Automation in the Context of Terrestrial Surveying - Essay Example

AUTOMATION IN THE CONTEXT OF TERRESTRIAL SURVEYING AUTOMATION IN THE CONTEXT OF TERRESTRIAL SURVEYING Introduction The importance of surveying to engineering and construction cannot be underestimated. But given the fact that the outcomes of engineering and construction benefit the ordinary person in a given context, it can be said that surveying is an important academic and professional area for all people (Pugh, 1975). Surveying, and for that matter terrestrial surveying the technique and science by which professional surveyors determine the terrestrial position of points in a much accurate manner (Johnson, 2008). The determination of terrestrial points takes place by looking into the distances and angles that are between the points. Terrestrial surveying is very relevant to several engineering professions, especially those whose practice relate to the physical distance or three-dimensional position of points. In what may be referred to as a traditional way to surveying, surveyors have gone about their professional practice by measuring angles and distances. Adding other quantitative information, surveyors calculate dimensional constructs such as areas, volumes, elevations, coordinates, bearings, maps, and vectors (Genovese, 2005). Most of this form of traditional surveying has been done by the use of various 3D scanners and other aerial imagery equipment. Today, Hong-Sen & Marco (2009) observes a technological renaissance where there adoption of machine guidance systems in the performance of the same terrestrial surveying duties have increased. Such technological renaissance which is backed by the use of surveying global position systems (GPS) has created an era of automation in the context of terrestrial surveying. It is therefore not surprising that the number of GPS machine control services is increasing across the globe. Today, high definition surveying is performed by the use of 3D laser scanning. As terrestrial surveying takes what is clearly an automation approach to practice through the use of more advanced and sophisticated technological tools, it is important for research to be conducted in understanding the overall impact of automation in the context of terrestrial surveying. Such research that brings out the thorough understanding of the impact of automation in the context of terrestrial surveying is what the current research seeks to do. As the presence and use of scan laser systems in terrestrial surveying has increased the importance of surveying, the current study will look into the specific benefits that come with automation in terrestrial surveying as against what is referred to as traditional surveying. Indeed, there are many who believe that automation in terrestrial surveying does not only create opportunities but come with its own line of disruptions (Keay, 2000). With this said, the current study will also look into the possible implications for practice with automation in the terrestrial surveying. The implications for practice will focus more on training of a workforce that produces surveyors who have the most qualified experience, skill and knowledge to pursue 3D laser scanning to achieve high definition automated terrestrial surveying. The issue of cost shall also be reflected as part of the implication for practice so as to know if it is possible that the cost of engaging in automation in the context of terrestrial surveying may possibly lead to compromise in service delivery of terrestrial surveying. After these, there will be a more technical approach to automation in terrestrial surveying by focusing on high-definition surveying. This will be done by looking at the use of scan lasers and how they are used in automated terrestrial surveying. The paper will therefore end by taking a strong point on how to promote GPS machine control services as a way of enhancing automation in the context of terrestrial surveying. Background to automation in terrestrial surveying Several researchers have tried to explain and give background to what constituents an automation system in terrestrial surveying. By reviewing various works of literature, the impression that one readily gets is that automation in terrestrial surveying comes about when there is the use of modern technology in the undertaking the roles and works of terrestrial surveying (Jiang and Bunke, 2004). Once this is said, there are two major issues that come to mind, which are the use of GPS machine control services and the use of scan lasers in performing terrestrial surveying. Writing on the use of GPS machine control in terrestrial surveying, Knuth (1999) explained that this is machine guidance or automated machine control that employ the use of sophisticated technological based equipment that adds GPS functionalities to what may be a typical traditional surveying setup. These GPS machine control may not be very new when it comes to terrestrial surveying but what makes them outstanding is the fact that they seem not to have been fully utilized in the field of terrestrial surveying. The reason is this is said is that Belton (2008) observed that even though GPS machine control comes with numerous benefits, they have only been dominant in the construction industry when in reality, digital terrestrial surveying covers so many areas than just construction. Hong-Sen and Marco (2009) noted that the presence of GPS machine control allows automation in terrestrial surveying by replacing some of the old work of surveyors such as stalking, giving instructions on where and how to position blade, automatically positioning blade when needed, and calculating the amount of material that needs to be moved. Apart from the use of GPS machine control, another technique that is making automation in terrestrial surveying highly enhanced is the use of terrestrial laser scanners (TLS). Like GPS machine control, Knuth (1999) debated that TLS are not necessarily new innovations as they have been in use for over a decade now. What makes the particularly important for discussion in any modern professional and academic discourse is the fact that they have been largely underutilized in terms of what they can be used to achieve in terrestrial surveying. TLS can also be used to automate most of the traditional surveying as have already been noted above. But more to this is the fact that they are also used to undertake photogrammetric applications in terrestrial surveying. Such photogrammetric applications ensure that there is automation in roles such as data capture speed, accuracy, and density of point data obtained during terrestrial surveying (Belton, 2008). TLS have also been noted to be very dominant in road surveys, meaning that there still need to be explored further to taking full advantage of them. Below is a picture showing a 3D point cloud of a road and its surrounding structures that was taken with the use of a TLS. Figure 1: 3D point cloud Source: Lichti et al. (2005) From the discussions so far, one gets the impression that the automation in terrestrial surveying through the use of GPS machine control and scan lasers replaces the traditional staking and other roles of surveyors. Because of this, one is likely to think that by having these automation systems in place, the surveyor and the function they deliver are no longer relevant. Genovese (2005) however disagreed with this position as it was stressed that there are core limitations to automation by these modern technologies that still makes it very important to have the surveyor in place. Some of the functions of the surveyor that may not be addressed or tackled by the modern technologies include boundary resolution and topographic survey work (Genovese, 2005). Again, they are needed to offer complementary roles to the modern equipment by ensuring that the right programming is done to input the right automation of instructions. Modality of functioning Both GPS machine control and TLS seem to have similar modes by which they operate. This forms what is known as the modality of functioning or methods of operation. In the following steps, there is a display of the modality of functioning in a typical automation of terrestrial surveying as will be performed with a TLS in road construction. Finding of points on the ground In engaging a TLS in road surveying, one of the very first processes that take place is finding of points on the ground. This is because it is based on the ground points that all other decisions about angles, position and distance are taken by the surveyor. In this instance, ground points refer to the points that are considered to be the lowest, smooth, and nominally horizontal surface (Lichti et al., 2005). As part of the automation process, ground points are found by the method of defining the lowest point in the data set as the ground. It must be noted at this point that the TLS begins its processing by storing data into a 2D grid structure. This leads to the formation of cells on the ground. The definition of lowest points therefore makes it possible to identify cells that have the lowest points with a set height difference. Such cells are then labeled as containing ground points (Vosselman and Maas, 2010). In the figure below, the red points used represent the lowest ground points found in the TLS. Figure 2: Lowest ground points denoted in red Source: Kretschmer et al. (2004) Segmenting the points into regions After the most preferred points on the ground have been established, there is an extended process which segments the points into region. This is generally done to widen or broaden the scope of area that may be of use in the surveying area. Segmentation of the points into region is also done to ensure that points with similar characteristics that promote ground based decision making are brought together in a well harnessed manner (Bae, Belton and Lichti, 2007) as showed in figure 3. The segmentation is performed by first identifying every other grid cell that has a ground point. After this, a second process is used whereby all adjacent grid cells that are made up of ground points are engaged in a comparative analysis to establish if the ground points might have been sampled from the same ground surface (Bae, Belton and Lichti, 2007). Once such ground points that have been sampled from the same ground surface are found, there are either eliminated or reclassified into the most appropriate region. To ensure accuracy with outcomes, the comparison takes place by subjecting planar surface fitted to the ground point to scrutiny in each cell. Once this is done, it is possible to identify if ground points are nominally aligned (Belton, 2008). In the figure below, there is a display of the segmented ground points that has colors denoting different segments. Figure 3:Segmented ground points Source: Kretschmer et al. (2004) Finding the road Once the region has been established, the most suitable road is found. On the whole, Jiang and Bunke (2004) noted that finding the road takes place by finding the types of segments containing points sampled from the road surface. What this means is that as part of the automation of the terrestrial surveying process, there is a predetermination as to which types of points are more desirable for form the road. As a result, it is easier to identify from the segment the ones that conform to the predetermined standards. Whenever there are several segments within one single surface area, Shapiro and Stockman (2001) argued that the road is normally determined from the scene that is made up of the largest continuous and smooth surface segment. Very often, this is found in the middle of the point cloud as depicted in figure 4. In figure 4, the isolated road is painted red and represents the largest segment having one large continuous and smooth surface. In the same picture, the part pained green represents the ground points. Figure 4: Isolated road identified in red color Finding kerbs Jiang, Zhang and Ming (2005) observed that in a typical automated terrestrial surveying, the focus of the surveyor is not just about the road. Rather, surrounding features may also be deemed as very relevant to the road. With this noted, the TLS is also used to extract surrounding features that are relevant to what the contractors want to achieve. Very commonly, Fischler and Bolles (1981) noted that kerbing is one of such relevant features that are used in road construction. Because of this, the modality involves finding the right kerbs, which defines the extents of the road. As part of the automation process of the TLS, it is common to use the equipment to identify characteristics of existing kerbs. Giving the fact that by this time the cells and points might already have been found, locating kerbs becomes as simple as locating the cells that contain points similar to those sampled from the kerb. Very often, cells of this nature are found to exhibit some characteristics, which make it easier for their identification. For example, Bae, Belton and Lichti (2007) noted that such cells are located on the edge of the road segment and have the difference in point heights that is equivalent to the height of the kerb. Finding neighboring features The last process that comes under the modality of the automation of terrestrial surveying in road construction has to do with finding neighboring features that add to the advantages and use of the road as a main feature. According to Fischler and Bolles (1981), these remaining features are often identified in the form of disjointed physical structures that connect to each other only independently by the surface of the ground. These neighboring features come in different examples including poles, trees, poles and buildings. In such an instance, the automation identifies all specific structures under each of these features as one feature. That is, there may be many different buildings but they are all considered as single. Another characteristic is that there are primary features and secondary features based on the importance of the neighboring feature. Specifically, signs and light poles are captured as primary features and vegetations and buildings are regarded as secondary features (Fischler and Bolles, 1981). In the figure below, it can be noted that the road is showed in white and the other neighboring features are showed in other colors. Figure 5: Road and Neighboring Features Source: Kretschmer et al. (2004) Benefits with automation in terrestrial surveying Even though the parameters used in automation in terrestrial surveying namely GPS machine monitoring and TLS may not exactly be the same thing or function in exactly the same way, Jiang, Zhang and Ming (2005) note that the outcome that these produce tend to exhibit the same line of benefits. What this means is that once GPS machine monitoring and TLS are used to translate the activities of surveyors from manual and traditional presentation to a more automated manner, there are advantages that the automation process brings to the surveyor. One of these first benefits have been noted to be the extent to which automation in terms of terrestrial surveying helps in eliminating human errors that come about as a result of such limitations as fatigue, forgetfulness or the wrong application of procedure. This means that accuracy can be mentioned as a particular benefit that comes with the use of automation in terrestrial surveying. In terrestrial surveying, the need to have accurate outcomes cannot be underestimated. This is because of the important projects that are associated with the outcomes of surveys. For example, if a dam is to be constructed at a site and the work of the terrestrial surveyor is not able to yield accurate outcomes, this could have long term negative effects on the construction of the dam. Such long term effects could be experienced at the time of construction as well as at the time of usage of the dam. Apart from accuracy, one other benefit associated with the use of automation in terrestrial surveying is capabilities. By capabilities, reference is being made to what can be done through the use of various automation technologies. Comparing the traditional forms of surveying to automated systems, Jiang and Bunke (2004) stressed that the traditional systems were highly limited in terms of their capabilities. The reason this was so is largely because the capabilities of the surveying process was directly proportional to the capabilities of the surveyor. This is because the manual equip were manipulated and controlled by the surveyors and so much effort and work the surveyor could put into the surveying process turned out to be the over capability of the terrestrial surveying. With the automation systems however, such limitations are taken care of because the real measure of capabilities rests with the technologies and machines that are used rather than the manpower behind the process. Using the example of the TLS, Vosselman and Maas (2010) saw that this laser scan does not deal with direct contact with a feature that is of interest to the surveyor. What this means is that there is reduction in the interaction time between the surveyor and the setting where the data capture takes place such as the busy road. Using a single setup therefore, it is possible to perform very large volume of point data collection without having to worry about the limitations of the surveyor as the real mechanism behind the activity is the technological equipment and not the surveyor. What is more, efficiency through higher range of coverage has been noted to be another major benefit with the use of automation in terrestrial surveying. In terrestrial surveying, efficiency is said to be achieved when there is so much coverage or range performed or covered within a very short time frame. Efficiency therefore guarantees value for time, whereby surveyors are able to make the most out of the time available to them. With this said, Knuth (1999) explained that automated systems including GPS machine monitoring and TLS are appropriate in guaranteeing efficiency because they combine different processes and activities under surveying and renders them all at a go. This means that instead of undertaking the tasks one after the other, they are undertaken as a unit and thus much time is saved in the systematic rounds that would have been used in completing processes. Again, Shapiro and Stockman (2001) saw that automation in terrestrial surveying helps in eliminating waste and promoting lean production during the surveying process. This is because such forms of waste such as unnecessary waiting, overproduction, and production of defects are all taken care by the technological system. Unnecessary waiting is avoided because the technological systems execute several processes together and at a go. Overproduction is also avoided due to the extent of precision with which processes are executed. Also, production of defects is avoided because there is an internal evaluation system that makes it possible to detect defects and correct them before their implications are felt. Still on the benefits of the automation system in terrestrial surveying, Jiang, Zhang and Ming (2005) mentioned that the various technological equipment used in the automation processes guarantees speed durability. Even though speed is related to efficiency, the point that is being raised in this context looks very specifically at the speed of the internal processes that form part of the automated process. For example, TLS makes use of point cloud, which represent very accurate 3D data set that are scanned at the project sites. Even though traditional equipment used in terrestrial surveying can also produce these forms of 3D, the speed durability associated with them are found not to be as guaranteed as the GPS machine monitoring and TLS produces. In this context, durability is added to speed because Wu and Kobbelt (2005) observed a situation where some traditional platforms for terrestrial surveying have rendered speed with the scanning of 3D data set. However, the speed that is yielded has often been noted to compromise durability, whereby the completed works have hardly been able to withstand length of time. In the case of the automated systems however, these two features are guaranteed as part of the point cloud that is generated. With this said, it can be noted that the benefits that come with the automated systems are not those that comprise some parts of the advantages for others. Rather, all the various forms of advantages can be attained independently and separately. Challenges that limits the use of automation in terrestrial surveying Even though automation with terrestrial surveying can be seen to be very advantageous and beneficial, Wu and Kobbelt (2005) argued that it does not come to solve all the problems that there are with terrestrial surveying. This means that even with the presence of automation, there are issues that ought to be addressed if the most can be made from the GPS machine monitoring service and TLS respectively. This means that the challenges discussed here do not necessarily represent disadvantages with automation but limitations that must be addressed if the benefits discussed above can be achieved in full. One of these challenges focuses on the issue of training for surveyors. In a study by Vosselman and Maas (2010), it was noted that most institutions that are responsible for the training of surveyors admit to not having the capacity in training practitioners with the forms of advanced knowledge needed to embrace the technological renaissance that the automation systems have brought to the field of surveying. There are several factors that account for this challenge with training, including lack of modern equipment in most of these institutions. Where the equipments are available, they are not sufficient to allow independent practical use by learners. Because of this, most surveyors complete their courses without the requisite knowledge and skills to be effective with the use of automation systems of terrestrial surveying. Meanwhile, there is a core danger whereby application of these modern equipments by people who are ill-equipped can render them less beneficial. Another challenge with the use of the GPS machine monitoring service and the TLS has to do with the issue of parts and equipment. As technological based machinery, Wu and Kobbelt (2005) lamented that the issue of breakdown and wear out with parts of the equipments is very common. Meanwhile, because these automated surveying systems have not been widely embraced as the traditional forms of equipment, manufacturing of their parts is very limited. Consequently, when there are breakdown or wear out with some parts of the equipments, getting replacement becomes very difficult and challenging. This is a situation that makes most people prefer to stick with the use of traditional systems as against the use of the automated systems. There is a related problem where breakdown with just some few parts have required the need to purchase new complete equipment. This is a situation that makes most people regard the use of automation in terrestrial surveying as something that is very expensive and less cost effective. Because of this, most of these people, most of who are surveyors are discouraged from embracing the use of automation in terrestrial surveying. This is a situation that is expected to lead to lead to advocacy on the need for manufacturers in the area of surveying equipment to make machine parts commonly available. As the parts are made available, it is also very important that training will be given to surveyors on how to undertake simple maintenance processes whiles using the technological devices. It is hoped that this is a means by which surveyors will be encouraged to embrace the automation systems. Implications for practice There are several implications that the discussions that have been had so far gives for surveying practice. In the first place, the need for there to be a shift from conventional methods of surveying to automation systems can be identified. Such need can be said to have been necessitated generally because of the change in the scope of demand of projects by clients. What this means is that the projects that result from terrestrial surveys have become so complex that continuing to use the same old methods and approaches to surveying cannot be rendered effective in meeting the need of clients. A typical example of modern day project that requires advanced approach to surveying is the I-20 Bridge which is over the Chattahoochee River west of Atlanta. This is a bridge that has as many as eight lines and come with very long length. To undertake surveying for projects of this nature, one cannot employ the use of conventional methods such as total stations. In some of this cases, Shapiro and Stockman (2001) even noted that using GPS machine monitoring services may be seen as limited to achieving the total needs of surveying in such situations. With this said, it is important that there will be advancement with the approach to surveying to embrace automation that is fostered in the highest form possible such as the use of 3D laser scanning technology. This is because this form of technology comes to answer most of the difficult questions associated with terrestrial surveying. What is more, the importance of data storage in today’s computerized world cannot be neglected if any meaningful terrestrial surveying can be done. Especially at the post-processing stage of 3D point clouds, handling large volumes of unorganized point data has always become a major challenge for surveyors but this need in terrestrial surveying cannot be assumed to go away anytime soon. This gives an implication for practice whereby automated and technology based systems that samples common applications that results from billions of points after a single scanning capture is needed. Using 3D point clouds that is enabled from the TLS ensures that there are major advantages that cannot be found from general point clouds in solving this limitation for practice. For example it comes with an internalized storage and processing mechanisms that makes it possible to transfer outcomes of scans unto personal computers so that any form of post-processing activities that ought to be done can be done to the point clouds which come as raw data in this instance (Lichti et al., 2005)). With all these points, it would be admonished for practice on the need not for practitioners to compromise on success with the automation with any forms of limitation to practice that has been discussed earlier. For example, even though the overall cost of purchasing equipment and training personnel may be expensive, it is important that the long term benefits that come with automation in terrestrial surveying will rather be what will be focused on by the practitioners. Conclusion So far, it can be said that very detailed discussion has taken place on automation in the context of terrestrial surveying. Terrestrial surveying has been practiced for long and its usefulness remains as important as it is today as it was started. On the wake of industrialization, terrestrial surveying became extremely important and largely patronized because it helped in solving most the needs associated the construction that needed to take place at the time in terms of the construction of roads, factories, bridges, dams, among others. For a very long time, the approach to terrestrial surveying has not changed very much as the relatively same approach has been used in getting surveying tasks executed. Meanwhile, the fact that we are currently in a technologically controlled world cannot be denied. Such technology has made the same works that surveyors used to perform even more complex. This is because the projects that the outcomes of surveying were used to undertake such as bridges, roads and building are changing in form and type. The changes have made these projects more complex than they used to be. For example, the construction of skyscrapers has become more common, as well as the construction of glass dominated buildings. Because of these changes, the requirements and expectations are to be carried out with surveying have also changed. It can therefore be concluded that the new advocacy being made in this paper for the use of automation in terrestrial surveying is a step in the right direction. With the new modalities in place, it is very reasonable that the benefits with the automation system can be realized. References Bae K.-H., Belton D., and Lichti D.D., 2007, Pre-processing procedures for raw point clouds from terrestrial laser scanners, Journal of Spatial Science 52(2), pp. 65-74. Belton, D., 2008, Classification and Segmentation of 3D point clouds, PhD thesis, Department of Spatial Sciences, Curtin University of Technology, Perth, Australia., 183 pages Fischler, M. A. and Bolles, R. C., 1981. Random sample consensus: a paradigm for model fitting with applications to image analysis and automated cartography. Communications of the Association for Computing Machinery (ACM), 24(6), pp. 381–395. Genovese I (2005). “Definitions of Surveying and Associated Terms” London: ACSM Hong-Sen Y. & Marco C. (2009). International Symposium on History of Machines and Mechanisms: Proceedings of HMM 2008. New York: Springer Jiang, J., Zhang, Z. and Ming Y., 2005. Data segmentation for geometric feature extraction from lidar point clouds. Geoscience and Remote Sensing Symposium, 2005. IGARSS ’05. Proceedings. 2005 IEEE International 5, pp 3277–3280 Jiang, X. and Bunke, H., (2004). Fast segmentation of range images into planar regions by scan line grouping, Machine Vision and Applications, 7(2), pp. 115-122. Johnson, A. (2008). Solving Stonehenge: The New Key to an Ancient Enigma. New York: Thames & Hudson. Keay J (2000). “The Great Arc: The Dramatic Tale of How India was Mapped and Everest was Named”. New York: Harper Collins Knuth D. E., 1999, The Art of Computer Programming, Addison Wesley, 896 pages Kretschmer, U., Abmayr, T., Thies, M. and Fröhlich, C., 2004, Traffic construction analysis by use of terrestrial Laser Scanning, Proceedings of the ISPRS working group VIII/2: Laser Scanners for Forest and Landscape Assessment 36(Part 8/W2) Lichti, D.D., Franke, J., Cannell, W. and Wheeler, K. D., 2005, The potential of terrestrial laser scanners for digital ground surveys”, Journal of Spatial Science, 50 (1), pp. 75-89. Pugh J C (1975). “Surveying for Field Scientists” Texas: Methuen Shapiro L. G. and Stockman G. C, 2001, Computer Vision in Surveying, Prentice Hall, 608 pages Vosselman G. and Maas H.-G., 2010, Airborne and Terrestrial Laser Scanning, Whittles Publishing, 336 pages Wu, J. and Kobbelt, L., 2005. Structure recovery via hybrid variational surface approximation. Computer Graphics Forum 24 (3), pp277–284. Read More