A method for raycasting based on an irregular grid. The method includes raycasting, in a static mode, rays based on the irregular grid to generate a static image of a three dimensional (3D) volume dataset. The 3D volume dataset includes irregular grid cells based on the irregular grid. The method further includes reducing a tally of the rays to generate a reduced tally of rays based on a rendering time of the static image and an animation frame rate, and generating, in a dynamic mode, an animation of the 3D volume dataset at the animation frame rate by at least performing raycasting based on the reduced tally of rays.