LiDAR data processing are gaining importance in the field of remote sensing and geographical information system (GIS) for generating DEM ( Digital Elevation Model), TIN (Triangulated Inverse Network), DTM (Digital Terrain Model) and many other surface models. LiDAR systems or technologies are able to collect dense and accurate information from the surface or terrain. Light Distance And Ranging along with airborne laser swath mapping data is quickly becoming one of the hottest tools in the geosciences for studying earth surface. LiDAR data more accurately create DEM from any other softwares.
LiDAR data processing is divided into two steps:
- Data pre-processing: After the data acquisition it is required to process data for further analysis. In the data pre processing techniques data must be filtered for noise. The data must be corrected through the global positioning system survey. The pre processing computes the collected point coordinates from the independent parameters such as scanner position, orientation parameters, scanner angular deflection, and the laser pulse time. Most of the LiDAR file format is ASCII. ASCII file format represent x,y and z values. X,y and z values contain latitude, longitude and elevation data. For data pre-processing latitude, longitude and elevation data is required to convert into local referenced coordinate system.
- Data post-processing: After pre-processing LiDAR data is ready for post processing. To derive final products like DEM (Digital Elevation Model), DTM (Digital Terrain Model), TIN (Triangulated Irregular Network) for further analysis post processing is important. With the help of LiDAR data surface modeling can be generated. These surfaces are derived using skilled technical staff, ArcView and 3D Analyst. For generating these 3D models current aerial photography, imagery, and existing maps are required with high level accuracy. Current images or photography should be geo-referenced. If the current images are not geo referenced then collect geo-referenced 4k digital CCD imagery with a calibrated camera or lens. Post processing processes are most important and has a vast influence in the fields like 3D modeling etc.
Data delivery: Data delivery is usually represent in a ASCII file format for GIS or Geographical Information System in the correct coordinate system. Data delivery accuracy should be utilized to the greatest extent standards such as the ASPRS Large Scale Mapping Standard and the National Spatial Data Accuracy standard. The accuracy standards are important because when density of ground points are not sufficient , it should noted as low confidence.
Several technical factors have to be taken into account for the development of the LiDAR data Processing such as:
- Over 10,000 points per mile must be present in the data and for producing efficient environment large number of data points are essential.
- The management and achieving of the data.
- For generating real earth surface 3D model LiDAR data filtering is important
- Elevation points collection by using Lidar includes earth surface features like trees, buildings etc.
- Through Lidar technologies we can view the data in both 3D and 2D environment.
- The capability to generate output products that can be used within a software environment.
All types of data in Lidar system or technology are presented in ASCII file format or LAS file format. All data codes are written using C+ +, Visual basics, and the ESRI map project tool kit. With the help of LiDAR data we can also perform data management, 2D and 3D viewing etc.
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