I would like to perform transformation for this example data set.
I have here four pairs of adjustment points and want to transform given point coordinates from primary system to secondary system according to adjustment.
primary_system1 = (3531820.440, 1174966.736, 5162268.086)
primary_system2 = (3531746.800, 1175275.159, 5162241.325)
primary_system3 = (3532510.182, 1174373.785, 5161954.920)
primary_system4 = (3532495.968, 1175507.195, 5161685.049)
secondary_system1 = (6089665.610, 3591595.470, 148.810)
secondary_system2 = (6089633.900, 3591912.090, 143.120)
secondary_system3 = (6089088.170, 3590826.470, 166.350)
secondary_system4 = (6088672.490, 3591914.630, 147.440)
#transform this point
x = 3532412.323
y = 1175511.432
z = 5161677.111<br>
eventually, how do I compute helmert transformation parameters, shifts, rotations and scale factor?
EDIT
at the moment I try to average translation for x, y and z axis using each of the four pairs of points like:
#x axis
xt1 = secondary_system1[0] - primary_system1[0]
xt2 = secondary_system2[0] - primary_system2[0]
xt3 = secondary_system3[0] - primary_system3[0]
xt4 = secondary_system4[0] - primary_system4[0]
xt = (xt1+xt2+xt3+xt4)/4 #averaging
…and so on for y and z axis
#y axis
yt1 = secondary_system1[1] - primary_system1[1]
yt2 = secondary_system2[1] - primary_system2[1]
yt3 = secondary_system3[1] - primary_system3[1]
yt4 = secondary_system4[1] - primary_system4[1]
yt = (yt1+yt2+yt3+yt4)/4 #averaging
#z axis
zt1 = secondary_system1[2] - primary_system1[2]
zt2 = secondary_system2[2] - primary_system2[2]
zt3 = secondary_system3[2] - primary_system3[2]
zt4 = secondary_system4[2] - primary_system4[2]
zt = (zt1+zt2+zt3+zt4)/4 #averaging
Is it right way?
Best Answer
There is a python wrapper for the proj4 library. Proj4 is a commonly used library for projecting data from one system to another.
Whatever system you do use, it will most likely take the point information in the form
(lon, lat)
or(y,x)
. Just something to be aware of - I've made this mistake in the past.(I'm not familiar with the helmert transformation part of your question.)