Project based organizations indeed, originally in the chemical and oil industries, construction industry, now more broadly engineering and technology - anywhere where there is a need for a strong disciplinary base to be maintained alongside a strong regional or customer facing specialism, and a need for multidisciplinary teams to form for complex product or big project purposes - like a moonshot....
In any organization where activity needs to be organized in two dimensions, matrix form is or can be, used. Matrix organization can be found in universities, for example, in colleges of agriculture where both basic research and industry-oriented groups need to be formed. IBM for many years had the quintessential matrix organization, shifting from product to customer to region. In fact, in some situations, more than one matrix is used.
The matrix structure is the only structure that allows a subordinate to report to more than one boss .This structure imposes the functional structure on the product or geographic structure.It is popular with universities and high-tech organisations