CONSTRUCTION LiDAR APPLICATIONS
DUE DILIGENCE STUDIES
In the context of land acquisition and land development, information systems are gathered through due diligence studies. These studies are conducted for the wider performance of an investigation with proper bathymetric and as-built surveys.
LiDAR survey, the relatively new technique in baseline mapping, takes only a few days on data gathering and validation, achieves a millimeter-level of accuracy and delivers a very detailed scan of structures and features—all which explains why LiDAR survey is the better solution than conventional or ground surveys for construction surveying.
Topographic construction surveying is conducted to determine the configuration of the Earth's surface, defined by the elevation of points on a portion of land and the location of natural and man-made features on it. Topographic maps are presented as contour lines showing the elevation data and symbols representing structures and features on a plot.
For forest areas or highly vegetated lands, the capability of the LiDAR equipment to penetrate vegetation makes it possible to acquire detailed ground or topographic points through aerial survey. The contour map is further enhanced by overlaying the Orthophoto image, captured simultaneously during the airborne 3D laser scanning. LiDAR point clouds can further be represented as 3D Digital Models, Virtual Reality Environment and Data Simulations, through utilization of GIS Softwares.
Three Dimensional (3D) detailed as-built laser scanning, which also makes use of the LiDAR technology, is highly applicable to industrial, structural, architectural, civil works, and construction survey. It makes use of a stand-alone static high-speed 3D scanner, which has a ranging error of only ±2mm and scan objects up to 330 meters away, even in direct sunlight. With this capability, large buildings, industrial facilities, bridges, and vast terrains can be surveyed quickly, precisely, and reliably. Precision and accuracy increases the confidence level and reduces efforts involved in post processing methods, such as distance measurements, area and volume calculations, analysis and inspection tasks and documentation. A virtual reality environment of the scanned object is also produced by rendering the corresponding color of the scanned points from captured orthophotos.
ROAD DESIGN AND PROFILE
Designing road alignments is highly dependent on the topo-configuration of the terrain. Obtaining a very detailed topographic map is essential in a construction survey in order to establish a road profile that matches with specific route considerations and allowable cut-and-fill deviation. The capability of LiDAR systems to produce very detailed and accurate topo- and as-built maps is ideal for critical road designs and route surveys.
For existing road networks, actual condition of roads such as surface potholes and emerging cracks can be detected using LiDAR application for mobile 3D laser scanning. This method may also be used to survey the immediate areas along a predefined for mobile 3D laser scanning. This technology is a convenient alternative for road, vicinity, and project inspections.
ONGOING ASSESSMENT AND POST CONSTRUCTION
Quality assessment of on-going and newly constructed projects can now be done quickly and reliably through airborne laser scanning, mobile/terrestrial laser scanning, or detailed as-built survey, whichever is the appropriate LiDAR survey method to specific project concerns. Engineering plans and 3D Models are generated accurately using these methods, and serve as the basis for tracking progress, condition and quality, such as column and beam deflections, floor elevation and slope, high-rise alignment, dimensions, and design conformity.
When erecting buildings, figuring out elevation models, or simply studying the topography of an urban municipality, a construction survey should be in the top of the list.