The Benefits of Using LIDAR Technology in GIS - Research Paper Example

 Introduction This paper presents a review of past literature on various aspects of Light Detection and Ranging (LIDAR) technology in light of its application in Geographical Information Systems (GIS). Past literature points out that LIDAR technology is more effective and appropriate in GIS as compared to other aerial photography methods such as digital camera and conventional surveying (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 528). It is in light of this that LIDAR technology is presented and illustrated with this paper with a view of describing its component technologies which makes is effective. The benefits of using LIDAR technology in GIS as a justification for the increased popularity of its use are also discussed within the paper. However, the constituent limitations that are associated with LIDAR technologies and components also determine the general accuracy of the technology. The other factors which determine the extent to which LIDAR is accurate such a flight planning and conditions are also presented within the paper. A critical analysis of LIDAR technology in comparison to the conventional or traditional methods of aerial photography is also part of the paper. LIDAR LIDAR is defined as an integration or convergence of three different but related technologies into a sole system which is capable of data acquisition and production of accurate and useful Digital Elevation Models (DEM) (Millette, Argow, Marcano, Hayward, Hopkinson and Valentine, 2010, p. 809). The three technologies which are combined into a single system in LIDAR are Global Positioning Systems (GPS), Inertial Navigation Systems (INS) and Lasers (Koukoulas and Blackburn, 2009, p. 1349). According to Greve, Kheir, Greve and Bocher (2012, p. 3), the combination of these technologies effectively leads to positioning of a laser beam footprint upon hitting an object to a very high degree of precision and accuracy. There are however limitations in the accuracy of LIDAR systems. These limitations emanate from Inertial Measurement Unit (IMU) and GPS components (Zhou, Song, Simmers and Cheng, 2008, p. 345). It is notable though that advances in technology have led to the capability of coming up with a great degree of measurement accuracy with the use of LIDAR technology within moving platforms or GIS applications such as within aircraft (Stiff, Hopkinson, Spooner and Webster, 2008, p. 42). Examples of LIDAR applications in GIS include flood risk mapping where hydrologists employ LIDAR technology to predict the possible flood extents and as a result develop effective remediation and mitigation plans and strategies for overcoming the negative implications of floods (Hamilton and Morgan, 2010, p. 134). LIDAR systems are also applied in exploration surveys for gas and oil. This is achieved through exploration programs within the gas and oil industry in which x; y and z coordinates are used to gather sensitive terrain data within exploration programs (Lewis, Fotheringham and Winstanley, 2011, p. 699). The high speed of acquiring data through LIDAR systems makes them suitable applications in oil and gas exploration. Other areas of applications that LIDAR systems are reported to be popular in include surveys in engineering and construction (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 529). For example, elevation data in construction and engineering surveys and projects is created by the use of DEMs that are developed through LIDAR (Koukoulas and Blackburn, 2009, p. 1350). The advantages of LIDAR over other aerial photography methods are also attributed for its application in real estate development, mapping pipeline corridor and transmission of power lines, mapping of costal zones and forestry (Zhou, Song, Simmers and Cheng, 2008, p. 350). Urban modelling is another area that has in the recent past employed LIDAR technology. The application of LIDAR systems in restricted access area mapping such as wetlands is also investigated and reported widely within past literature on this technology. Past researchers agree that LIDAR is one of the most enabling technologies in GIS. Greve, Kheir, Greve and Bocher (2012, p. 6) say that this is attributed to the sense that this technology has allowed the collection of data that was previously difficult to gather with the use of the traditional aerial photography methods. The forestry industry for example is said to benefit greatly from LIDAR system applications. The ease with which elevation models are acquired through LIDAR systems also makes it a suitable technology in the utility corridor arena (Millette, Argow, Marcano, Hayward, Hopkinson and Valentine, 2010, p. 810). This is as a result of the lowered cost in the development of elevation models through the GPS technology of the LIDAR systems. In this sense therefore, LIDAR systems are described to be more useful and appropriate as compared to the conventional GIS applications and methods such as photogrammetric techniques and surveys. The Benefits of Using LIDAR in GIS LIDAR systems are applicable in GIS because of their benefits as compared to other methods of aerial photography. According to Greve, Kheir, Greve and Bocher (2012, p. 8), the unique attributes and accuracies that are accorded by the application of LIDAR systems also comprise of the justification why they are considered beneficial and effective in application within GIS. For example accurate and detailed elevation measurements are achieved through the use of LIDAR in GIS. This is illustrated by studies on the classification of wetlands and the habitats that are associated with these geographical regions through the use of LIDAR. The LIDAR systems lead to a higher accuracy in such classifications as compared to the application or the use of aerial photographs only. A detailed discrimination of upland units and wetlands has been achieved and presented on NWI maps (Stiff, Hopkinson, Spooner and Webster, 2008, p. 42). The possible misclassifications of NWI units is avoided when LIDAR systems are used in GIS processes of mapping regions such as wetlands and distinguishing them from uplands (Koukoulas and Blackburn, 2009, p. 1356). Quantitative studies on the costs associated with the use of LIDAR in GIS illustrates that mapping through the LIDAR technologies such as laser is much more less costly as compared to the traditional methods of aerial photography in mapping such as digital camera (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 530). analysis of the topographic methods of collecting data during geographical mapping processes also prove the point for point low costs associated with the application of LIDAR technologies in these processes. Studies estimate that the rate of photographic data collection in the utilization of LIDAR technologies is much higher than the traditional aerial photography methods. Rates of 15 acres and up to 100 000 measurements have been recorded by researchers on the effectiveness of LIDAR technology in GIS applications. Companies which employ LIDAR have therefore cause their clients to save a lot through an efficient and effective LIDAR technological application in processes of mapping. These illustrations are in line with the fact that past literature on LIDAR technology agrees that it is much less costly as compared to other methods in GIS applications. Greve, Kheir, Greve and Bocher (2012, p. 3) point out that LIDAR systems are becoming common in GIS applications because of their GCP independence. In the use of LIDAR systems, it is only few GCPs are required in keeping the reference receiver for DGPS (Zhou, Song, Simmers and Cheng, 2008, p. 349). This means that the LIDAR systems do not necessarily need GCPs. As a result, LIDAR has been described to be the most ideal method in the processes of mapping featureless and inaccessible areas (Koukoulas and Blackburn, 2009, p. 1349). LIDAR systems also come up with additional data in GIS applications which emanates from their capacity to observe the amplitude of the back scatter form of energy (Everitt, Yang, Judd and Summy, 2010, p. 649). This results to the recording of additional data such as the reflective values that are associated with each point of data (Millette, Argow, Marcano, Hayward, Hopkinson and Valentine, 2010, p. 812). The additional data would be used for the purposes of classification of features. In addition to the lower costs associated with the LIDAR systems, it is evident that the application of these systems in GIS is based on the aforementioned benefits which makes LIDAR technology as the most preferred method of gathering topographic data and mapping processes. In accordance to Greve, Kheir, Greve and Bocher (2012, p. 10), the inherent features of LIDAR which makes it suitable for applicability within GIS include the capacity of this technology to acquire process and deliver data in the digital format. It is because of this that analysts of the technology argue that it is the easiest to work with in GIS mapping applications (Stiff, Hopkinson, Spooner and Webster, 2008, p. 42). The data products that are created or developed with LIDAR technology are suitable and applicable in meeting a wide variety of needs. It is because of this that this technology is preferred in GIS applications. The coordinate data that is developed and acquired with LIDAR technology through an illumination on the x, y and z coordinates is suitable in corresponding to three dimension positions in geographic mapping. The laser beam that is illuminated on various positions of the ground, objects and buildings is effective and accurate applications in GIS (Koukoulas and Blackburn, 2009, p. 1360). LIDAR is becoming popular in GIS because it is a revolutionizing technology in mapping and survey world (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 529). For example, hydrographic LIDAR has been improved through the incorporation of GPS and as a result provides the most appropriate tool through which data accuracy is achieved in all survey operations (White, Dietterick, Mastin and Strohman, 2010, p. 1128). The increased demand for survey services has also been met through the application of LIDAR in GIS systems. The flexibility that is offered through the use of LIDAR in GIS is argued to be one of the main reasons that is making it a popular technology in survey and mapping processes (Lewis, Fotheringham and Winstanley, 2011, p. 697). This is due to the versatile nature of the data which is gathered through LIDAR technologies. This makes the data to be useful or applicable in a wide line of applications such as detection of power lines and generation of DEM in forestry (Zhou, Song, Simmers and Cheng, 2008, p. 351). The high point density, penetrative ability and accuracy are however the most desired features of the LIDAR technology. Hamilton and Morgan (2010, p. 136) argue that as compared to other methods topographic data collection, LIDAR is the most environmental friendly method (Stiff, Hopkinson, Spooner and Webster, 2008, p. 42). Additionally, the LIDAR technology is not obstructive which makes it the preferred choice in GIS processes. Where access is limited, airborne LIDAR can be flown and used as opposed to ground survey (Millette, Argow, Marcano, Hayward, Hopkinson and Valentine, 2010, p. 815). This includes the appropriateness of LIDAR to be used in areas where it is impossible to penetrate or undesirable locations. The fact that it is not necessary for ground crew to be sent for conducting survey operations in the application of LIDAR makes it desirable for GIS operations. It is therefore the lack of ground activities such as tree cutting that makes LIDAR to be said to be the most environmental friendly approach in GIS (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 532). Limitations of LIDAR and its Accuracy It is notable that the commercially available sensors in LIDAR technology are characterized by a relatively small footprint. Past literature therefore report that this limitation is the cause of the limited resolution in the retrieval of tactical parameters in GIS especially in forestry (White, Dietterick, Mastin and Strohman, 2010, p. 1126). The commercially available LIDAR systems are also limited by the small size of diameter of its beams which causes them to miss some aspects in collection of topographic information such as the top of trees (Koukoulas and Blackburn, 2009, p. 1370). These limitations are more specifically experienced in the reconstruction of objects’ full three dimensional structures such as tree canopies in forestry (Hamilton and Morgan, 2010, p. 140). The ALS application in LIDAR also leads to a limitation of this technology. This is because ALS point wise sampling does not lead to a full area in coverage as compared to optical systems in GIS mapping (Greve, Kheir, Greve and Bocher, 2012, p. 3). This limitation leads to some errors in the processes of unterpolation depending on the kind of gridding process that is selected. Various factors affect the accuracy which is achieved in the application of LIDAR systems. These factors include the laser, Inertial Measurement Unit and GPS components (Everitt, Yang, Judd and Summy, 2010, p. 649). This is related to the fact that each of these components is characterized by limitations in accuracy. It is however important to note that in the application of LIDAR in GIS, the accuracies of these components are often predictable and understood. The other factors which determine the level of accuracy that is achieved by LIDAR technologies include flying conditions and flight planning (Jae Sung, Miller and Bethel, 2010, p. 58). Vegetation cover, terrain undulation and atmospheric effects also play a role in defining the extent to which LIDAR systems are accurate in the GIS applications (Zhou, Song, Simmers and Cheng, 2008, p. 345). In order to achieve the highest accuracies with LIDAR, quality control plans are designed and implemented. This is the role of constructors which also includes adequate ground survey checking, a process that is referred to as ground truthing. This process is necessary in validating the representative regions of the GIS project. According to Koukoulas and Blackburn (2009 p. 1370), the expected standard resolution accuracy of LIDAR technology is a 95% vertical accuracy at 36 cm. A 90% horizontal accuracy is also expected in the use of LIDAR technology at 46 cm (Lewis, Fotheringham and Winstanley, 2011, p. 702). This accuracy exceeds the FEMA guidelines in mapping (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 534). It is therefore notable that the accuracy of this technology is sufficient enough to make it appropriate and effective in GIS applications. The high resolution which characterizes LIDAR technology is related to a 95% vertical accuracy and a 90% horizontal accuracy. The final deliverable product which results in the use of LIDAR technology are expressed by a 95% tested and ascertained discreet points which fall within the recommended accuracy (Millette, Argow, Marcano, Hayward, Hopkinson and Valentine, 2010, p. 809). LIDAR versus other Aerial Photography Methods Researchers have reported comparisons between LIDAR systems and other methods of aerial photography and topographic processes of data collection. The methods that have been compared to LIDAR include inteferrometry, land surveying, photogrammetry and GPs (White, Dietterick, Mastin and Strohman, 2010, p. 1122). In general, LIDAR technologies or systems are described to be more effective than the aforementioned methods of aerial photography in GIS applications. The rate of acquisition and data processing that is achieved through the application of LIDAR systems is demonstrated to be much higher than the traditional topographic collection of data (Hamilton and Morgan, 2010, p. 138). Reports of 1000 square kilometer of acquisition and processing within 12 hours have been demonstrated by researchers in LIDAR system applications in GIS (Zhou, Song, Simmers and Cheng, 2008, p. 349). These figures are much higher when compared to the traditional methods of topographic processes of data collection (Coutu, Wyrsch, Rossi, Emery, Golay and Carneiro, 2013, p. 529). Unlike the other methods of aerial photography and topographic data collection which are entirely dependent on human control, LIDAR systems have minimal human dependence (Jae Sung, Miller and Bethel, 2010, p. 60). Most of the processes in the use of LIDAR technologies for topographic mapping and collection of data are automatic. Researchers have compared photogrammetry and LIDAR systems in relation to the level of human dependence and reported that LIDAR systems are six fold less dependent on human control and configuration as compared to photogrammetry (Stiff, Hopkinson, Spooner and Webster, 2008, p. 42). Methods of topographic data collection and aerial photography such as digital camera are dependent on the light and weather conditions (Lewis, Fotheringham and Winstanley, 2011, p. 698). On the other hand, LIDAR systems have been investigated and found to be independent on light and weather factors which are inevitably experienced in the application of GIS. Past research agree that LIDAR systems are independent on the inclination of the sun during the processes of topographic data collection and as a result making them more effective as compared to the other methods of aerial photography (White, Dietterick, Mastin and Strohman, 2010, p. 1128). A slightly bad weather and night conditions have also been reported to be less distractive of LIDAR systems (Hamilton and Morgan, 2010, p. 134). Past literature on LIDAR systems as compared to other methods of aerial photography illustrate that LIDAR technologies achieve a higher canopy penetration (Jae Sung, Miller and Bethel, 2010, p. 58). A measurement of LIDAR pulses during the processes of topographic data collection and mapping demonstrate that the LIDAR pulses have the capacity of reaching beneath any thickness of canopy (Zhou, Song, Simmers and Cheng, 2008, p. 346). It is in line with this that the measurements that are generated by LIDAR systems have been reported to be much higher that photogrammetry applications. A comparative analysis of the data density that is achieved through various methods of topographic data collection show that LIDAR systems present the highest data density of up to about 168 pulses per second (Millette, Argow, Marcano, Hayward, Hopkinson and Valentine, 2010, p. 816). Such analyses and measurements also demonstrate that LIDAR systems could measure over 24 points per meter squire (Koukoulas and Blackburn, 2009, p. 1349). The commonest attribute within past literature which describes the superiority of LIDAR systems over other methods is however the ability of these systems to come up with multiple returns in the collection of three dimensional data (Shen-En, Rice, Boyle and Hauser, 2011, p. 107). Conclusion The three technologies which are combined into a single system in LIDAR are Global Positioning Systems (GPS), Inertial Navigation Systems (INS) and Lasers (Lewis, Fotheringham and Winstanley, 2011, p. 697). LIDAR applications in GIS include flood risk mapping, surveys in engineering and construction, real estate development, mapping pipeline corridor and transmission of power lines, mapping of costal zones, forestry and urban modelling. LIDAR systems afford a high accuracy in GIS applications as compared to other methods of aerial photography. The LIDAR systems are also fast in acquisition of data and its processing which makes them preferable in GIS. The low human dependence of LIDAR systems and their ability for canopy penetrations also makes them suitable applications in GIS. The LIDAR applications are also independent of the light and weather conditions. This technology also leads to collection of useful and adequate high density data in addition to collection of additional information that is useful for classification. Past literature however attribute the low costs associated with LIDAR systems as one of the major reasons why they are preferred or used in GIS as compared to conventional methods in aerial photography. Because of the few limitations and factors which determine the level of accuracy of LIDAR systems, it is recommended that proper planning and quality control is employed in the use of these systems within GIS. 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