Fruhauf, Thomas2014-10-212014-10-2119941467-8659https://doi.org/10.1111/1467-8659.1330293Raycasting is an efficient, but computation-intensive technique for the direct rendering of volumetric data. Nonregularly structured volume data is produced in a variety of applications, such as numerical simulation, ultrasonic inspection, or seismic measurement. Unfortunately, in raycasting nonregulary structured grids, sampling data along the rays is even more computation-intensive. One idea might be to resample the data onto a regular grid for further processing. It is shown, that resampling typical grids results either in extreme sub- sampling of the most interesting areas or in data sets too huge to handle. Additionally, no better hardware will overcome the fact that all topology and context information is lost through resampling. Therefore, dedicated algorithms for the raycasting of nonregularly structured volumes are required.We present a new approach for this task, which is based on sending rays through the computational space of a nonregular grid, instead of conventionally raycasting the physical space. This technique overcomes the difficulties in sampling data along the rays, since the computational space is regular by definition. The paper outlines the mathematical operations of this technique as well as its embedding in a rendering algorithm. We have implemented the new raycasting strategy as a module of our interactive visualization system, providing the users with an additional tool for the efficient exploration of their data.10.1111/1467-8659.1330293293-303