map-plane: Placing a small map on a planet

[selden]

With some hacking and slashing of one of the cubic panoramas, I've created a flat square that can be used to hold a small map (or collection of maps) tangent to the surface of a planet.

More information is available at http://www.lns.cornell.edu/~seb/celestia/map-plane.html

The Addon's Zip file is available at http://www.lns.cornell.edu/~seb/celestia/map-plane.zip

Here's a picture of it in use, showing Cornell's "North Campus Natural Areas".

[Ptarmigan]

Hi Selden,
I got a "404:not found" from the zip file link.
The picture link works OK though.

Malcolm.

[selden]

oops. sorry. It's there now.

[Guest]

Hi Selden,

I tried modifying your ssc file to place an aircraft circling above a location. I made the map object invisible also with the aircraft orbiting it. However the plane of the orbit was not stable and rotates. Have you any ideas how to keep the orbit plane tangential to the ground.

[selden]

Anonymous Guest,

Sorry, I'm really not that good with celestial mechanics: Grant Hutchison is our local expert and is the original author of the "place an object" SSC file. See http://www.lns.cornell.edu/~seb/celestia/hutchison/defined_locations-130.html

However, I think your problem may be that the orbital plane of your airplane is not changing. Rather the Earth is rotating under it while the orbital plane you've defined for the airplane is staying fixed relative to the rest of the universe.

My understanding, which may be defective, is that to correct for this you would have to specify a precession of the airplane's orbit. Unfortunately, Celestia currently does not implement precession.

At any rate, it would help if you posted a copy of the SSC file you're using.

[bcelestia]

Hi Selden,

Thanks for the reply.

I have a very nice model of the Statue of Liberty. My
plan was to place in in situ with a small aircraft
circling it.

As a first draft I used a modified version of your SSC
file for the map plane (below) to attempt to orbit an aircraft
around the edge of your map plane. To view the orbit I
look @ you map plane keeping it Edge-on on screen with
time speeded up in celestia. I confess I used trial & error
values for inclination etc of the Aircraft to try to home in
on correctish values. After many trials I threw my hat at it -
which did'nt work either.

The Radius value for the Map Plane I used is Earth Radius + 3

If you can figure out a solution or where I am going wrong (likely)
I would appreciate it.

# Aircraft

Location "Dallas" "Sol/Earth"
{
LongLat [ -96.7936 32.7858 0 ]
Size 10
Type "City"
Importance 100
}

"Dallas Area" "Sol/Earth" # A dummy body to provide a suitable orbit center
{
Class "invisible"

EllipticalOrbit {
Period 1e12 # Effectively stationary
SemiMajorAxis 3650.32643601 # Desired radius * sin(Latitude)
AscendingNode 280.5 # Earth's RotationOffset
Inclination 90 # Polar orbit
MeanAnomaly 90 # Fixed on Earth's rotation axis

}
}


"Flight Center" "sol/earth/Dallas Area"
{

Class "spacecraft"
Mesh "plane.3ds"
Texture "ncna-aerial-1k.*"
Radius 2.0


EllipticalOrbit {
Period 0.99726956
SemiMajorAxis 5667.28201258
MeanLongitude 183.7064
}

Orientation [ 57.2142 0 0 1 ]
RotationOffset 363.7064
}

"Aircraft" "Sol/Earth/Dallas Area/Flight Center"
{
Class "spacecraft"
Mesh "Aircraft.3ds"
Radius 0.00786
EllipticalOrbit {
Period 0.007
SemiMajorAxis 1.0
Inclination 57.21
AscendingNode 0.0
ArgOfPericenter 0.0
MeanAnomaly 32.0

}
}

[divine_vessel]

I have used the map-plane,it's good and easy to use.But I have a little promble :When I zoom out the earth I saw the the position on the earth where I placed the imagine is a white spot.I want to make it invisiable
.Ihave noticed the description in .ssc file have included the declaration "ivisiable" but it seems didn't work.

[JackHiggins]

Try

Code: Select all

Colour [ 0 0 0 ]

I think that's how you make the dot "black"

[selden]

In order to keep a model from being a bright spot when you are far away, you need to specify

Albedo 0

in its SSC file.

[divine_vessel]

thank you for advise.

[Joe]

I tried a few times, with Map plane add-on, it made Eclipse Finder frozen .

Here what it behaves:

I selected Eclipse Finder -> Compute, Celestia-1.3.2-pre7 was frozen.

Then I take of Map_plane from the add-on folder. Celestia-1.3.2-pre7 works happily.

What is the cause? please help

[Joe]

I tried a few times, with Map plane add-on, it made Eclipse Finder frozen .

Here what it behaves:

I selected Eclipse Finder -> Compute, Celestia-1.3.2-pre7 was frozen.

Then I take off Map_plane from the add-on folder. Celestia-1.3.2-pre7 works happily.

What is the cause? please help

[selden]

Joe,

It's worse than that.

I managed to get Celestia to crash while rotating around the "map plane", but I can't get it to do it reproducibly.

Also, Celestia v1.3.2pre7 is drawing it as a cube.
That's not the way I designed the model. Maybe I accidentally put the wrong model into the Addon, though.

I'll try redoing the model to see if I can persuade it to look the way it's supposed to.

[t00fri]

With some hacking and slashing of one of the cubic panoramas, I've created a flat square that can be used to hold a small map (or collection of maps) tangent to the surface of a planet.

More information is available at http://www.lns.cornell.edu/~seb/celestia/map-plane.html

The Addon's Zip file is available at http://www.lns.cornell.edu/~seb/celestia/map-plane.zip

Here's a picture of it in use, showing Cornell's "North Campus Natural Areas".

Hey Selden,

great, so there is clearly one obvious suggestion

For each of my 45000+ towns, could you please attach a little city map?

Bye Fridger

[selden]

But Fridger, all you have to do is run a perl script that downloads the maps and edits the model file!


And run Celestia v1.3.1 final.

Unfortunately, the current "map plane" addon doesn't work with v1.3.2 prereleases. SSC texture mapping changed so that the model's "transparent" protective box isn't transparent any more
I'll probably be updating the map plane to get around the problem, but not for a few weeks.

[t00fri]

But Fridger, all you have to do is run a perl script that downloads the maps and edits the model file!

...and who is providing the 45000+ maps for my Perl script?

And run Celestia v1.3.1 final.

I have no idea what version I am using, since I always checkout the latest CVS, every evening. It's just a click away.

But it's a cute idea anyway...

Bye Fridger