PC-AffineTrans

PC-AffineTrans (free)

PC-AffineTrans is a tool for precise coordinate transformations from one coordinate reference system to another.

The transformation is performed as an Affine transformation, where a two sets of matched 3D points are used as a basis for calculation of transformation parameters. This kind of transformation is also often called Helmert Transformations.

Nine transformation parameters are calculated from the two sets of matched points. These parameters can then used to transform  the pointcloud. Or, the individual parameters can be modified, to change amount of:
  • translation
  • rotation and
  • scaling
It is possible to test the effect of changed parameters when applied on the set of matched ground control points (gcp's) before the transformation parameters are applied on the whole pointcloud.

Screenshot




Input file-formats
Three sets of input-files are required to run the software:

1. Matched GCP's (-from coordinate system):

 Id X Y Z (text optional)
 1 -7.20917 6.84926 -30.54065
 2 -6.75404 -3.44483 -21.48141
 3 -5.03028 -3.79336 -21.00271

2. Matched GCP's (-to coordinate system):

 Id X Y Z (text optional)
 P1 6631220.996 576459.562 195.400 (Text 1)
 P2 6631100.920 576582.962 186.500 (Text 2)
 P4 6631076.174 576380.777 190.000 (Text 3)

3. Points to be transformed:
(Note: R G B colums are not affected by the transformation)

 X Y Z (optional additional columns)
 -0.2816473 0.3387736 -0.760989 57 60 57
 -0.3872102 0.4379584 -1.027567 74 64 65
 -0.7371762 0.1972285 -1.433231 213 153 82
 -0.8749919 0.0170119 -1.432256 164 105 32
 -0.4446898 0.431412 -1.279967 49 52 49
 -1.170961 0.03090006 -1.415155 139 85 32
 -0.4143303 0.4674045 -0.969249 41 44 32
 -0.261767 0.2294519 -0.8984499 65 60 57
 -0.4046374 0.4861406 -1.223415 65 60 65

Speed and performance

The software is applying a new transformation method, fully managed code (not depending on any software librarys) and is much faster then comparable software.

Processing speed will offcourse vary depending on hardware and software configuration. On a standard laptop running windows XP the software can be expected to transform at least 50.000  points pr. second.

 

Free version
This version is free for personal non-commercial and non-governmental use. It is however restricted to transformation of 200.000 points at a time.
The software is still under development. Please report errors and express views on the software at www.uavmapping.com/forum

For a non-restricted commercial licence, please contact: Jørn Anke / UAVMapping.com for information. e-mail: mail@uavmapping.com

 

UPDATE 2011-08-20

The source code of PC-AffineTrans will be made avaliable to anyone who wants to include the functionality in any open source projects. A reference to the origin of the source code must however be made.

Download (unrestricted copy)


Keywords

9-parameter 3D affine transformation, solution of polynomial system, symbolic solution, Dixon resultant, early discovery factors, reduced Groebner basis, homotopy, numerical Groebner basis, global minimization, genetic algorithm.