Can someone tell me what I'm doing wrong here?

[BobHegwood]

Hi again...

I am having extreme difficulty in trying to figure out how to install and use Jack Higgins' pathfinder and sojourner models for Mars. The components are available on Jack's page HERE.

Could someone please tell me what I have to do in order to repair these add-ons for use in Celestia 1.5.1? I have tried, believe me, but I simply do not have the knowledge necessary in order to get these to work correctly. No matter what I do, the add-ons end up inside Mars. Any help here? The existing ssc code is listed below.

Code: Select all

" " "Sol/Mars"
{
Radius 1
Mesh "empty.3ds"
EllipticalOrbit {
Period 9e200
SemiMajorAxis 1123.446228
AscendingNode 136.005
Inclination 90
MeanAnomaly 90
}

}

"Mars Pathfinder" "Sol/Mars/ "
{
Class "spacecraft"
Mesh "pathfinder.3ds"
Radius 0.00546

EllipticalOrbit {
Period 1.02595675
SemiMajorAxis 3202.682272
MeanLongitude 282.485
}

Orientation [20.18809 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

"Sojourner Rover" "Sol/Mars/ "
{
Class "spacecraft"
Mesh "sojourner.3ds"
Radius 0.00070463

EllipticalOrbit {
Period 1.02595675
SemiMajorAxis 3202.681072
MeanLongitude 282.4852
}

Orientation [20.18809 1 0 0]
RotationOffset 192.485

Albedo 0.50
}


Thanks, Brain-Dead Bob

[selden]

Using an extra orbit was a hack devised by Grant Hutchison to persuade an object to stay at a specific position relative to a planet's surface.

The LongLat statement instead would be more appropriate for recent versions of Celestia.

[BobHegwood]

Using an extra orbit was a hack devised by Grant Hutchison to persuade an object to stay at a specific position relative to a planet's surface.

The LongLat statement instead would be more appropriate for recent versions of Celestia.

Yes, I also tried that, Selden, but I'm afraid that something else must be in error.
In the ssc code in my first post here, I removed all of the blank hacks, and I tried playing with the semimajoraxis values in order to locate the objects on the surface of Mars. Still no luck however.

Will experiment some more and see if I can figure it out. I just thought that someone might already have these objects displayed properly on Mars' surface.

Thanks a lot, Bob

[ANDREA]

Bob, just to give you a possible solution, in Celestia 1.4.1 this works flawlessly:

" " "Mu Cas/Mars"
{
Class "invisible"

EllipticalOrbit {
Period 9e200
SemiMajorAxis 1110.295
AscendingNode 136.005
Inclination 90
MeanAnomaly 90
}
}

"Mars Pathfinder" "Mu Cas/Mars/ "
{
Class "spacecraft"
Mesh "pathfinder.3ds"
Radius 0.00546

EllipticalOrbit {
Period 1.02595676
SemiMajorAxis 3215.377
MeanLongitude 102.4811
}

Orientation [19.0949 1 0 0]
RotationOffset 12.4812

Albedo 0.50
}

"Sojourner Rover" "Mu Cas/Mars/ "
{
Class "spacecraft"
Mesh "sojourner.3ds"
Radius 0.00070463

EllipticalOrbit {
Period 1.02595676
SemiMajorAxis 3215.3758
MeanLongitude 102.4810
}


Orientation [19.0949 1 0 0]
RotationOffset 12.4809

Albedo 0.50
}

I have this Mars aroung Mu Cas, so obviously you have to change it.
Hope this helps.
I never tried in 1.5.1 because for my "Mars, the Red Planet" show I need Vincent's celestia_1.4.1_patch3.exe that allows the use of music and sounds within cel script.
Sorry.
Bye

Andrea

[SU(3)xSU(2)xU(1)]

This works perfectly in Celestia 1.5.1 and doesn`t have any hacks.

Code: Select all

"Mars Pathfinder" "Sol/Mars"
{
Class "spacecraft"
Mesh "pathfinder.3ds"
Beginning "1997 07 04"
Radius 0.00546
LongLat [-33.52 19.31822 0.00139]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

"Sojourner Rover" "Sol/Mars"
{
Class "spacecraft"
Mesh "sojourner.3ds"
Beginning "1997 07 04"
Radius 0.00070463
LongLat [-33.5198 19.31822 0.00064]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

Paul

[ANDREA]

Bob, I tried it with Celestia 1.5.0, and it equally works flawlessly, provided that I slightly changed the semimayor axes, as follows:

"Mars Pathfinder" "Sol/Mars/ "
SemiMajorAxis 3396.003

"Sojourner Rover" "Sol/Mars/ "
SemiMajorAxis 3396.0028

with Mars having

"Mars" "Sol"
Radius 3396 # equatorial

Look at the image.

Bye

Andrea

[SU(3)xSU(2)xU(1)]

Andrea,

I don't understand, why do you prefer such an ancient method. Bob was clearly asking about Celestia 1.5.1.

Paul

[ANDREA]

Andrea, I don't understand, why do you prefer such an ancient method. Bob was clearly asking about Celestia 1.5.1.
Paul

Paul, I explained clearly (or at least I supposed to have done it) the reason why I use that old (but working) way to show Soyurner and Rover with 1.4.1 and consequently its ssc way.
I know that there are new ways to do it, but I prefer to avoid the negative results obtained by Bob, because IMHO there is an enormous lack of detailed and organized information about ALL the new available stuff.
It looks like the new and very important improvements are more oriented to the "elite" that partecipate to the development, than to the poor people like I am.
This is only my opinion, obviously.
So if Bob will use my suggestion, even with 1.5.0, it will work flawlessly, otherwise he will need to study the new ssc commands, but I don't know where to do it, alas.
Bye

Andrea

[SU(3)xSU(2)xU(1)]

Andrea,

So if Bob will use my suggestion, even with 1.5.0, it will work flawlessly, otherwise he will need to study the new ssc commands, but I don't know where to do it, alas.

Actually Bob doesn't need to study anything. It' s enough for him to use the following code in his ssc file:

Code: Select all

"Mars Pathfinder" "Sol/Mars"
{
Class "spacecraft"
Mesh "pathfinder.3ds"
Beginning "1997 07 04"
Radius 0.00546
LongLat [-33.52 19.31822 0.00139]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

"Sojourner Rover" "Sol/Mars"
{
Class "spacecraft"
Mesh "sojourner.3ds"
Beginning "1997 07 04"
Radius 0.00070463
LongLat [-33.5198 19.31822 0.00064]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}


Paul

[chris]

Andrea, I don't understand, why do you prefer such an ancient method. Bob was clearly asking about Celestia 1.5.1.
Paul

Paul, I explained clearly (or at least I supposed to have done it) the reason why I use that old (but working) way to show Soyurner and Rover with 1.4.1 and consequently its ssc way.
I know that there are new ways to do it, but I prefer to avoid the negative results obtained by Bob, because IMHO there is an enormous lack of detailed and organized information about ALL the new available stuff.
It looks like the new and very important improvements are more oriented to the "elite" that partecipate to the development, than to the poor people like I am.
This is only my opinion, obviously.
So if Bob will use my suggestion, even with 1.5.0, it will work flawlessly, otherwise he will need to study the new ssc commands, but I don't know where to do it, alas.

Andrea,

I would appreciate some suggestions on how to improve the documentation. Vincent, Selden, myself, and others have been contributing to the Celestia WikiBook, which has a lot of information on creating SSC files:

http://en.wikibooks.org/wiki/Celestia/SSC_File

How could it be better organized? Would more tutorials be useful? More examples?

--Chris

[ANDREA]

Andrea, I would appreciate some suggestions on how to improve the documentation. Vincent, Selden, myself, and others have been contributing to the Celestia WikiBook, which has a lot of information on creating SSC files: http://en.wikibooks.org/wiki/Celestia/SSC_File. How could it be better organized? Would more tutorials be useful? More examples?--Chris

Chris, sorry if my post appeared as criticism to you and the other developers, this was not my intention.
In my opinion the problem (or MY problem, may be I'm the only one having it) is that, while I was used to and appreciated a lot e.g. Don Goyette's cel scripting guide, clearly written and filled with many examples, the other stuff made up to now is resulting, at least for me, in a plethora of information spread in a lot of posts, without any "compendium" of similar shape.
Yes, I know we have the Wiki ssc instructions page, and many more (Trajectories-Rotation Models-Using JPL Ephemerides with Celestia-Reference Frames), but it's missing a lot of examples, perhaps most of them, and this makes difficult and hard to understand a matter that, believe me, is not so well known by many Celestians, even if probably most of them will never admit it.
As you say, the Wiki pages on ssc (as all Wiki pages), are a collaborative gathering of information written and thought by different people, with different experience, feeling and behaviour with the subject.
For this reason I’m dreaming of a one-man instruction file, containing a lot of practical examples, that as you know are the best way to understand the matter in a shorter time.

BTW, just an example on Wiki problems:

Beginning f or "AAAA MM DD HH:MM:SS"
Specifies a time before which the object doesn't exist.
The Beginning time may be provided as a floating point number, in which case it is interpreted an astronomical Julian date, or it may be provided as a quoted string, in which case it is interpreted as a Gregorian date.
If it is a quoted Gregorian date, AAAA MM DD = year, month, day (integers); HH:MM:SS = hour, minute, second (integers). Since version 1.3.1, Celestia converts these time-stamps into Julian Dates internally. A date to Julian Date and back converter can be found at the U.S. Naval Observatory
http://aa.usno.navy.mil/data/docs/JulianDate.html

Sincerely, do you think that all Celestians know what “floating point number” is meaning?
Or what's the Astronomical Julian Date?
Wasn’t perhaps needed to explain that the JD is written this way: 2443711.139953?
More: why the beginning date is given as “AAAA MM DD” and no more as YYYY MM DD” as previously?
More: in the previous ssc definitions, written by Ulrich and Bob, it was given that "beginning" and "ending" could be written without the seconds, or with the AAAA MM DD only, so that it was possible to write as follows:
Beginning "1989 10 19 92:47:25" or
Beginning "1989 10 19 92:47" or
Beginning "1989 10 19"
Is this still OK?
If yes, it's missing in the wiki.
More. The web link to the U.S. Naval Observatory is OFF from many months, but this is the new one
http://www.aavso.org/observing/aids/jdcalendar.shtml

Please don't say me "why don’t you make it?", I would be very happy to be able to give my help on this, I always try to give my help with the little things I'm able to do, but I'm missing at least two most important characteristics, both highly needed for this task:
English is not my mother tongue (so I need a lot of time to understand what I read, and even more to try to write something intelligible),
and, most important,
I have not the culture needed to be able to modify the wiki ssc, sorry.

Given I’m trying to give suggestions, I see that in the last months there have been a lot of patches, SVN, beta releases and so on, chasing each other at very short intervals, and this produces a lot of confusion in many people, I think.
It looks like, instead of officialising the already established new stuff, you and the other developers are going on and on searching for new improvements.
I beg your pardon Chris, I'm and old man, so be patient with me, please, but I feel that following all Celestia partial and beta improvements is becoming harder and harder as time goes by, given the missing of clear and SIMPLE explanations on how to apply them.
We have no more the time we had previously, between one release and the other, that allowed most of us to digest innovations, and to learn to use and appreciate them.
I'm sure that most of the new stuff is not used by most of people, due to the increasing difficulties to learn to use it.
Have you got seen how many people are still using older releases?
Allow me to remember what a high school professor told me many many years ago:
“...the best project, if poorly documented, will always be overtaken by another that, even if of lower quality, is very well documented”.
As I told, this is my feeling, but I would like that at lest once the silent people, i.e. the thousands of Celestians that never or very rarely write in the forum, would change their way of life, and may tell us if I’m wrong or right.
Bye and, as always, a lot of appreciation for all what you and all the other developers are doing to make Celestia better and better.
Friendly

Andrea

[BobHegwood]

Actually Bob doesn't need to study anything. It' s enough for him to use the following code in his ssc file:

Code: Select all

"Mars Pathfinder" "Sol/Mars"
{
Class "spacecraft"
Mesh "pathfinder.3ds"
Beginning "1997 07 04"
Radius 0.00546
LongLat [-33.52 19.31822 0.00139]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

"Sojourner Rover" "Sol/Mars"
{
Class "spacecraft"
Mesh "sojourner.3ds"
Beginning "1997 07 04"
Radius 0.00070463
LongLat [-33.5198 19.31822 0.00064]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}


Paul

Thanks to you ALL for your help here... I used to be able to understand this stuff, but my age, my health, and my general Brain-Dead condition just prevents me from keeping up as quickly as I would like to do.

Many thanks to you Paul, (and to you too Andrea) for all of your help here.
I believe that I now have a handle on the coding needed here.

Again, many thanks to you all. Much appreciated by this old fool.

As an aside to Andrea, I have also added some small bits of information to the Wiki pages, but my primary responsibility now lies in testing and reviewing add-ons (along with Ulrich) for the Motherlode. This seems to be taking quite a bit of my time now, or I would offer my services on the Wiki once again. At any rate, my primary expertise lies in converting scientific gobbledy-gook into English so that your normal, average Bozos can make some sense of it too. You know that even us Brain-Dead types can still have an interest in the exploration of space. Besides, you may wish to note that we are also the people who pay for this exploration, so you may wish to keep that in mind as well while I'm asking stupid questions.

Thanks again, Bob

[BobHegwood]

Bob, I tried it with Celestia 1.5.0, and it equally works flawlessly, provided that I slightly changed the semimayor axes, as follows:

"Mars Pathfinder" "Sol/Mars/ "
SemiMajorAxis 3396.003

"Sojourner Rover" "Sol/Mars/ "
SemiMajorAxis 3396.0028

with Mars having

"Mars" "Sol"
Radius 3396 # equatorial

Look at the image.

Bye

Andrea

Yes, I tried this also, but I'm afraid that my judgment with the SemiMajorAxis element was what was throwing me off.
Not to worry though... I have learned something new, and Paul's code works flawlessly on my system. Heck, I even placed the Sojourner in a different position so that it has moved around a bit.

Many thanks to you and Paul. Much appreciated once again.

[Cham]

This works perfectly in Celestia 1.5.1 and doesn`t have any hacks.

Code: Select all

"Mars Pathfinder" "Sol/Mars"
{
Class "spacecraft"
Mesh "pathfinder.3ds"
Beginning "1997 07 04"
Radius 0.00546
LongLat [-33.52 19.31822 0.00139]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

"Sojourner Rover" "Sol/Mars"
{
Class "spacecraft"
Mesh "sojourner.3ds"
Beginning "1997 07 04"
Radius 0.00070463
LongLat [-33.5198 19.31822 0.00064]

Orientation [160.68178 1 0 0]
RotationOffset 192.485

Albedo 0.50
}

This works great with the latest SVN Celestia. We also need something similar for MER-A (Spirit) Rover, MER-B (Opportunity) Rover, Viking 1 and Viking 2. Anyone have the SSC codes for these ?

[ANDREA]

...Many thanks to you and Paul. Much appreciated once again.

You are welcome, Bob.
Bye

Andrea

[ElChristou]

I think I agree quite a bit with Andrea; what would be great is to create some sort of testing addons depending on which class the new features are for. Those simple addons could be a good way to compare/understand how a new fonction work. Ideally we should be sure that the new function get a good tutorial before more work. Ok, I can understand perfectly that this way of work would be really boring for the devs who understand perfectly what they are doing. Now being sure a lambda user can understand and use correctly Celestia would be the real achievement of the spirit of sharing knowledge, or not?

I suppose there is a real work to do about the future of Celestia. Recently as Andrea point out, Celestia become much more complex and professional and lose quite of it's universality... (note that by universality I'm talking about the possibility to use it by everybody). How to reverse this with all the new features and the ones to come? Again the basic questions; what is Celestia; what public is the target, etc... Not easy...

[ajtribick]

There's also the issue of the outdated and slightly haphazardly-organised documentation distributed with the Celestia itself, e.g. devguide.txt which is 6 years old; the README file contains an outdated/incorrect description of the stars.txt file format, etc.

[selden]

Recently as Andrea point out, Celestia become much more complex and professional and lose quite of it's universality... (note that by universality I'm talking about the possibility to use it by everybody). How to reverse this with all the new features and the ones to come? Again the basic questions; what is Celestia; what public is the target, etc... Not easy...

Please remember that the old ways of doing things still work, although the change in where the Solar System is located breaks old URLs. I agree that a tutorial style of documentation probably would help more people understand the new features. However, it really would be a book-length project. It probably would be appropriate for a new WikiBook to be started to do this.

[BobHegwood]

This works great with the latest SVN Celestia. We also need something similar for MER-A (Spirit) Rover, MER-B (Opportunity) Rover, Viking 1 and Viking 2. Anyone have the SSC codes for these ?

Not to point out the obvious here, but all you really need are the longitude and latitude coordinates, and of course the appropriate model files. This code is simple to modify even for me. I haven't gotten around to the models you're looking for yet, but if I find them, I'll place a post here.

Thanks, Bob

EDIT: Just FYI, the Viking landers and the old SSC file can be found on the ML HERE. Shouldn't be too much work to revise the SSC as I did (with Paul's help) for the Pathfinder and Sojourner models. Have posted my first attempt below.

Code: Select all

"Viking 1" "Sol/Mars"
{
   Class         "spacecraft"
   Mesh            "Viking.3ds"
   Beginning         "1976 07 20"
   Radius         0.0025
   LongLat         [ -48.222 22.697 0.00139 ]
   Orientation      [ 160.68178 1 0 0 ]
   RotationOffset      180.105
   Albedo         0.50
}
#The Viking 1 Lander touched down in western Chryse Planitia ("Golden Plain") at 22.697° N latitude and 48.222° W longitude at a #reference altitude of -2.69 km relative to a reference ellipsoid with an equatorial radius of 3397.2 km and a flatness of 0.0105 #(22.480° N, 47.967° W planetographic) at 11:53:06 UT (16:13 local Mars time).

This looks to be fairly accurate, but since I do not know exactly what I'm doing here, there could be some minor errors. This code does place the Viking 1 lander in its approximate location and with a fairly level appearance on the surface of Mars. Hope this helps. Thanks, Brain-Dead Bob

[BobHegwood]

I'm getting a bit closer to the ideal view of the Viking 1 Lander. The code I'm using now is listed below.
Hope this helps, but - again - I really don't know what the hell I'm doing (as usual). All I know is that this
code displays the Viking 1 Lander in a manner pleasing to me on my system.

Code: Select all

"Viking 1" "Sol/Mars"
{
   Class         "spacecraft"
   Mesh            "Viking.3ds"
   Beginning         "1976 07 20"
   Radius         0.0025
   LongLat         [ -48.222 22.697 0.00139 ]
   Orientation      [ 160.68178 1 0 0 ]
   RotationOffset      176.0105
   Albedo         0.50
}
#The Viking 1 Lander touched down in western Chryse Planitia ("Golden Plain") at 22.697° N latitude and 48.222° W longitude at a #reference altitude of -2.69 km relative to a reference ellipsoid with an equatorial radius of 3397.2 km and a flatness of 0.0105 #(22.480° N, 47.967° W planetographic) at 11:53:06 UT (16:13 local Mars time).

Thanks, Brain-Dead