Centerpoint exported scn.onnx which has input of 1*5, is it reasonable?

Description

for program CUDA-centerpoint in github, exported scn.onnx has
the input of 15(node 0 in illusttrative piture of bulletin), from common sense, the input should be N5, not 1*5, what the point inside this program?

Environment

TensorRT Version:
GPU Type: RTX3060
Nvidia Driver Version: 535
CUDA Version: 11.8
CUDNN Version: 8.6
Operating System + Version: Ubuntu20.04
Python Version (if applicable): 3.10
TensorFlow Version (if applicable):
PyTorch Version (if applicable): 2.2.2
Baremetal or Container (if container which image + tag):

Relevant Files

see here