An Example of Range Data

Figure 1 shows a typical dataset of reflectance and range data, resampled onto a grid). The projection is spherical (each column is a longitude where the samples are spaced at equal angles), as it most naturally matches the rangefinder's rotating mirror and panning unit.

  

Figure 1: The spherical image of reflected laser light and range data. Each column starts at 60 degrees below the horizon going up, over the North Pole (middle of the image) continuing down the other side, until 60 degrees below the horizon is again reached for a total of 300 degrees per column. The horizontal field-of-view is 180 degrees, providing a full panorama of the environment that is only missing a 60 degrees cone towards the floor.

  

Figure 2: A reprojection looking toward the windows using the data from figure 1. The scenery outside the windows is too far away to reflect enough light and is shown as black.

  

Figure 3: A view from above a computer table. A chair, keyboard and monitor are on the left. Next to the table, on the right, is a computer with all of its wires shown behind it.

  

Figure 4: A view showing the ceiling tile pushed upward, allowing us to calibrate the azimuth.

The data is shown in subsequent figures (2, 4, and 3) visualized as point-clouds, using the reflected intensity of the laser light to color each point. The images are captured from a visualization tool as we move through the data. We use this tool to explore the data, modifying it with a variety of techniques (described later in the paper) to eliminate errors in the data. Figures 2 and 3 are rendered from a single set of range data collected in figure 1. Figure 4 is from an earlier set acquired in the same room during a calibration experiment (described fully in section VI-A).