For example, use the list of seven Location entries shown at the bottom of this message to create a test.ssc Locations file (taken from Fridgers earth_Locs file). Go to Hawaii, turn Location labels ON (&), and start lowering your altitude over the big island. All of the entries are valid, but you can't read a single one of them.
Code: Select all
Here are a Cel:// URL and Bookmark entry to duplicate my view:
cel://SyncOrbit/Sol:Earth/2003-07-27T20:49:22.01396?x=8+RFxDhlvbrGDA&y=T7jY8U0/AQ&z=DfM314J/ED8N&ow=0.008810&ox=0.776638&oy=0.619880&oz=-0.111820&select=Sol:Earth&fov=25.745911&ts=1.000000&rf=740515645&lm=-1076827510<d=0&rf=2&lm=128
"Hawaii_Locations_Problem" {
isFolder false
parentFolder ""
base [ 0.003270729422781963 1.898051194065863e-011 1.324636635384398e-005 ]
offset [ 1.182466667984383e-013 0 8.071343073068338e-016 ]
axis [ 0.776604 0.62004 -0.111517 ]
angle 3.1245
time 2452848.367478303
selection "#0/Earth"
coordsys "geographic"
}In this example, the use of different Size and Importance values has no bearing on the end result -- the closer you get, more text labels are added on top of one another. What about using the Type parameter? Well, there are four "Observatories" and three "Other" (telescopes), so that would not suffice either.
I would expect to see this "same Long/Lat entries" problem with several observatories or VLBA locations, since they can have multiple projects at the same location, just like the one in Hawaii.
To manually edit the Long/Lat values is a work-around possibility, but this would make the locations inaccurate. Doing this with a large Locations file that has been converted from a published list (such as Fridgers UNECE list -- 478KB!), would become a nightmare. Even if this was done, if the user has several Location files, of different objects, there could still be multiple entries in the same Long/Lat coordinates.
So, Celestia needs to determine if there are multiple Location entries within some range of Long/Lat values (0.01?) and if there are, place the labels in a list, instead of placing the labels in the same screen area (over each another). This is also where having a "marker" for the location would come in handy: one marker and a list of entries is easy to see.
Any other ideas?
-Don Goyette
Seven valid Hawaii locations for the Big Island:
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Location "Canada-France-Hawaii Tel. (CFHT)" "Sol/Earth"
{
LongLat [ -155.4716 19.8266 0 ]
Size 10
Importance 40
}
Location "Gemini Telescope (north)" "Sol/Earth"
{
LongLat [ -155.4666 19.8166 0 ]
Size 10
Importance 40
}
Location "Mauna Kea Observatory (NASA IRTF)" "Sol/Earth"
{
LongLat [ -155.4666 19.8333 0 ]
Size 10
Importance 40
}
Location "National Astronomy Obs. (Japan)" "Sol/Earth"
{
LongLat [ -155.4666 19.8166 0 ]
Size 10
Importance 40
}
Location "United Kingdom Infrared Tel. (UKIRT)" "Sol/Earth"
{
LongLat [ -155.4666 19.8333 0 ]
Size 10
Importance 40
}
Location "VLBA - Mauna Kea" "Sol/Earth"
{
LongLat [ -155.4577 19.8041 0 ]
Size 10
Importance 40
}
Location "W. M. Keck Observatory" "Sol/Earth"
{
LongLat [ -155.4666 19.8166 0 ]
Size 10
Importance 40
}