String pathy = path+"dy";
builder.writeDeltaFile(0, pathx);
builder.writeDeltaFile(1, pathy);
gridParams.parameter("X_difference_file").setValue(pathx);
gridParams.parameter("Y_difference_file").setValue(pathy);
MathTransform mt = (new ProviderFile()).createMathTransform(gridParams);
MathTransform mtOriginal = builder.getMathTransform();
float[] wp = ( float[] )(((WarpGridTransform2D)mt).getParameterValues().parameter("warpPositions").getValue());