The other methods of topographic data collection are land surveying, GPS, inteferrometry, and photogrammetry. LiDAR technology has some advantages in comparison to these methods, which are being listed below:
o Higher accuracy
n Vertical accuracy 5-15 cm (1s)
n Horizontal accuracy 30-50 cm
o Fast acquisition and processing
n Acquisition of 1000 km2 in 12 hours.
n DEM generation of 1000 km2 in 24 hours.
o Minimum human dependence
n As most of the processes are automatic unlike photogrammetry, GPS or land surveying.
o Weather/Light independence
n Data collection independent of sun inclination and at night and slightly bad weather.
o Canopy penetration
n LiDAR pulses can reach beneath the canopy thus generating measurements of points there unlike photogrammetry.
o Higher data density
n Up to 167,000 pulses per second. More than 24 points per m2 can be measured.
n Multiple returns to collect data in 3D.
o GCP independence
n Only a few GCPs are needed to keep reference receiver for the purpose of DGPS. There is not need of GCPs otherwise.
n This makes LiDAR ideal for mapping inaccessible and featureless areas.
o Additional data
n LiDAR also observes the amplitude of back scatter energy thus recording a reflectance value for each data point. This data, though poor spectrally, can be used for classification, as at the wavelength used some features may be discriminated accurately.
n Is has been found by comparative studies that LiDAR data is cheaper in many applications. This is particularly considering the speed, accuracy and density of data.