[Qgis-user] Simple Georeference a .png chart

[Atanvarno]

Hi Jonathan, hi André

Thanks for your reply's!

@André: Yes, I have taken W degrees as negativ values and I also
recalculated the degrees into decimal degrees.

@Jonathan: Those two examples I have uploaded are just examples of
stand-alone charts, each for itself. Not part of any complicated area or so
and I don't want to have one chart merged over or into the other chart. Just
take this single picture, georeference it and then export it again into pdf
or tiff or so. 
Depends what you mean but yes, I don't wan't to have ANY distortion/warping
etc at all. The charts above are used in aviation and I also worked for that
company before. The points and charts are geographically and georeferenced
correct. It is all done by an own GIS programm out of databases and for
aviation purposes with moving map etc. So I don't understand then, when the
charts are already correct by variation etc, that there should be any
warping at all, since QGIS should work with same "informations" eg. 17°
variation W etc?

Maybe it helps, when I explain what I am doing, so one can figure out what I
am doing wrong:

1. Open programm (using MAC and/or WIN - shoudl not matter) - QGIS Desktop
2.4
2. "New" Project is already open with starting the programm. Standard KBS is
WGS84 set.
3. Tab RASTER > Georeferencer > Georeferencer
4. Tab FILE > Open raster > KEWR_AGC
5. Pop-Up for Coordinate Reference System: I choose WGS84: EPSG4326 > OK
6. Now I start with setting the georeference points:
    I use now for example the grid-raster of each corner to georeference it.
    a) top left: grid coordinate: N40° 42.5' / W074° 11.5'; recalculated
into decimal degrees:
        N 40.70834 / E -74.191665
    b) top right: grid: N40° 43.0' / W074° 9.6'; in decimals: N 40.716667 /
E -74.16
    c) lower left: grid: N40° 40.5' / W074° 11.0'; in decimals: N 40.675 / E
-74.183333
    d) lower right: N40° 40.5' / W074° 9.0'; in decimals: N 40.675 / E
-74.15
7. Using "Add point" tool > Crosshair over the corresponding grid > Enter
map coordinates:
    as example for top left corner I enter: X/East: -74.191665    and
Y/North:  40.70834 
    Hit "OK" and do this for all 4 coordinates.
8. Tab SETTINGS > Transformation Settings > 
    Transformation type: Polinominal 1 (as suggested)
    Resampling method: linear
    Compression: NONE
    ---
    Output raster: KEWR_AGC_modified.tiff
    Generate PDF map: KEWR_AGC_modified.pdf
    Hit "OK"
9. Toolbar: Start Georeferencing


The output is attached below. This time at least the warping looks correct.
Just like the grid is now 180° north orientated and not with the 13°W
Variation. Maybe its because of the Polinominal 1 setting as proposed. Last
time it was distorted completely... 

But the PDF map is empty... Just a white page. Would be nice if this could
also work since I hope the file size will be much less then tiff. 

Is there no way to keep the page upright as it is and have the variation
somehow included, so that the chart is not turned?

On Saturday/Sunday I will check it with Dehli Airport how it workes there. 


<http://osgeo-org.1560.x6.nabble.com/file/n5167661/KEWR_AGC_modified.png> 


Is there any plugin where I can upload .pdf files directly without
converting it into a .tiff and then load it via raster image? Since all my
charts are delivered in .pdf, this would be very helpfull.

Thanks a lot for all the help!

With best regards

Alex



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