We propose SCom Tree, a compact representation for geometry based on Signed Distance Fields (SDF), which outperforms previous approaches in both size and quality while maintaining comparable rendering speed. Our representation employs the concept that many surface regions are similar to each other up to a linear transformation, and only a small fraction of them can be stored to represent the whole 3D model. At the top level, we use BVH trees to accelerate ray tracing and efficiently cull empty space. The BVH leaves store octrees, with nodes referencing surface regions, each represented by a small 3D grid (brick) and transformation. The transformations themselves are a limited set of rotations and translations that are encoded with a short index. SCom Tree supports a continuous level of detail that enables efficient streaming and performance control at far distances, making our method particularly useful for rendering large 3D models with ray tracing.