Common LiDAR Survey Errors
Causes of Errors include positional erros with the GPS/IMU, range, scan angle, boresight angles, lever-arm offsets. These are systematic errors and corrections can be applied over the entire dataset. Range Errors – Not corrected for, occur due to recording of the time between emission and return of laser – centimeter scale. Beam Divergence – Common […]
RADAR – Geometric Distortions
Geometric distortions of radar include foreshortening, layover and shadowing. Foreshortening and layover distortions are related to terrain. These errors are unlikely to occur in flat terrain. In rugged terrain higher elevation is detected by the sensor first which makes it seem closer than it actually is. Any terrain feature with a slope inclined toward the […]
RADAR – Active Microwave
RADAR Sensors have a transmitter which send a pulse of electromagnetic radiation through the antenna at a specific wavelength and duration. These are off-nadir imaging sensors meaning that the have a look direction and angle which is controllable. The microwaves transmitted by the RADAR Sensors are much longer than visible, infrared or thermal infrared energy […]
Active vs Passive Sensors
This is sort of where it all begins. Remote sensing systems can be classified into 2 types : Active and Passive. Passive sensors collect information without emitting any kind of signal. What this means is that it uses the electromagnetic energy that the sun emits and records the reflectance off of the earth. This includes […]
What is LiDAR?
LiDAR is a method of remote sensing that uses laser pulses to gather information about the surface of the earth. Each laser has multiple returns to the sensor which are displayed as a cloud of points. LiDAR data is often collected from a fixed wing plane or helicopter. The height the survey is flown at […]
Landsat Imagery Viewer
Libra is a web interface that lets you scroll through landsat imagery based on year and cloud cover. Take a look! http://libra.developmentseed.org/