Affine transformations appear to not be implemented for line elements at the moment. This seems to be fixable by adding a few lines that apply the affine transformation to the start_point and end_point vectors within the getOffGridPoints function in kWaveArray.
For example, in the 2D case we currently have:
px = linspace(obj.elements{element_num}.start_point(1) + d(1)/2, obj.elements{element_num}.end_point(1) - d(1)/2, m_integration);
py = linspace(obj.elements{element_num}.start_point(2) + d(2)/2, obj.elements{element_num}.end_point(2) - d(2)/2, m_integration);
Which does not apply the affine transformation. If we replace these lines with the following:
start_affine = obj.affine(obj.elements{element_num}.start_point);
end_affine = obj.affine(obj.elements{element_num}.end_point);
px = linspace(start_affine(1) + d(1)/2, end_affine(1) - d(1)/2, m_integration);
py = linspace(start_affine(2) + d(2)/2, end_affine(2) - d(2)/2, m_integration);
Then the transformation appears to work.