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# Coordinate transformation

## Coordinate transformation

I would like to make coordinate transformation via Helmert or Afin method. It shoul be used for any civil 3d objects and point files. Transformation matrix and point pairs should be saved and re-used any time.

Mentor

Cemil,

Dave

Points

FIRST SYSTEM(SOURCE)

SECOND SYSTEM(TARGET)

y

x

Y

X

N.1

545430.463

4351434.836

545408.237

4351252.452

N.2

445865.410

4321096.840

445843.458

4320914.823

N.3

415295.590

4183714.550

415274.203

4183533.151

N.4

424726.460

4227139.000

424704.990

4226957.195

N.5

409159.410

4292887.300

409137.693

4292705.159

N.6

410387.800

4292275.410

410366.064

4292093.342

N.7

412089.110

4293697.380

412067.373

4293515.364

N.8

412454.580

4289205.300

412432.975

4289023.387

N.9

412762.560

4342802.110

412740.812

4342619.838

N.10

413090.820

4295316.740

413069.013

4295134.744

Hello Dave,

Thank you so much for your attention. The points on the list above, they are
same points on earth however they are on different coordinate systems. This
coordinates or objects can be transformed to each other system by using
Helmert similarity transformation, Affine Transformation or Projective
transformation. Coordinate pairs or transformation parameters can be saved

Please take look matrix calculation for Helmert Similarity Transformation at
below.

x1

- y1

y1

x1

..

..

X1

VX1

..

..

a

Y1

VY1

Matrix A(2nx4)=

..

..

b

..

..

..

..

Matrix X(4x1) =

c

Matrix L(2nx1)=

..

Matrix V(2nx1)=

..

..

..

d

..

..

xn

- yn

Xn

VXn

yn

xn

Yn

VYn

n:Point umber

ax1-by1+c=X1+Vx1

ay1+bx1+d=Y1+Vy1

N=ATPA

..

n=ATPL

..

X=N-1n

P:Unit Matrix

..

..

axn-byn+c=Xn+Vxn

ayn+bxn+d=Yn+Vyn
Mentor

Cemil,

From the Help Section:
"You can define your own transformations based either on a grid file or on parameters you specify."

http://help.autodesk.com/view/CIV3D/2016/ENU/?guid=GUID-CBFAC20A-F512-4D52-8663-D46DCAA83544

Dave

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