These models suffer the same drawbacks as above mentioned in the top-down approach for NLVL.
with the advent of the first performance comparable bottom-up object detector: CornerNet (Law and Deng, 2018), the bottom-up approaches begin to gain unprecedented attention (Zhou et al., 2019b,a;Duan et al., 2019;, which inspires us to explore a decent bottom-up framework for NLVL.