In this paper, a novel sphere-tree generation method used for collision detection is proposed. Using existing consumer-level graphics cards and its programmable graphics processing units (GPU) a sphere-tree is constructed in real-time inside an animation. This guarantees that no construction or loading of a precomputated hierarchy is required. With our method, core memory is managed in an efficient manner, allocating and releasing memory space as necessary. By this, out-of-core techniques can perform better in real-time situations. The animation tests maintain an above the average performance and the collision detection is fast and efficient.