[aprssig] APRS Symbols- Direction/Vectoring

Robert Bruninga bruninga at usna.edu
Tue Dec 7 14:56:01 EST 2004

Agree,  All Symbols are assumed to already have the 
CSE/SPD vector.  This additional rotation is only
for the pixels of the symbol so that they dont appear
to go backwards.  Its mostly an E/W thing, because
N/S with the vector is not a problem...  Bob

>>> k4hg at tapr.org 12/7/04 12:31:41 PM >>>
On 12/7/04 at 8:22 AM Curt, WE7U <archer at eskimo.com> sent:

>Xastir has four rotations for each symbol.  We do flip pixels.
The problems I see with this are first, it only gives you 4 compass
second, it gives no indication of speed...so one of the 4 projections
must be
used as well when a station is not moving, and finally, some icons are
about the vertical axis, for example the balloon, so these can only
show two
values (east/west/stationary) and (north/south).

I much prefer the way MacAPRS has done it for the last 10 years, a
vector drawn
from the icon in the direction of travel, the length of the vector
giving an
indication of speed. Now that I think about this, I have to wonder why
I never
implemented this in plot.cgi, it wasn't even on the to-do list. It is
done now,
for example:


(At this time, this stations last report was 65 MPH, if you look at
this and
don't see a vector, there must be a new report that has no speed, try a
with motion to see the vector...)

I need to work on this a bit, the red vectors can get lost on maps
using red for


Maybe I'll let the user specify a color. This is experimental,

Steve K4HG

aprssig mailing list
aprssig at lists.tapr.org 

More information about the aprssig mailing list