This paper presents a novel approach to implementing dynamic LOD on GPU. For our purpose, a quadtree structure is created based on seamless geometry image atlas, which is a 3D surface representation in parameter space by combining the features of geometry images and poly-cube maps. All the nodes in the quadtree are packed into the atlas textures. There are two rendering passes in our approach. In the first pass, the LOD selection is performed in the fragment shaders. The resultant buffer is taken as the input texture to the second rendering pass by vertex texturing, and thus the node culling and triangulation can be performed in the vertex shaders. Our LOD algorithm can generate adaptive meshes dynamically, and can be fully implemented on GPU. It improves the efficiency of LOD selection, and alleviates the computing load on CPU.