[Therion] Georeferenced PNG export problem

Evaristo Quiroga eqr at ecgracia.com
Mon Mar 26 13:25:55 CEST 2018


The reverse engineering is not with the PDF. Martin do a good job here 
putting in all the therion output pdf a comment with the reference. You 
only have to open the file and search "thCalibrate". You found the next 
text:
/
///thCalibrate0 (X=-22.16017pt, Y=260.12132pt, L=-0.3641990570, 
F=42.2992656650) //
///thCalibrate1 (X=1921.38345pt, Y=199.8752pt, L=-0.3608862211, 
F=42.2991894208) //
///thCalibrate2 (X=3864.92708pt, Y=139.62904pt, L=-0.3575733981, 
F=42.2991130810) //
///thCalibrate3 (X=-0.2183pt, Y=967.96619pt, L=-0.3641616744, 
F=42.3001613659) //
///thCalibrate4 (X=3886.86893pt, Y=847.47388pt, L=-0.3575359218, 
F=42.3000087771) //
///thCalibrate5 (X=21.72351pt, Y=1675.81102pt, L=-0.3641242900, 
F=42.3010570667) //
///thCalibrate6 (X=1965.26714pt, Y=1615.56487pt, L=-0.3608113605, 
F=42.3009808177) //
///thCalibrate7 (X=3908.81078pt, Y=1555.31871pt, L=-0.3574984437, 
F=42.3009044731) //
///thCalibrate8 (X=1943.32529pt, Y=907.72003pt, L=-0.3608487917, 
F=42.3000851193) //
///thCalibrate (HS=3913.97253pt, VS=1573.34683pt, HD=546.7244489428)/

All the information is here:  pdf coordinates (X,Y), real coordinates 
(L,F) and the pdf width (HS) and height (VS).

You only need know the width and height from the generate PGN, and you 
have all the data to do the calculation.

The reverse engineering is to understand the ".map" format and found in 
the tcl file (mapcalc.tc) the equations to do the conversion.

Regards,

Evaristo.


El 26/03/2018 a las 12:57, Nikita Kozlov via Therion escribió:
> You can export 2 PNGs one with grid to put GCPs on, and second PNG 
> without grid, but exactly same size (in pixels).
> And use GCPs put on first grid-equipped PNG to georeference second 
> "grid-free" PNG.
>
> Grid is used only to get pixel coordinates.
>
> Dealing with pdf and 'reverse engineering' for me seems a bit 
> complicated stuff,
> since in addition to 6 georeference parameters, you need to deal with 
> scale and so on,
> so I'd rather used quick and dirty solution with grid and rasters.
>
>
>
>
> _______________________________________________
> Therion mailing list
> Therion at speleo.sk
> https://mailman.speleo.sk/listinfo/therion


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