Friday, February 12, 2010

Neither snow nor rain nor heat nor gloom of night...

With the recent snow storms impacting the country, I thought of no better topic than a discussion of weather and Mobile LiDAR.  It is relatively easy to work around localized weather events when utilizing a vehicle as opposed to an airplane or helicopter.  But sometimes, it's absolutely necessary to work in such conditions.

As discussed in earlier posts, LiDAR is an active sensor which uses a laser to measure distance to an object (same premise as total stations - traditional surveying instrument).  Therefore, our system can operate day or night and in virtually every weather condition.  We have several examples of night collections (Downtown Norfolk and I-85/285 in Atlanta), rain conditions (The Narrows - State College, PA) and now snow as shown below.

The image above was captured at our Beaver, PA office during snow flurries.  The image is colored by height to show all the snow in the scan (red dusting of points).  While the image below illustrates the same collection with the snow "cleaned" from the scan.  There are several different ways to accomplish this. But, it simply boils down to the intensity of the reflected light from the snow flakes and the elevation of those points.  Rain and snow each pose various processing challenges, but when you need information, sometimes it takes a little extra effort.