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I'm using QGIS to analyse some flight tracks which were produced using a different software. Now when they are on QGIS the reference point of everything is on 0,0 which is the aerodrome reference point.

But in real world this aerodrome reference point is a value in Easting and Northing. i.e. Easting=286499.025 Northing=6230965.204, so the everything else (runway ends, tracks points should be exactly as they are in the real world)

I did some research and found the Vector Affine Transformation plugin. Now using this how can I move everything to the reference point of Easting=286499.025 Northing=6230965.204 Easting = X and Northing = Y.

I'm having trouble understanding the plugin's matrix.

enter image description here

  • Note that easting and northing are projected coordinate values. Be sure you have the correct CRS set that you're trying to transform the data to. Have you looked at the plugin's help? The matrix allows for accounting for a rotation, which you may not need (and couldn't use if you only have a single point with no angular reference). Essentially, rather than an affine transformation, it sounds like you just want to do an absolute (from 0,0) move of all your features to your easting/northing coordinates. – Chris W Feb 25 '15 at 23:24
  • You're spot on. On autocad what I do is select all>move>set 0,0 > move to > desired easting and northing. I have set the CRS to MGA94Z56. Can QGIS's move option be used to do this? i.e snap to 0,0 and then input the desired x and y coords? thanx – Dilla Feb 25 '15 at 23:47
  • I don't know about QGIS - I know ArcGIS' Move command allows for this. Related: gis.stackexchange.com/questions/13433 – Chris W Feb 26 '15 at 0:29
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As indicated in my answer to How to compute parameters for QGIS Affine transformation?, you can do it after you recognize the different parameters of the matrix.

Parameters are:

a: Scale X 
e: Scale Y
d: Rotation X
b: Rotation Y
c: Translation X
f: Translation Y

enter image description here

So, you should be able to move your layer by setting c and f parameters with your x and y values, i.e., c=286499.025 and f=6230965.204.

Special attention must be given to setting the map reference system beforehand. Hopefully, both the RS you set and your original data are in the same unit (e.g., meters), otherwise you might need also to apply a scale factor to your data.

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    Great! This picture explains it a lot. I was having trouble understanding the readme with the plug in. – Dilla Feb 26 '15 at 0:43
  • Right, I agree it's not easy to figure that out. – Germán Carrillo Feb 26 '15 at 0:44
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    YES!!! just came back to say thanks. I wanted to check whether the relocation is correct. So I imported a new layer with correct georeference which I had to do in Autocad. So my relocated layer should match up with the new imported layer and YES they do match :) I have another small question. So I have features in the layer I'm working in three different columns. op_type, rwy_id, trak_id. Other than using Filter command what's the easiest way to show/hide features. i.e. op_type = A, rwy_id = 06 trak_id = 06TA? Thanks a lot – Dilla Feb 26 '15 at 1:54
  • As to your follow-up question, I would say that's the better way to do it, using it a filter. If you need help with it or if your use case differs a bit and you want to get another result than using a Filter, please open a new question in the site. – Germán Carrillo Feb 26 '15 at 2:07

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