fridger, but I was on holiday in Greece, so I've seen your post just now.
I know what you are doing, and as I told you I think your proposal satisfactory for this problem, with only one doubt: the ON-OFF label switch will be submitted to the distance of the objects to be labelled, or not?
I mean, if I switch ON the planets labels, and in my field there are some stars with known planets, their labels will be visible the same?
Obviously I don't need this, and this is the reasson of my question.
If the reply is yes, could not be better to put a distance switch, e.g. "Show planets-moons labels up to -xxxx- AU" (100- 1000 or so).
Anyhow, whatever will be your decision, I'll wait patiently the solution, when it will be ready.
Thank you

Andrea

ANDREA wrote:

t00fri wrote:ANDREA, ... As I mentioned to you privately, the best would probably be to allow for an ON|OFF flag for dynamical label display in celestia.cfg
Cheers, Fridger

...I think your proposal satisfactory for this problem, ....could be better to put a distance switch, e.g. "Show planets-moons labels up to -xxxx- AU" (100- 1000 or so).
Anyhow, whatever will be your decision, I'll wait patiently the solution, when it will be ready.
Thank you. Andrea

After one full year I'm again here on the same problem, so I?€™m sure no one will say that I?€™m hurrying up developers to find its solution.
I summarize the problem: the planets/moons labels disappear randomly as distances from observer increase.
I've been unable to understand if not only observer/object distance has influence on their disappearing, or object dimensions too have some influence, so I kindly ask for a solution that could solve this problem, i.e. the persistence of BOTH orbits AND labels up to a chosen distance limit, without influence from other parameters, i.e not this way



but THIS way!



Obviously I'm only asking this for star systems environment, i.e. planets, moons, asteroids, etc. not for galaxies or what else.
Fridger's solution of an ON-OFF flag in celestia.cfg file IMHO is the simplest and more efficient, but please with an addiction, the possibility to choose at will a limiting distance, e.g. 150 AU.
This will allow a ?€?fine tuning?€

Celestia stops rendering an object's orbit and label when the size of its orbit is below some threshold. That threshold is a size in pixels, because the idea is to avoid cluttering the screen with overlapping labels. There's a script command to set this threshold. The default value is 20 pixels, but this line of celx script will set it to be just a single pixel:



Now, there's been some discussion of enabling a magnitude based fading effect for planet, moon, and asteroid labels (similar to the one for stars and galaxies.) If that was added, you would probably want a new script command to turn it off for your add-ons.

--Chris

chris wrote:Now, there's been some discussion of enabling a magnitude based fading effect for planet, moon, and asteroid labels (similar to the one for stars and galaxies.) If that was added, you would probably want a new script command to turn it off for your add-ons.

I don't think that label fading is a good idea in the case of planets, since there isn't so many planets around in the same system. The planet labels fading effect currently enabled in 1.5.0pre3 is already perfect. However, the label fading you're talking about could be very usefull in the case of the moons (especially for Jupiter and Saturn), and, of course, asteroids and comets (which is actually a must have).

Cham wrote:

chris wrote:Now, there's been some discussion of enabling a magnitude based fading effect for planet, moon, and asteroid labels (similar to the one for stars and galaxies.) If that was added, you would probably want a new script command to turn it off for your add-ons.

I don't think that label fading is a good idea in the case of planets, since there isn't so many planets around in the same system. The planet labels fading effect currently enabled in 1.5.0pre3 is already perfect. However, the label fading you're talking about could be very usefull in the case of the moons (especially for Jupiter and Saturn), and, of course, asteroids and comets (which is actually a must have).

Chris and Cham, first of all thank you for your reply.
Sorry, I forgot to say that my images are from 1.4.1, so I don?€™t know if Chris?€™ information is applicable to this release.
Anyhow, my situation is a bit different from the one of ?€?normal?€

Andrea,

Setting the Minimum Orbit Size to be rendered is also possible in CEL scripting.
So you might solve your problem by simply adding the following line at the beginning
of your start.cel (or start_it.cel) file:

This should work with both the official 1.4.1 and the Celestia_1.4.1_patch3 versions.

Vincent wrote:Andrea, Setting the Minimum Orbit Size to be rendered is also possible in CEL scripting.
So you might solve your problem by simply adding the following line at the beginning
of your start.cel (or start_it.cel) file:

Code: Select all

set { name "MinOrbitSize" value 3 }

This should work with both the official 1.4.1 and the Celestia_1.4.1_patch3 versions.

God bless you, Vincent, it works, look here:



So it was so easy, but no one remembered it before now?
Well, I'm astonished.
Thanks a lot once again, Vincent.
Buggs, we are on the job once again.
I'll post you soon.
Bye

Andrea

Vincent wrote:Andrea,

Setting the Minimum Orbit Size to be rendered is also possible in CEL scripting.
So you might solve your problem by simply adding the following line at the beginning
of your start.cel (or start_it.cel) file:

Code: Select all

set { name "MinOrbitSize" value 3 }

This should work with both the official 1.4.1 and the Celestia_1.4.1_patch3 versions.

Won't work on 1.5?

Andrea,

what is the SSC (and STC ?) code for that system ? I may use it in my astronomy classroom.

And I don't think there's any "epicycle" for the Moon, in the Ptolemaic system. And Mars needs its "large" epicycle.

ANDREA wrote:Thanks a lot once again, Vincent.

You're welcome Andrea.

ElChristou wrote:Andrea,Won't work on 1.5?

Yes, this command also works on 1.5.
I don't know if this will be also the case of the whole addon, though.
Maybe Andrea can confirm...

Cham wrote:Andrea, what is the SSC (and STC ?) code for that system ? I may use it in my astronomy classroom.
And I don't think there's any "epicycle" for the Moon, in the Ptolemaic system. And Mars needs its "large" epicycle.

Cham, the image I showed here is from an old ssc/stc, prepared together with Chris (Buggs Moran) a lot of time ago.
I don't remember what is the exact situation of Ptolemy's epycicles, it's one year that I don't give a look at them, but one thing is sure, we checked a lot of documents, so the final release will be the closest possible to Ptolemy's idea of our Solar System.
Now that the problem of disappearing orbits is solved, together with Buggs Moran, that already gave his OK to go on, we'll start to check what has been already produced (we have the Tychonic system almost ready, too!), and go on with the Copernican, Keplerian, Galileian and Modern Solar System.
Once done all this, we'll produce a cel or celx script that will bring the students to visit the 6 different conceptions of the Solar System.
Give us some more time, and we'll bring to the community a pleasant and interesting (we hope) piece of History of Astronomy.
Bye soon.

Andrea

Vincent wrote:

ElChristou wrote:Andrea,Won't work on 1.5?

Yes, this command also works on 1.5.
I don't know if this will be also the case of the whole addon, though.
Maybe Andrea can confirm...

Yes, just checked, the full addon works in 1.5.0pre3 (last official release).
I'm very happy of this, because the future (not so far away, anyhow) "The Ancient Solar Systems" addon will be usable with the new 1.5 release too.
Bye soon

Andrea

ANDREA wrote:

Vincent wrote:

ElChristou wrote:Andrea,Won't work on 1.5?

Yes, this command also works on 1.5.
I don't know if this will be also the case of the whole addon, though.
Maybe Andrea can confirm...

Yes, just checked, the full addon works in 1.5.0pre3 (last official release).
I'm very happy of this, because the future (not so far away, anyhow) "The Ancient Solar Systems" addon will be usable with the new 1.5 release too.
Bye soon

Andrea

Cool! Can't wait to see this work!!

I've ever hoped to see that in Celestia! Now the program is complete! Incredible thanks, Andrea and Buggs! The old universe come back! Only a question (if not out of thread): for what concern the diurnal rotation of the zodiac?

Fenerit wrote:I've ever hoped to see that in Celestia! Now the program is complete! Incredible thanks, Andrea and Buggs! The old universe come back! Only a question (if not out of thread): for what concern the diurnal rotation of the zodiac?

Hello Fenerit, happy that you like it, even if it's not ready to spread.
Well, we started working again, so we hope to issue the package, or at least the Ptolemaic system, in a short time.
Regarding your question, can you please explain me what do you mean?
i'm ignorant of this, but surely Buggs will follow you.
Bye soon.

Andrea

Never mind if the old systems there are not in Celestia yet, the important is that they WILL be.

For the diurnal rotation I mean the movement of the fixed stars that carried the Sun and the other planets around the Earth in 24h.

Fenerit wrote:Never mind if the old systems there are not in Celestia yet, the important is that they WILL be.
For the diurnal rotation I mean the movement of the fixed stars that carried the Sun and the other planets around the Earth in 24h.

Understand.
We'll give a look.
Bye

Andrea