Light Detection and Ranging, or LiDAR, operates under the same principles as radar, but uses a laser instead of radio waves. Narrow pulses of infrared light are sent from the sensor to the ground; this light is then reflected back to the sensor, which calculates the distance between the sensor and the ground based on the time it takes the light pulses to return. Our LiDAR Team actively acquires terrain data and digital color or color-infrared imagery using an aircraft-mounted Optech ALTM 3100 sensor, which can fire up to 100,000 laser pulses per second. Along with the ALTM 3100, RSI uses an integrated 3-band digital camera. The ALTM 3100 system actually records four hits from each of the laser pulses, meaning that elevation information will be gathered not only for the ground but for surface features as well. Once the data is collected, various geographic information systems (GIS) and remote sensing software packages are used to process the data. GIS software helps connect LiDAR data with information, such as linking data with parcels, land use, road names, stream names, or building names. This allows us to obtain the following information:

• High resolution true-color or color-infrared photos orthorectified to LiDAR ground models
• High resolution digital elevation models
• Detailed 3-D visualizations of watershed surface features

LiDAR can be more cost effective and more accurate for large project sites than traditional surveying methods. It is also more efficient in terms of time spent collecting data. Traditional surveying can take days or weeks, but LiDAR data capture can be completed in several hours. LiDAR also has a greater level of detail than traditional surveying, and LiDAR data and aerial photography may be collected simultaneously, which is not possible with traditional surveying methods. LiDAR data can also be used for:

• Power line corridor mapping
• Real estate development
• Property assessment
• Wetland identification and delineation
• Planning Emergency 911 routes
• Forestry applications
• Wastewater management
• Property tax assessment
• Mining permits
• Hydrologic modeling
• Stream mitigation
• Land reclamation
• Floodplain delineation