Applying the Image Matching on Intensity Data for Boresight Calibration of Airborne LiDAR
Airborne laser scanning (ALS), also known as ”airborne LiDAR”, is an active remote sensing techni... more Airborne laser scanning (ALS), also known as ”airborne LiDAR”, is an active remote sensing technique to capture surface terrain. Systematic errors in point clouds acquired by ALS may occur for many reasons. Three components of a laser system, namely, position (GPS), navigation (IMU), and range (laser scanner system), are sources of systematic errors. Firstly, each boresight misalignment parameter is discussed to assess its impact on data accuracy and methodology of recovery. The boresight calibration solution used by one of major commercial systems is introduced and the improvement on one of these approaches is proposed. The proposed automated method of extracting tie points to improve the current method on ALS system calibration can significantly upgrade the accuracy in tie point selection. Therefore, the accuracy of misalignment parameters is expected while applying a practical calibration flight.
Terrain relief is an important feature of geographic environment and a major element of topograph... more Terrain relief is an important feature of geographic environment and a major element of topographic maps. Contour lines are widely adopted as representation of terrain relief in traditional maps. In general, contour maps are still indispensable due to the following reasons: 1) Abundant terrain data are still represented by contour maps; 2) Contour maps contain fewer limits for use in different situations; 3) Reading contour maps can train students’ logical thinking. Yet, contour maps are difficult to comprehend for most students due to their abstract nature. This research takes into account three essential elements involved in contour interpretation: terrain information, map representation and spatial cognition. We incorporate these elements into the creation of terrain relief using GIS and computer mapping software, such as ArcMap and Surfer. The representation being developed include vivid ones and abstract ones so that students can learn to comprehend abstract representations of ...
On accuracy specifications of electronic distance meter
Survey Review, 2013
Abstract The electronic distance meter (EDM) is an essential surveying tool. The principle of ope... more Abstract The electronic distance meter (EDM) is an essential surveying tool. The principle of operation is the same among various EDM devices such as the stand alone EDM device, the theodolite mounted EDM unit and the coaxial design integrated with a total station. However, two interpretations exist for EDM accuracy specifications. This study investigates the meaning and cause of the two interpretations of identical accuracy specifications. Explanations from textbooks and manufacturers are reviewed. The procedures for deriving the value used in the accuracy specifications in practice are also detailed briefly. This research suggests that a unified interpretation of EDM accuracy specifications would be beneficial for EDM education and practice.
Photogrammetric Solution for Vehicle‐Damage Investigation
Journal of Transportation Engineering, 1992
When searching for an operational system for vehicle-damage investigation, photogrammetry is foun... more When searching for an operational system for vehicle-damage investigation, photogrammetry is found to provide a practical solution. A system is designed featuring low capital investment and operational cost as well as providing simple operation and requiring only a minimum of data-handling procedures. This photogrammetric system is based on the stereo-camera concept and the enlarger-digitizer procedure. It utilizes primarily inexpensive off-the shelf components for both data acquisition and evaluation. This paper describes the system, its components, and operation. The results of a number of practical cases are presented and compared to those obtained by conventional means. Language: en
Error Properties of Stadia Measurements with Incomplete Intercept
Journal of Surveying Engineering, 1995
The error properties of the stadia measurement with incomplete-intercept readings were analyzed i... more The error properties of the stadia measurement with incomplete-intercept readings were analyzed in this study. Several numerical experiments were also conducted. Finally, a comparison was made on the magnitude of the stochastic error propagated with the error introduced via the nonrigorous functional model for incomplete-intercept readings. This comparison has provided an opportunity to compare the significance of functional-error with stochastic-error components. The identified functional error can be easily removed; meanwhile, the stochastic-error component of measurement is valuable for the documentation of surveying quality.
Estimating PM 2.5 concentration with MODIS for 2013 petrochemical industrial accident
[[abstract]]The concentration of PM 2.5 (Particulate Matter) is an important indicator of air con... more [[abstract]]The concentration of PM 2.5 (Particulate Matter) is an important indicator of air condition. By 2014, there are 73 PM 2.5 monitoring stations established by the Environmental Protection Administration (EPA) in Taiwan. Based on the location and role in the further application, these stations could be classified into six types, namely, general stations, industrial stations, traffic stations, background stations, park stations and others. While the ground stations provide continuous and high precision in-situ observations, satellite borne remote sensing technique could provide a vast area coverage but with limited time epoch information. Among a number of satellite image sensors, MODIS provides a standard scientific product, MOD04, for AOD (Aerosol Optical Depth, AOD) measurement. With MOD04, PM 2.5 concentration could be estimated with correlation and regression to in-situ measurements. This study utilized the 73 EPA ground stations for an incidence occurred on Feb. 14, 2013 and Mar. 5, 2014 in the sixth naphtha cracker of Formosa Plastic Group. The result shows that the correlation index R2 between AOD and PM 2.5 is 0.50. While the AOD measurements derived from satellite images offer a way for estimating PM 2.5 concentration, further improvement in the modeling and data processing is required for reducing the uncertainty
A photogrammetric simulator for close-range applications
Photogrammetric Engineering and Remote Sensing, 1996
Simulation is an important process for project design. An algorithm specifically designed for clo... more Simulation is an important process for project design. An algorithm specifically designed for close-range applications is described in this study. This algorithm, based on human behavior, simulates the hand-held camera situation. The algorithm and a numerical example are presented. An implementation into a CAD system has been attempted, in which the initial results are rather encouraging.
Applying the Image Matching on Intensity Data for Boresight Calibration of Airborne LiDAR
Airborne laser scanning (ALS), also known as ”airborne LiDAR”, is an active remote sensing techni... more Airborne laser scanning (ALS), also known as ”airborne LiDAR”, is an active remote sensing technique to capture surface terrain. Systematic errors in point clouds acquired by ALS may occur for many reasons. Three components of a laser system, namely, position (GPS), navigation (IMU), and range (laser scanner system), are sources of systematic errors. Firstly, each boresight misalignment parameter is discussed to assess its impact on data accuracy and methodology of recovery. The boresight calibration solution used by one of major commercial systems is introduced and the improvement on one of these approaches is proposed. The proposed automated method of extracting tie points to improve the current method on ALS system calibration can significantly upgrade the accuracy in tie point selection. Therefore, the accuracy of misalignment parameters is expected while applying a practical calibration flight.
Terrain relief is an important feature of geographic environment and a major element of topograph... more Terrain relief is an important feature of geographic environment and a major element of topographic maps. Contour lines are widely adopted as representation of terrain relief in traditional maps. In general, contour maps are still indispensable due to the following reasons: 1) Abundant terrain data are still represented by contour maps; 2) Contour maps contain fewer limits for use in different situations; 3) Reading contour maps can train students’ logical thinking. Yet, contour maps are difficult to comprehend for most students due to their abstract nature. This research takes into account three essential elements involved in contour interpretation: terrain information, map representation and spatial cognition. We incorporate these elements into the creation of terrain relief using GIS and computer mapping software, such as ArcMap and Surfer. The representation being developed include vivid ones and abstract ones so that students can learn to comprehend abstract representations of ...
On accuracy specifications of electronic distance meter
Survey Review, 2013
Abstract The electronic distance meter (EDM) is an essential surveying tool. The principle of ope... more Abstract The electronic distance meter (EDM) is an essential surveying tool. The principle of operation is the same among various EDM devices such as the stand alone EDM device, the theodolite mounted EDM unit and the coaxial design integrated with a total station. However, two interpretations exist for EDM accuracy specifications. This study investigates the meaning and cause of the two interpretations of identical accuracy specifications. Explanations from textbooks and manufacturers are reviewed. The procedures for deriving the value used in the accuracy specifications in practice are also detailed briefly. This research suggests that a unified interpretation of EDM accuracy specifications would be beneficial for EDM education and practice.
Photogrammetric Solution for Vehicle‐Damage Investigation
Journal of Transportation Engineering, 1992
When searching for an operational system for vehicle-damage investigation, photogrammetry is foun... more When searching for an operational system for vehicle-damage investigation, photogrammetry is found to provide a practical solution. A system is designed featuring low capital investment and operational cost as well as providing simple operation and requiring only a minimum of data-handling procedures. This photogrammetric system is based on the stereo-camera concept and the enlarger-digitizer procedure. It utilizes primarily inexpensive off-the shelf components for both data acquisition and evaluation. This paper describes the system, its components, and operation. The results of a number of practical cases are presented and compared to those obtained by conventional means. Language: en
Error Properties of Stadia Measurements with Incomplete Intercept
Journal of Surveying Engineering, 1995
The error properties of the stadia measurement with incomplete-intercept readings were analyzed i... more The error properties of the stadia measurement with incomplete-intercept readings were analyzed in this study. Several numerical experiments were also conducted. Finally, a comparison was made on the magnitude of the stochastic error propagated with the error introduced via the nonrigorous functional model for incomplete-intercept readings. This comparison has provided an opportunity to compare the significance of functional-error with stochastic-error components. The identified functional error can be easily removed; meanwhile, the stochastic-error component of measurement is valuable for the documentation of surveying quality.
Estimating PM 2.5 concentration with MODIS for 2013 petrochemical industrial accident
[[abstract]]The concentration of PM 2.5 (Particulate Matter) is an important indicator of air con... more [[abstract]]The concentration of PM 2.5 (Particulate Matter) is an important indicator of air condition. By 2014, there are 73 PM 2.5 monitoring stations established by the Environmental Protection Administration (EPA) in Taiwan. Based on the location and role in the further application, these stations could be classified into six types, namely, general stations, industrial stations, traffic stations, background stations, park stations and others. While the ground stations provide continuous and high precision in-situ observations, satellite borne remote sensing technique could provide a vast area coverage but with limited time epoch information. Among a number of satellite image sensors, MODIS provides a standard scientific product, MOD04, for AOD (Aerosol Optical Depth, AOD) measurement. With MOD04, PM 2.5 concentration could be estimated with correlation and regression to in-situ measurements. This study utilized the 73 EPA ground stations for an incidence occurred on Feb. 14, 2013 and Mar. 5, 2014 in the sixth naphtha cracker of Formosa Plastic Group. The result shows that the correlation index R2 between AOD and PM 2.5 is 0.50. While the AOD measurements derived from satellite images offer a way for estimating PM 2.5 concentration, further improvement in the modeling and data processing is required for reducing the uncertainty
A photogrammetric simulator for close-range applications
Photogrammetric Engineering and Remote Sensing, 1996
Simulation is an important process for project design. An algorithm specifically designed for clo... more Simulation is an important process for project design. An algorithm specifically designed for close-range applications is described in this study. This algorithm, based on human behavior, simulates the hand-held camera situation. The algorithm and a numerical example are presented. An implementation into a CAD system has been attempted, in which the initial results are rather encouraging.
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Papers by Peter Shih