Overview of Open Source Software for Close Range Photogrammetry

Vacca, Giuseppina

doi:10.5194/isprs-archives-xlii-4-w14-239-2019

Cited by 23 publications

(10 citation statements)

References 15 publications

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“…The methodology relies mainly on open-source (OS) software, making it more accessible in developing countries, where research funding can be scarce [18,51]. Although commercial software dominates the field, an increasing number of studies use open source software [52][53][54][55]. In terms of the processing steps required, in general, increasing the resolution of the photogrammetric analysis resulted in an increase in total processing time of 04:47:34 h from the def to the par1 and 22:14:23 h from the def to the hres settings.…”

Section: Discussionmentioning

confidence: 99%

Use of Unoccupied Aerial Systems to Characterize Woody Vegetation across Silvopastoral Systems in Ecuador

et al. 2022

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The trees in pastures are recognized for the benefits they provide to livestock, farmers, and the environment; nevertheless, their study has been restricted to small areas, making it difficult to upscale this information to national levels. For tropical developing countries, it is particularly important to understand the contribution of these systems to national carbon budgets. However, the costs associated with performing field measurements might limit the acquisition of this information. The use of unoccupied aerial systems (UAS) for ecological surveys has proved useful for collecting information at larger scales and with significantly lower costs. This study proposes a methodology that integrates field and UAS surveys to study trees on pasture areas across different terrain conditions. Our overall objective was to test the suitability of UAS surveys to the estimation of aboveground biomass (AGB), relying mainly on open-source software. The tree heights and crown diameters were measured on 0.1-hectare circular plots installed on pasture areas on livestock farms in the Amazon and Coastal regions in Ecuador. An UAS survey was performed on 1-hectare plots containing the circular plots. Field measurements were compared against canopy-height model values and biomass estimates using the two sources of information. Our results demonstrate that UAS surveys can be useful for identifying tree spatial arrangements and provide good estimates of tree height (RMSE values ranged from 0.01 to 3.53 m), crown diameter (RMSE values ranged from 0.04 to 4.47 m), and tree density (density differences ranging from 21.5 to 64.3%), which have a direct impact on biomass estimates. The differences in biomass estimates between the UAS and the field-measured values ranged from 25 to 75%, depending on site characteristics, such as slope and tree coverage. The results suggest that UASs are reliable and feasible tools with which to study tree characteristics on pastures, covering larger areas than field methods only.

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Section: Discussionmentioning

confidence: 99%

Use of Unoccupied Aerial Systems to Characterize Woody Vegetation across Silvopastoral Systems in Ecuador

et al. 2022

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“…The presented results indicated the even consumergrade non-professional solutions have the potential, especially for users without in-depth education in remote sensing data acquisition and processing, such as forest managers. Moreover, it is possible to move the processing work ow completely to an open-source solution using non-commercial SfM-MVS software (Vacca, 2019). accuracies of 76 % and 63 % in a rainforest and coniferous forest, respectively.…”

Section: Discussionmentioning

confidence: 99%

The Potential of Widespread Ready-Made UAVs in Quantifying Conifers and Delineating Their Crowns

Komárek

Klápště

Hrach

et al. 2021

Preprint

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With the ever-improving Earth observation capabilities, variables such as tree health status, biomass storage, or stand structure are increasingly estimated through remote sensing. While many protocols of data acquisition and satellite data processing are in place, the still novel unmanned aerial vehicles (UAVs) face some challenges during data acquisition and processing. While tree height extraction seems to be a common practice, identifying individual trees and measuring their crowns is still quite tricky. We performed several flights with three different UAVs and four different popular sensors over two sites with coniferous forests of various ages at flight levels of 100–200 m above ground level (AGL) using custom settings preset by UAV solution suppliers. Considering the success rate of the individual tree identification, casual RGB cameras provided more consistent results at all flight levels (84 − 77% for Phantom 4), while the success of tree identification decreases with higher flight levels and smaller crowns in the case of multispectral cameras (77 − 54% for RedEdge-M). In general, RGB cameras yielded the best results at 150 m AGL while multispectral cameras at 100 m AGL. Regarding the accuracy of the measured crown diameters, most datasets tended to overestimate when using automatic crown delineation within the lidR package. Only RGB cameras yielded satisfactory results (Mean Absolute Error – MAE of 0.79–0.99 m and 0.88–1.16 m for Phantom 4 and Zenmuse X5S, respectively). Multispectral cameras overestimated more than RGB cameras, especially in the full-grown forest (MAE = 1.26–1.77 m); on the other hand, they offered, in addition to the structural, also spectral information. We conclude that widespread ready-made solutions mounted with low-cost RGB cameras yield very satisfactory results for describing the structural forest information at 150 m AGL. When (multi)spectral information is needed, we recommend reducing the flight level to 100 m AGL to acquire sufficient structural forest information.

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“…Therefore, the more feature points are found in each image and the more these feature points correspond across images, the better the result. For this step, the SfM approach was utilized using the VisualSFM GUI application Open Source by Changchang Wu [ 22 ]. This consists of a set of techniques that calculate a 3D point cloud based on a compilation of 2D images collected around the object to be inspected.…”

Section: Methodsmentioning

confidence: 99%

An Anatomical Thermal 3D Model in Preclinical Research: Combining CT and Thermal Images

Schollemann

Pereira

Rosenhain

et al. 2021

Sensors

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Even though animal trials are a controversial topic, they provide knowledge about diseases and the course of infections in a medical context. To refine the detection of abnormalities that can cause pain and stress to the animal as early as possible, new processes must be developed. Due to its noninvasive nature, thermal imaging is increasingly used for severity assessment in animal-based research. Within a multimodal approach, thermal images combined with anatomical information could be used to simulate the inner temperature profile, thereby allowing the detection of deep-seated infections. This paper presents the generation of anatomical thermal 3D models, forming the underlying multimodal model in this simulation. These models combine anatomical 3D information based on computed tomography (CT) data with a registered thermal shell measured with infrared thermography. The process of generating these models consists of data acquisition (both thermal images and CT), camera calibration, image processing methods, and structure from motion (SfM), among others. Anatomical thermal 3D models were successfully generated using three anesthetized mice. Due to the image processing improvement, the process was also realized for areas with few features, which increases the transferability of the process. The result of this multimodal registration in 3D space can be viewed and analyzed within a visualization tool. Individual CT slices can be analyzed axially, sagittally, and coronally with the corresponding superficial skin temperature distribution. This is an important and successfully implemented milestone on the way to simulating the internal temperature profile. Using this temperature profile, deep-seated infections and inflammation can be detected in order to reduce animal suffering.

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Overview of Open Source Software for Close Range Photogrammetry

Cited by 23 publications

References 15 publications

Use of Unoccupied Aerial Systems to Characterize Woody Vegetation across Silvopastoral Systems in Ecuador

Use of Unoccupied Aerial Systems to Characterize Woody Vegetation across Silvopastoral Systems in Ecuador

The Potential of Widespread Ready-Made UAVs in Quantifying Conifers and Delineating Their Crowns

An Anatomical Thermal 3D Model in Preclinical Research: Combining CT and Thermal Images

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