I don�t have a program for you but here is what you need:
Since this is a diagram to represent a direction and magnitude, and not
to actually determine coordinates on a spheroid, as in a survey, you can
use a simple coordinate geometry functions to determine points as if
they were on a regular grid (plane geometry).
You might want to scale the distance for illustration purposes. For
example if your values are in feet per minute you might have relatively
large values such as 300 fpm. You might not want to display lines 300
feet in length on the map, so you might scale them differently to feet
per second or some other value you consider illustrative of the data.
Known:
1) The coordinates of point "A" in some coordinate system, say decimal
degrees. Easting (X), Northing (Y)
2) Bearing
The bearing must be converted to Radians.
When you say Bearing what do you really mean? Bearing or Azimuth?
2.a) Convert Bearing (N 45 degrees W) to an Azimuth (315 degrees)
You want your bearing in azimuth degrees (0 - 360 degrees)
2.b) Convert your Azimuth to Radians
Radians = Azimuth_degrees * pi / 180
Solve for coordinate B (The end of the line):
Easting_B = easting_A + distance * sin(Radians)
Northing_B = northing_A + distance * cos(Radians)
You now have the two coordinates necessary to draw the line A,B
-----Original Message-----
From: Simon Roy [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 31, 2003 08:28 AM
To: Mapinfo-L
Subject: MI-L Drawing lines from speed and bearing values
Hi all,
I have a point table. To each point is attached values of speed
and
orientation of the current of a river. I'm looking for MB program or
code
that will draw proportional lines based on the speed value and oriented
according to the bearing value of each point.
Thank you!
Simon Roy
-----------------------------------------
GIS Specialist
Carto-M�dia, Environnement Illimit� inc.
tel.:514-849-7281
fax.:514-849-6770
-----------------------------------------
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