Enhanced Resolution on Surface Edges in 3-D Ladar Point Clouds Using Multiple Return Data
Signal processing enables the detection of more returns in a digital ladar waveform by means of computing the surface response. In prior work, it was shown that obtaining the surface response increase the range resolution from 30 cm to 14 cm for the ladar used in this work. However, this advantage presents a problem when forming a range image - each pixel contains multiple values. To overcome this issue, the location of each return inside the spatial beam footprint is estimated. This is accomplished by dividing the footprint into sections that correspond to each return and assigning the coordinates of the return to the centroid of the region. Increased resolution results on the edges of targets where multiple returns occur. Experiments focus on angled and slotted surfaces for both simulated and real data. Results show that the angle of incidence on a 75 surface is computed only using a single waveform with an error of 1.4 and that the width of the 19 cm wide by 19 cm deep slot is estimated with an error of 3.4 cm using real data. Point clouds show that the edges of the slotted surface are sharpened.