Thanks Nikita.

First, I thought about doing it as you say. But I want an image that only has the survey and the rest is transparent, so putting the grid complicates my work.

Then I discovered that the "calibrate bitmap" option does all the work. But it's not working.
We don't need the grid because the exported Therion PDF have a comment with nine coordinates (thCalibrate) . A Xtherion tcl command (mapcal.tcl) do the calculation from the pdf coordinates to the bitmap coordinates. I am now doing inverse engineering with this file to understand the equations, to do the calculation manually.

Regards,

Evaristo.

El 26/03/2018 a las 11:32, Nikita Kozlov via Therion escribió:

For possible work-around you can export map with grid lines, and use grid lines intersection points as GCP (ground control points) with known coordinates to manually georeference your raster PNG.
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