Cepheid Variables

[selden]

Fridger,

It seems (or rather, I know for a fact) that Celestia is being used in a lot of places as a teaching tool, by people who never post to this forum, or who may not even know it exists. I just wish some of them would comment on these ideas

[don]

I find this topic and idea fascinating. Also agree that the beginning "instruments" should be kept simple to learn / understand, and simple to use. They can be built into "professional" models with advanced features as time permits.

Why? ...

There are a LOT of folks who simply do not have the un-disturbed "free time" that many of us here enjoy. They have demanding spouses, kids, dogs, cats, friendly neighbors, etc., not to mention long work / school hours. Thus, their available "free time" to learn new things is limited to short, heavily-interrupted "chunks".

Also, many of Celestia's users probably know little or nothing about astronomy, celestial mechanics, astrophysics, etc. (like myself), but they want to learn more! Which means Celestia may become their tool-of-choice to enhance their personal knowledge -- if it is kept easy enough to learn and use.

This is why I believe that new things in Celestia (that relate to running it) should be kept as easy / quick to learn and understand as possible ... except for things like scripting, model making, creating textures, etc. all of which are above and beyond merely running Celestia -- whether for pure enjoyment or education.

Just my 2 cents worth.

-Don G.

PS. It's late and I'm tired, so please forgive me if I have not expressed my feelings using all the right words.

[Toti]

E.g. if you go from mercury to pluto in this mode, you wouldn't see much of pluto because it's too dark... (assuming the brightness range is set for mercury).

This seems very strange to me. I'm moderately accepting of the notion of expanding the user's sensitivities to light and other portions of the EM spectrum. But you seem to be offering the user the option to limit his/her range of sensitivity in order to produce an effect that wouldn't appear in real life. It's like offering the option of red/green colour-blindness - I just don't see a reason, or a way in which this would appeal to the user.

I think of Celestia as a powerful teaching tool. The effect of light dimming across distance from light source is one of this subtle notions that most people tend to overlook and even ignore.
Common science oriented entertainment as TV shows, movies, etc. usually presents visual material where -among other simplifications- light intensity is constant along distance. It is obvious that this is due to practical reasons, mostly the same reasons that induced Celestia developers to adopt such "no dimming light" approach.
But I still think that a space simulator needs a much more ambitious lighting model. One of the phenomena that this complex model must consider is the calculus of light intensity at a given point from its source.

It would be precisely equivalent to having a DVD movie that offered a "realistic lighting" option which blacked out all the indoor scenes!

I am well aware that this implementation will limit the viewer perception capability while it is being used. But, please, I don't think of it as a permanent limitation (which will absurdly impoverish the viewer's experience), but as a flag that can be switched on/off as today 'automag' mode can. This way, and specially under script control, real light dimming simulation will be a new variable that undoubtely will strenghten Celestia scientifical accuracy and teaching value.

Also, I think that the referred tiny variability of Cepheids is of educational merit. From some time ago, Cepheids had increasing presence in science divulging media. So this name became quite sounding. I can imagine all kind of exaggerated Cepheids renderings, showing espectacular size and brightness cycling being shown in TV science-popularising programs. There might even exist some confusion in the sense of grouping all variable stars under the name of Cepheids Variables (this might even be the case with the origin of this thread) So being able to show how small their scale/bright change really is must be of great teaching importance.

The illumination at Pluto's distance from the Sun is, in fact, about the equivalent of indoor electric lighting. Most people are astonished to discover that indoor lighting is so much dimmer than sunlight, because their eyes compensate so well for the altered level of illumination. So my concern about "dark Pluto" options is that the are extremely unrealistic.

Let me explain that I tought of Pluto as an example of a far world, without implying accuracy at all. But even in the case that you are pointing to, it takes some time to the human visual system to adapt to the scene lighting change. This is specially true when the mentioned change is a fast one. Celestia allows to travel from Mercury to Pluto in a few seconds. Because the showed brightness of both planets is much the same, the unaware viewer will naturally be unallowed to think that the lighting conditions on Mercury and Pluto are indeed very different.
Now imagine the same situation but with realistic light rendering enabled: the user is taken to Pluto, and he sees almost nothing, until his eyes start to compensate. This makes me believe that a switchable, speed-adjustable simulation of brightness perception adaptation over time can be a valuable feature to be incorporated into Celestia.

And an issue was mentioned concerning the ilumination of extrasolar planets orbiting very tenuous stars. It was stated that the lighting of such bodies is somewhat exaggerated by Celestia in order to let the user perceive them. With the above described features enabled, a more accurate rendering of these environments is possible.

[Bob Hegwood]

It seems (or rather, I know for a fact) that Celestia is being used in a lot of places as a teaching tool, by people who never post to this forum, or who may not even know it exists. I just wish some of them would comment on these ideas

If I *may* Mr. Ball...

I've noticed that a LOT of users come and go without saying much. This - in my opinion - is because quite a few of them get jumped on for trying to offer ideas and suggestions. Sorry, but that's certainly the way I see it happening.

You have been *very* helpful with your advice and assistance when somebody asks a dumb question, but I have personally been attacked here for either expressing an opinion which went against the grain, or for just being my lovable self.

The way people get treated here may have quite a bit to do with why there aren't more people getting involved with the project.

Now before you all start jumping on me again. Think about what I'm saying here. I have had quite a few personal messages agreeing with this premise.

I realize that I'm no scientist, but clearly I *do* have something to offer. Even if it's only a script or two, that's a script or two that wouldn't have existed otherwise. You might try encouraging feedback instead of telling people why they're so stupid for asking a dumb question.

I know for a fact that many Celestia users simply hang out here as guests, and then take any interesting bit of code, or an image map from these conversations and never say a single word.

Admittedly, I'm a bit more bull-headed than most, but this is a trend that should be avoided at all costs in my opinion.

Love ya's, Bob

[t00fri]

...
The way people get treated here may have quite a bit to do with why there aren't more people getting involved with the project.

Bob,

being a member of this Forum almost since its beginning 2 years ago, I would have another observation to add:

Many "knowledgable" people have shut up more recently...

And I am also not referring to scientists in particular.

Bye Fridger

[Bob Hegwood]

Dr. Schrempp,

I'm sorry to hear that Sir...

In my opinion, it should be the other way around. Off-the-wall ideas and hare-brained schemes should be encouraged in this forum.

After all, we're talking about the universe here. I don't know about the rest of you, but I sure as hell don't know what lies out there, just around the next galaxy.

Take care, Bob

[don]

I also think that once a sufficiently general instrument class has been set up in the code, adding further ones will be increasingly less effort. A crucial aspect will concern the GUI's for such "instruments". They must be flexible, yet of universal structure and most of all: easy to operate at the user level.

A program I used a lot in the 90's (Cakewalk Pro Audio) did this very well! Cakewalk is a program for creating and mixing multiple MIDI and Audio file "takes" to create a single output audio file.

What they did was to create a "layer", that exists between the user and the program, whereby the user could create always-on-top "windows" (which they called "Panels") to contain any number of different pre-defined-shape "gadgets", such as dials, sliders, switches, level meters, etc., and attach the gadgets to playback and effects controls inside the program. The user could resize the controls, enter start and stop values, ranges, etc.

These Panels and their gadgets could then be used real-time, DURING playback, and all of their settings would be recorded. Just like an audio engineer would do on a real control panel. Several basic Panels were also provided with the program as examples.

Could something like this be done in OpenGL for Celestia's "instruments"?

-Don G.

[don]

I also think that once a sufficiently general instrument class has been set up in the code, adding further ones will be increasingly less effort. A crucial aspect will concern the GUI's for such "instruments". They must be flexible, yet of universal structure and most of all: easy to operate at the user level.

A program I used a lot in the 90's (Cakewalk Pro Audio) did this very well! Cakewalk is a program for creating and mixing multiple MIDI and Audio file "takes" to create a single output audio file.

What they did was to create a "layer", that exists between the user and the program, whereby the user could create always-on-top "windows" (which they called "Panels") to contain any number of different pre-defined-shape "gadgets", such as dials, sliders, switches, level meters, etc., and attach the gadgets to playback and effects controls inside the program. The user could resize the controls, enter start and stop values, ranges, etc.

These Panels and their gadgets could then be used real-time, DURING playback, and all of their settings would be recorded. Just like an audio engineer would do on a real control panel. Several basic Panels were also provided with the program as examples.

Could something like this be done in OpenGL for Celestia's "instruments"?

-Don G.