batch_size cannot be larger than 1 in controlnet guidance

[dunbar12138]

https://github.com/threestudio-project/threestudio/blob/94c6ad2a4e391e8a85ac28724870bcd515b9e591/threestudio/models/guidance/controlnet_guidance.py#L347

Hi, thanks for your great work. Just have a quick question: is there a specific reason that batch_size here cannot be larger than 1?

[DSaurus]

Hi, @dunbar12138. ControlNet support both SDS and DU(dataset update proposed by instructnerf2nerf). In the DU setting, ControlNet needs to define a scheduler with a random timestep to execute multiple sampling steps for obtaining an RGB image. If the batch size is not 1, the randomly generated tilmestep may differ within the same batch, which is not permissible for a single scheduler. However, if you are only utilizing the SDS loss, I believe you can comment out this code.

[dunbar12138]

Thanks for your reply! I'll test SDS loss with larger batch_size then