We present EchoScene, a dual-branch diffusion model that is able to generate and manipulate 3D scenes with given scene graphs. In both branches, each node is allocated with a denoising process to support graphs with indefinite nodes and edges. 

EchoScene encapsulates an information echo scheme to make every node in the graph exchange denoising data at each time step along the process, steadily achieving global graph constraints.

EchoScene leverages a dual-branch diffusion model to create 3D scenes from scene graphs. Within this model, each node undergoes a denoising process in both branches. These processes incorporate global state awareness by utilizing layout and shape "echoes" - depicted as waves in various colors - facilitated by an information exchange unit, represented by a grey block, throughout the denoising phases.

Inside the dual-branch architecture, there is an information echo scheme that makes the whole pipeline functional. 

In the layout branch (Figure. A), information echo becomes "layout echo." A layout echo happens at each denoising step. Every node sends its current diffused bounding box, relation embedding, and current time to the layout exchange unit Ul to perform message passing and feature aggregation. The aggregated features for each node then echo back to their own denoising process, making the denoised bounding boxes aware of other nodes' geometric information.

In the shape branch (Figure. B), information echo becomes "shape echo." The dynamics of shape echo are similar to those of layout echo, except the diffused bounding boxes map to diffused shape codes. At each denoising step, shapes are aware of each other to make the global style (scene appearance) consistent.