This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing... more This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing of pavements and to support the development of techniques for a rapid evaluation of the conservation status of existing roads. Little research was found on this topic. The passage of a car wheel on an asphalt pavement was adopted as a case study. The DIC measurements were compared to those gathered by contact sensors. From a qualitative point of view, the DIC measurements captured the realistic shape of a deflection basin. From a quantitative point of view, the deflection values provided by the DIC system had a mean error of 0.015 mm and a standard deviation of 0.011 mm. At the moment of highest load, these errors had a mean value and standard deviation of − 0.016 mm and 0.021 mm, respectively. Thus, to improve the accuracy of the system, we propose modifying the camera support, speckle pattern, and control of natural light.
This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing... more This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing of pavements and to support the development of techniques for a rapid evaluation of the conservation status of existing roads. Little research was found on this topic. The passage of a car wheel on an asphalt pavement was adopted as a case study. The DIC measurements were compared to those gathered by contact sensors. From a qualitative point of view, the DIC measurements captured the realistic shape of a deflection basin. From a quantitative point of view, the deflection values provided by the DIC system had a mean error of 0.015 mm and a standard deviation of 0.011 mm. At the moment of highest load, these errors had a mean value and standard deviation of − 0.016 mm and 0.021 mm, respectively. Thus, to improve the accuracy of the system, we propose modifying the camera support, speckle pattern, and control of natural light.
Abstract The high level of automation, user-friendliness and cost-effectiveness of photogrammetry... more Abstract The high level of automation, user-friendliness and cost-effectiveness of photogrammetry have contributed significantly to its popularisation among amateur users in recent years. Paradoxically, this situation poses challenges when relying on the accuracy of the derived 3-D products requiring control procedures to be implemented. In this context, we present a case study of the D3Mobile project: a fully online competition for participants worldwide funded by the International Society of Photogrammetry and Remote Sensing (ISPRS). The aim is for participants to obtain reality-based 3-D models using their own mobile phones and to critically examine the metric accuracy that hides behind the beguiling realism of photogrammetry. The relative precision of the former participantś models reached values around 1:2,000, proportionally to the object size. These results provide an idea of the current level of development of photogrammetry and the potential it offers for any kind of user after proper capacity building and training.
Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inacc... more Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inaccessible for many laboratories or small factories interested in lab testing materials. These professional systems can provide reliable and rapid full-field measurements that are essential in some laboratory tests with high-strain rate events or high dynamic loading. However, in many stress-controlled experiments, such as the Brazilian tensile strength (BTS) test of compacted soils, samples are usually large and fail within a timeframe of several minutes. In those cases, alternative low-cost methods could be successfully used instead of commercial systems. This paper proposes a methodology to apply 2D-DIC techniques using consumer-grade cameras and the open-source image processing software DICe (Sandia National Lab) for monitoring the standardized BTS test. Unlike most previous studies that theoretically estimate systematic errors or use local measures from strain gauges for accuracy asses...
Infrared thermography (IRT) techniques for building inspection are currently becoming increasingl... more Infrared thermography (IRT) techniques for building inspection are currently becoming increasingly popular as non-destructive methods that provide valuable information about surface temperature (ST) and ST contrast (delta-T). With the advent of unmanned aerial vehicle (UAV)-mounted thermal cameras, IRT technology is now endowed with improved flexibility from an aerial perspective for the study of building envelopes. A case study cellar in Northwest (NW) Spain is used to assess the capability and reliability of low-altitude passive IRT in evaluating a typical semi-buried building. The study comparatively assesses the use of a pole-mounted FLIR B335 camera and a drone-mounted FLIR Vue Pro R camera for this purpose. Both tested IRT systems demonstrate good effectiveness in detecting thermal anomalies (e.g., thermal bridges, air leakages, constructive singularities, and moisture in the walls of the cellar) but pose some difficulties in performing accurate ST measurements under real oper...
Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the m... more Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the main food source for livestock. Hence, the agile, affordable, and reliable quantifcation of aboveground biomass (AGB) is an essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models were generated from data captured during two flights at different times, and the volume between them was calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomass.
Archives of Civil and Mechanical Engineering, 2022
Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inacc... more Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inaccessible for many laboratories or small factories interested in lab testing materials. These professional systems can provide reliable and rapid full-field measurements that are essential in some laboratory tests with high-strain rate events or high dynamic loading. However, in many stress-controlled experiments, such as the Brazilian tensile strength (BTS) test of compacted soils, samples are usually large and fail within a timeframe of several minutes. In those cases, alternative low-cost methods could be successfully used instead of commercial systems. This paper proposes a methodology to apply 2D-DIC techniques using consumer-grade cameras and the open-source image processing software DICe (Sandia National Lab) for monitoring the standardized BTS test. Unlike most previous studies that theoretically estimate systematic errors or use local measures from strain gauges for accuracy assessment, we propose a contrast methodology with independent full-field measures. The displacement fields obtained with the low-cost system are benchmarked with the professional stereo-DIC system Aramis-3D (GOM GmbH) in four BTS experiments using compacted soil specimens. Both approaches proved to be valid tools for obtaining full-field measurements and showing the sequence of crack initiation, propagation and termination in the BTS, constituting reliable alternatives to traditional strain gauges. Mean deviations obtained between the low-cost 2D-DIC approach and Aramis-3D in measuring in-plane components were 0.08 mm in the perpendicular direction of loading (ΔX) and 0.06 mm in the loading direction (ΔY). The proposed low-cost approach implies considerable savings compared to commercial systems.
International Journal of Applied Earth Observations and Geoinformation, 2021
Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the m... more Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the main food source for livestock. Hence, the agile, affordable, and reliable quantifcation of aboveground biomass (AGB) is an essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models were generated from data captured during two flights at different times, and the volume between them was calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomass.
The high level of automation, user-friendliness and cost-effectiveness of photogrammetry have con... more The high level of automation, user-friendliness and cost-effectiveness of photogrammetry have contributed significantly to its popularisation among amateur users in recent years. Paradoxically, this situation poses challenges when relying on the accuracy of the derived 3-D products requiring control procedures to be implemented. In this context, we present a case study of the D3Mobile project: a fully online competition for participants worldwide funded by the International Society of Photogrammetry and Remote Sensing (ISPRS). The aim is for participants to obtain reality-based 3-D models using their own mobile phones and to critically examine the metric accuracy that hides behind the beguiling realism of photogrammetry. The relative precision of the former participants’ models reached values around 1:2,000, proportionally to the object size. These results provide an idea of the current level of development of photogrammetry and the potential it offers for any kind of user after proper capacity building and training.
This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing... more This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing of pavements and to support the development of techniques for a rapid evaluation of the conservation status of existing roads. Little research was found on this topic. The passage of a car wheel on an asphalt pavement was adopted as a case study. The DIC measurements were compared to those gathered by contact sensors. From a qualitative point of view, the DIC measurements captured the realistic shape of a deflection basin. From a quantitative point of view, the deflection values provided by the DIC system had a mean error of 0.015 mm and a standard deviation of 0.011 mm. At the moment of highest load, these errors had a mean value and standard deviation of − 0.016 mm and 0.021 mm, respectively. Thus, to improve the accuracy of the system, we propose modifying the camera support, speckle pattern, and control of natural light.
This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing... more This study aims to introduce the use of 3D-digital image correlation (DIC) to the in situ testing of pavements and to support the development of techniques for a rapid evaluation of the conservation status of existing roads. Little research was found on this topic. The passage of a car wheel on an asphalt pavement was adopted as a case study. The DIC measurements were compared to those gathered by contact sensors. From a qualitative point of view, the DIC measurements captured the realistic shape of a deflection basin. From a quantitative point of view, the deflection values provided by the DIC system had a mean error of 0.015 mm and a standard deviation of 0.011 mm. At the moment of highest load, these errors had a mean value and standard deviation of − 0.016 mm and 0.021 mm, respectively. Thus, to improve the accuracy of the system, we propose modifying the camera support, speckle pattern, and control of natural light.
Abstract The high level of automation, user-friendliness and cost-effectiveness of photogrammetry... more Abstract The high level of automation, user-friendliness and cost-effectiveness of photogrammetry have contributed significantly to its popularisation among amateur users in recent years. Paradoxically, this situation poses challenges when relying on the accuracy of the derived 3-D products requiring control procedures to be implemented. In this context, we present a case study of the D3Mobile project: a fully online competition for participants worldwide funded by the International Society of Photogrammetry and Remote Sensing (ISPRS). The aim is for participants to obtain reality-based 3-D models using their own mobile phones and to critically examine the metric accuracy that hides behind the beguiling realism of photogrammetry. The relative precision of the former participantś models reached values around 1:2,000, proportionally to the object size. These results provide an idea of the current level of development of photogrammetry and the potential it offers for any kind of user after proper capacity building and training.
Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inacc... more Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inaccessible for many laboratories or small factories interested in lab testing materials. These professional systems can provide reliable and rapid full-field measurements that are essential in some laboratory tests with high-strain rate events or high dynamic loading. However, in many stress-controlled experiments, such as the Brazilian tensile strength (BTS) test of compacted soils, samples are usually large and fail within a timeframe of several minutes. In those cases, alternative low-cost methods could be successfully used instead of commercial systems. This paper proposes a methodology to apply 2D-DIC techniques using consumer-grade cameras and the open-source image processing software DICe (Sandia National Lab) for monitoring the standardized BTS test. Unlike most previous studies that theoretically estimate systematic errors or use local measures from strain gauges for accuracy asses...
Infrared thermography (IRT) techniques for building inspection are currently becoming increasingl... more Infrared thermography (IRT) techniques for building inspection are currently becoming increasingly popular as non-destructive methods that provide valuable information about surface temperature (ST) and ST contrast (delta-T). With the advent of unmanned aerial vehicle (UAV)-mounted thermal cameras, IRT technology is now endowed with improved flexibility from an aerial perspective for the study of building envelopes. A case study cellar in Northwest (NW) Spain is used to assess the capability and reliability of low-altitude passive IRT in evaluating a typical semi-buried building. The study comparatively assesses the use of a pole-mounted FLIR B335 camera and a drone-mounted FLIR Vue Pro R camera for this purpose. Both tested IRT systems demonstrate good effectiveness in detecting thermal anomalies (e.g., thermal bridges, air leakages, constructive singularities, and moisture in the walls of the cellar) but pose some difficulties in performing accurate ST measurements under real oper...
Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the m... more Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the main food source for livestock. Hence, the agile, affordable, and reliable quantifcation of aboveground biomass (AGB) is an essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models were generated from data captured during two flights at different times, and the volume between them was calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomass.
Archives of Civil and Mechanical Engineering, 2022
Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inacc... more Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inaccessible for many laboratories or small factories interested in lab testing materials. These professional systems can provide reliable and rapid full-field measurements that are essential in some laboratory tests with high-strain rate events or high dynamic loading. However, in many stress-controlled experiments, such as the Brazilian tensile strength (BTS) test of compacted soils, samples are usually large and fail within a timeframe of several minutes. In those cases, alternative low-cost methods could be successfully used instead of commercial systems. This paper proposes a methodology to apply 2D-DIC techniques using consumer-grade cameras and the open-source image processing software DICe (Sandia National Lab) for monitoring the standardized BTS test. Unlike most previous studies that theoretically estimate systematic errors or use local measures from strain gauges for accuracy assessment, we propose a contrast methodology with independent full-field measures. The displacement fields obtained with the low-cost system are benchmarked with the professional stereo-DIC system Aramis-3D (GOM GmbH) in four BTS experiments using compacted soil specimens. Both approaches proved to be valid tools for obtaining full-field measurements and showing the sequence of crack initiation, propagation and termination in the BTS, constituting reliable alternatives to traditional strain gauges. Mean deviations obtained between the low-cost 2D-DIC approach and Aramis-3D in measuring in-plane components were 0.08 mm in the perpendicular direction of loading (ΔX) and 0.06 mm in the loading direction (ΔY). The proposed low-cost approach implies considerable savings compared to commercial systems.
International Journal of Applied Earth Observations and Geoinformation, 2021
Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the m... more Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the main food source for livestock. Hence, the agile, affordable, and reliable quantifcation of aboveground biomass (AGB) is an essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models were generated from data captured during two flights at different times, and the volume between them was calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomass.
The high level of automation, user-friendliness and cost-effectiveness of photogrammetry have con... more The high level of automation, user-friendliness and cost-effectiveness of photogrammetry have contributed significantly to its popularisation among amateur users in recent years. Paradoxically, this situation poses challenges when relying on the accuracy of the derived 3-D products requiring control procedures to be implemented. In this context, we present a case study of the D3Mobile project: a fully online competition for participants worldwide funded by the International Society of Photogrammetry and Remote Sensing (ISPRS). The aim is for participants to obtain reality-based 3-D models using their own mobile phones and to critically examine the metric accuracy that hides behind the beguiling realism of photogrammetry. The relative precision of the former participants’ models reached values around 1:2,000, proportionally to the object size. These results provide an idea of the current level of development of photogrammetry and the potential it offers for any kind of user after proper capacity building and training.
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for livestock. Hence, the agile, affordable, and reliable quantifcation of aboveground biomass (AGB) is an
essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial
photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models
were generated from data captured during two flights at different times, and the volume between them was
calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing
some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of
forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and
highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomass.
for livestock. Hence, the agile, affordable, and reliable quantifcation of aboveground biomass (AGB) is an
essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial
photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models
were generated from data captured during two flights at different times, and the volume between them was
calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing
some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of
forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and
highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomass.