Architecture of the encoder of OPUS-DSD. This diagram shows the encoder that translates a 2D cryo-EM image into the latent encoding. The top row denotes the dimensions of the intermediate tensors. The arrow links the input and output of the operation above. FC, fully connected layer; Conv3D, 3D convolution; ST, spatial transformer (which back-projects the 2D image to a 3D volume). The number of channels of the convolution kernel can be derived from the dimensions of its input and output. The ellipsis represents the repeating of the preceding operation until the tensor reaches the output dimension. All convolutions and fully connected layers except the last one had LeakyReLU 33 (leaky rectified linear unit) non-linearity with a negative slope of 0.2.
