Structured grids and some of their applications in natural sciences are discussed. The problem of their visualization and quantitative evaluation is considered and possible ways for its solution sketched. Resampling a structured grid onto a regular one is such a possible solution offering the additional benefit of enabling quantitative evaluations, too. This resampling is achieved by a preliminary tetrahedronization of the structured grid(s) and a subsequent digitalization of the constituent tetrahedrons using an adaptation of the 3D-Bresenham algorithm. Advantages and disadvantages of this approach as compared to other possible schemes are discussed. An implementation based on our open source f3d-file format for storage and transmission of volumetric data is presented, and results from applying it to real-world data shown.