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dab писал(а): То есть два параметра были отрицательные, а стали положительные:
... -0.35, -0.79 ... => ... 0.35,0.79 ...
Почему происходит смена знака?

A more complete discussion of the 3 and 7 parameter transformations can be found in the EPSG database (trf_method's 9603 and 9606). Within PROJ.4 the following calculations are used to apply the towgs84 transformation (going to WGS84). The x, y and z coordinates are in geocentric coordinates. Three parameter transformation (simple offsets):
.....

Note that EPSG method 9607 (coordinate frame rotation) coefficients can be converted to EPSG method 9606 (position vector 7-parameter) supported by PROJ.4 by reversing the sign of the rotation vectors. The methods are otherwise the same.

In EPSG there are two methods of defining the 7 parameter bursa wolf parameters, 9606 (position vector 7-parameter) and 9607 (coordinate frame rotation). The only difference is that the sign of the rotation coefficients is reversed between them.