Problems with Markers?

[Bob Hegwood]

Sorry, this question is more or less for Selden or Chris...

I'm in the process of re-writing the cel script for the Jupiter Tour, and for
the life of me, I can't understand what is happening with the markers on
Jupiter's moons.

When I move from Amalthea to Io, for example, Io shows up with the
red-diamond marker on it whether I want it there ot not. I have tried:

renderflags {clear "markers"}
unmark {object "Sol/Jupiter/Io"}
renderflags {set "markers"}

prior to going to Io, but to no avail. Is there something else going on here
that I need to know about?

I don't encounter this problem with other planetary tours, so I'm simply
at a loss to understand what's going on here.

Any advice would be appreciated.

Thanks, Bob

[nigel]

I am a total newbie to this prog (innit amazing?) but saw the same thing you describe in the (latest?) cassini script, an extra red marker. Can't see what it is supposed to be marking but it could help you to know, if you don't already.
Sorry can't be more informative, as I said, total newbie and learning..
Nigel

[Bob Hegwood]

Sorry can't be more informative, as I said, total newbie and learning..

Thanks for the information, Nigel. Like I said, I'm simply at a loss when
it comes to this problem. Nothing I've tried will fix it thus far, but I do
appreciate the help.

Take care, Bob

[selden]

Bob,

Can you provide a copy of your new tour?

I just ran through the "complete" tour that's available by way of the Motherlode and didn't see any marker on Amalthea or elsewhere, except for the green ones drawn by the script.

Maybe it's because I typed a ctrl-K before I ran the script, though, to make sure Markers were turned off ahead of time. And I'm using Celestia v1.4.0pre5.

[Bob Hegwood]

Selden,

The strangest thing I've seen here... Apparently, I did not apply the
"renderflags" options to clear and set in exactly the right order in
the revised tour. After I reproduced the sequence of "renderflags" and
"unmark" commands I used in the first script, the problem went away.

This is really strange though, because I was almost positive that the
sequence I was using was correct.

What can I tell you? I'm an idiot...

There also seems to be something weird about Jupiter and its moons too.
I have not had these marking problems with any other script. <shrug>
You must clear all markers, unmark ALL objects about to be marked, and
then set the renderflags to mark a location as follows:

renderflags {clear "markers"}
unmark {object "Sol/Jupiter/Io"}
unmark {object "Sol/Jupiter/Io/Prometheus"}
renderflags {set "markers"}
mark {object "Sol/Jupiter/Io/Prometheus" size 20 color [255 255 255] symbol "x"}

If this sequence is not applied exactly as shown, Io will display the red
diamond as you turn on the markers. Interesting... I also tried to use
unmarkall {}, but that causes its own problems since it disables the
markers completely.

Sorry about that, and thanks for your help.

Take care, Bob

PS - Am revising the script simply because I don't like the way it presents
itself at the moment. Too hurried, and I don't like the way the text is
presented.

[maxim]

I'm looking forward to the result!

maxim

[hank]

Bob,

I believe that when you select an object in Celestia, the object is automatically marked. So if you're selecting Io in order to go there (or for some other reason), that would cause it to be marked. Possibly that is a factor here; without seeing the complete script one can't diagnose such problems definitively.

As far as I know the "renderflags" option only controls whether markers are displayed, not which objects are marked.

- Hank

[Bob Hegwood]

Bob,

I believe that when you select an object in Celestia, the object is automatically marked...

Thanks for the advice, Hank. For some reason, though, the markers
appear to operate differently around Jupiter. Either that, or I'm
just experiencing the first or second stages of altzheimers.

At any rate, I've finally got the code operating the way it should now.

Many thanks for the help.

Take care, Bob

[Bob Hegwood]

I'm looking forward to the result!

Thanks Maxim, but don't get too excited...

I just want to slow it down a bit, and present it in a better manner.

I'm also working on the last two scripts for our Solar System. You don't
know where I can find a map of Mercury which can be correlated with
locations so that I can verify a tour of Mercury do you?

In other words, I can view the crater Beethoven on Mercury's surface,
but it looks just like any of a hundred other craters on this planet. Is
there a better map available, or some way I can verify that I'm looking
at the right location?

Will also be working on using your info pages here at some point in the
future.

Take care, Bob

[maxim]

I just want to slow it down a bit, and present it in a better manner.

And show a few more goodies? The SL9 impact sites for example?

In other words, I can view the crater Beethoven on Mercury's surface,
but it looks just like any of a hundred other craters on this planet. Is
there a better map available, or some way I can verify that I'm looking
at the right location?

So you don't want a better Mercury map, but a prelabeled one? Do I understand that right?

Will also be working on using your info pages here at some point in the
future.

Cool .

maxim

[maxim]

You may know this gazetteer with long/lat values:

http://planetarynames.wr.usgs.gov/mercury/mercTOC.html

This will help you a bit to verify positions:

http://www.m31.spb.ru/astronomy/solar_system/mercury/map.htm
http://www.enchantedlearning.com/subjects/astronomy/planets/mercury/mercurymap.shtml

maxim

[selden]

Chris created some extensive catalogs of locations on planetary surfaces, more than are included with Celestia. They're available at
http://www.shatters.net/~claurel/celestia/files/locations/

[Bob Hegwood]

So you don't want a better Mercury map, but a prelabeled one? Do I understand that right?

Hmm...

Maybe I do. That's not quite what I meant, but perhaps that's what I need
here. The problem is that there are a wide variety of Mercury textures
available, but I'm having difficulty trying to ascertain which one is correct.

Surely they're not ALL correct, because each texture identifies a different
feature for what should be a simple crater. <shrug> The crater identified
on one map shows up as a completely different crater on another map.

I'm obviously just confused here, but I'll get it sooner or later.

Thanks, Bob

[Bob Hegwood]

Chris created some extensive catalogs of locations on planetary surfaces, more than are included with Celestia. They're available at
http://www.shatters.net/~claurel/celestia/files/locations/

Thanks again, Selden, but I have the location files. As I mentioned
above to Maxim, I just can't seem to correlate the features from one
texture map to another.

Take care, Bob

[selden]

Bob,

Sorry, I misunderstood.

One problem may be that the maps of Mercury that are readily available for use with Celestia aren't very good.

For example, the maps of Mercury by John van Vliet that are on the Motherlode are offset by 20 degrees from the correct position, while Jens' maps seem to me to have a lot of imaginary topology. The maps included with Celestia are aligned properly, but are, ummm, extremely crude.

You might want to include your own map of Mercury. A reasonably accurate one is available at http://maps.jpl.nasa.gov/pix/mer0muu2.jpg

Unfortunately, it does include relief shading and needs to be rescaled for use with Celestia, but at least it is aligned properly and the major features are easily seen.

[maxim]

You surely switched on the lok-mask (limit of knowledge) to avoid filled in doublettes to confuse you. AFAIK only about 50% of mercury is really mapped.

maxim

[Bob Hegwood]

For example, the maps of Mercury by John van Vliet that are on the Motherlode are offset by 20 degrees from the correct position, while Jens' maps seem to me to have a lot of imaginary topology. The maps included with Celestia are aligned properly, but are, ummm, extremely crude.

Selden,

You have explained precisely why I'm having difficulty here.

Is there anything you don't know? Thanks again for your
help. I'll see if I can make sense out of all these textures. Thanks also
for the "real" map. When will Messenger give us real images again?

Hope I'm still alive for that.

Take care, Bob

[Bob Hegwood]

You surely switched on the lok-mask (limit of knowledge) to avoid filled in doublettes to confuse you. AFAIK only about 50% of mercury is really mapped.

Yes, I surely did...

Thanks, Bob

[selden]

Bob,

If all goes well, the first pictures will be sent back during the first flyby in January, 2008. There'll be another flyby in October, 2008, and again in September, 2009. It'll go into orbit in March, 2011.

For details, see http://messenger.jhuapl.edu/the_mission/mission_design.html