| Range Data | Reflected Laser Light |
|---|---|
| 
|
| Range data, where black is close, white is far. | Reflected light data, which is how the world looks in the IR domain. |
| These images have been histogram equalized to improve the visual quality. If you'd like the original data, please let me know. | |
Above is a scan using the pan-tilt unit in conjunction with the laser rangefinder. The scanner is about 1 meter off the floor (notice the height of the desktop), hopefully soon it will move to eye-level. The FOV in both directions is 120 degrees. The scan took a little while, so I stood in its path over near the door, eyes shut, hoping the wires wouldn't get caught on anything.
With the laser mounted on the panning unit, it is not as steady as one would hope. To compensate, I overcompensated during the scan, taking 4 scans for each column of data, averaging the results. This adds considerably to the scanning time, unfortunately, and I still didn't get good range info on the light difusers.
| Range Data | Reflected Laser Light |
|---|---|
| 
|
| Range data, where black is close, white is far. The green pixels have no useful depth information (there was not enough light reflected). | Reflected IR light data. |
Above is a scan using my office chair as the rotating platform. I was curious about "going over the pole" where each scan is a longitude, and the data collected goes from -30 degrees below horizontal to 120 degrees (straight up plus another 30 degrees) along each longitude. As before, I rotated the chair slowly and steadily by hand during the scanning period (several minutes). The range is reported in inches, as before (see below). The hFOV is the better part of 180 degrees.
[I've notice that these gray-scale images look ALOT better on some monitors than others!]
| Range Data | Reflected Laser Light | Ambient Light |
|---|---|---|
| 
| 
|
Above is a scan using my office chair as the rotating platform. I rotated the chair slowly and steadily by hand during the scanning period (about 1 minute). The vertical field of view (vFOV) spans from -45 degrees to 60 degrees (as I recall), a very wide-angle. The view is from the window towards the door. The range is reported in inches, shown as gray values, thus everything in this image is closer than 256 inches (21'4"). The image is a spherical projection.
Things to note: The legs on the chair in the image and the table post are shiny and black, thus no data was returned. The dark black stripes on the bookshelf are shiny, black books (from siggraph, no doubt), again, no data returned. The light fixtures are noisy from the chrome grills. The white blocks near the center (of the range image) are returns going through my office door window, hitting the opposite wall (map of the World). Also note the curving distortion of the light fixtures on the ceiling.
The reflected light image is a measure of the strength of the returning laser light. I have "equalized" this image to provide higher contrast. The original image is smoother-looking, though much flatter. I'm impressed that even the wood grain on the bookshelf is accurately read.
The ambient light is a measure of the light coming into the sensor that is not modulating as the laser is. It is very dim (only 13 levels, all down near 0), since I have a dark ruby red filter on the rangefinder specifically designed to eliminate as much ambient light as possible (more accurate range readings).
The image is 320x240, black is near, white is far.
What next?
Mount it on the panning unit, fix up the software a bit, and move into the HMD lab!
