Rodamiento entre dos puntos

Question

He estado usando el paquete GEOPY, lo que hace un gran trabajo, sin embargo, algunos de los resultados que obtengo son inconsistentes o vienen con un desplazamiento relativamente grande, sospecho que el problema reside con mi cálculo de cojinetes:

def gb(x,y,center_x,center_y):
dx=x-center_x
dy=y-center_y
if ((dy>=0)and((dx>0)or(dx<0))):
    return math.degrees(math.atan2(dy,dx))
elif (dy<=0)and((dx>0)or (dx<0)):
    return (math.degrees(math.atan2(dy,dx))+360)
else:
    return (math.degrees(math.atan2(dy,dx))+360)%360

Necesito calcular el cojinete, S.T.Center_x y centro_y son el pivote.Posteriormente, uso GOOPY para invertir el ingeniero de la coordenada GPS:

latlon = VincentyDistance(miles=dist).destination(Point(lat1, lon1), bearing)

¿Puede alguien apuntarme a lo que podría estar haciendo mal?

Answer 1

Can anyone point me to what might i be doing wrong?

1. Not showing an example of your "inconsistant or come with a relatively large displacement" results nor your expected results; consequently answerers must rely on guesswork.

2. Not saying what units your input (x, y, etc) is measured in, and how you get the dist used in the destination calculation. I'm assuming (in calculating bearing2 below) that positive x is easting in miles and positive y is northing in miles. It would help greatly if you were to edit your question to fix (1) and (2).

3. A coding style that's not very conducive to making folk want to read it ... have a look through this.

4. In school trigonometry, angles are measured anticlockwise from the X axis (East). In navigation, bearings are measured clockwise from the Y axis (North). See code below. For an example of bearing in use, follow this link, scroll down to the "Destination point given distance and bearing from start point" section, notice that the example is talking about bearings of about 96 or 97 degrees, then click on "view map" and you will notice that the heading is slightly south of east (east being 90 degrees).

Code:

from math import degrees, atan2
    def gb(x, y, center_x, center_y):
        angle = degrees(atan2(y - center_y, x - center_x))
        bearing1 = (angle + 360) % 360
        bearing2 = (90 - angle) % 360
        print "gb: x=%2d y=%2d angle=%6.1f bearing1=%5.1f bearing2=%5.1f" % (x, y, angle, bearing1, bearing2)

    for pt in ((0, 1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1),(-1, 0),(-1,1)):
        gb(pt[0], pt[1], 0, 0)

Output:

gb: x= 0 y= 1 angle=  90.0 bearing1= 90.0 bearing2=  0.0
gb: x= 1 y= 1 angle=  45.0 bearing1= 45.0 bearing2= 45.0
gb: x= 1 y= 0 angle=   0.0 bearing1=  0.0 bearing2= 90.0
gb: x= 1 y=-1 angle= -45.0 bearing1=315.0 bearing2=135.0
gb: x= 0 y=-1 angle= -90.0 bearing1=270.0 bearing2=180.0
gb: x=-1 y=-1 angle=-135.0 bearing1=225.0 bearing2=225.0
gb: x=-1 y= 0 angle= 180.0 bearing1=180.0 bearing2=270.0
gb: x=-1 y= 1 angle= 135.0 bearing1=135.0 bearing2=315.0

Answer 2

I'm not quite sure what you're trying to do in your code,but I do see some oddities that may need to be cleaned up.

1. You test for dy<=0 after you test for dy>=0 in the conditional before. What should your code do if dy==0 and dx==0.
2. Your test ((dy>=0)and((dx>0)or(dx<0))) is equivalent to (dy>=0 and dx!=0), is this what you intended?
3. You are basically doing the same thing in all of your conditionals. Couldn't return math.degrees(math.atan2(dy,dx))+360)%360 work in every scenario? In that case, you wouldn't need to use your if statements anyway.