Recognition of bridges plays important roles in both military and civil fields.The existing researches have got some achievements

but most of them can only be applied in some limited images.What’s more

all of them are simulation algorithms based on PC

so they cannot be used in real-time applications.A real-time knowledge-based automatic recognition algorithm of bridges was introduced.This algorithm is based on FPGA and DSP

which can be widely used in aerial images or remote sensing images.It can be applied to not only close shot images

but also distant shot ones.At the same time

it can recognize several bridges in one picture.