Projective Geometry and Line Geometry

This book is a contribution to visual geometry, mainly three-dimensional projective geometry and line geometry. There may be no better way to get deeply involved in spatial geometry than in exercising the skills of visual representation by the means of synthetic geometry. Thus I have adopted the synthetic method, which forms a characteristic feature of this presentation. In addition, I outline a special approach to Euclidean geometry: this ever present geometry is not conceived as a primitive space form but is consistently treated as a certain kind of limiting case of general projective metric geometry. Not only can this be of practical importance, but it will particularly refine and clarify the logical skills and the basic concepts of geometry. In addition, it helps one keep an open mind with respect to new ideas and techniques which might be of significance in the future.