Dissertations / Theses on the topic 'Aerial photography in forestry. Aerial photogrammetry'

Thesis (M.S.)--Northwest Missouri State University, 2006.
The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on January 25, 2008) Includes bibliographical references.

To date aerial photography and associated photogrammetric and photo-interpretation techniques have played but a limited role in the planning process. In this study their dual role (i) as a base medium and (ii) as a source of data is investigated bearing in mind the requirements of planning data and certain inherent defects of conventional maps in the planning process. Having considered certain pertinent technical aspects of aerial photography and associated techniques, especially modern developments such as orthophotos, use of multi-emulsion photography, automated data extraction and automated data processing techniques, the application of these techniques is discussed in greater detail in respect of the dual role mentioned earlier. Aerial photographs are shown to be of considerable value to the planner as an analytic tool and a powerful source of data when dealing with such topics as feasibility studies, land use, resource surveys, urban and regional research and analysis, urban history, urban and rural administration, site evaluation, transportation and other. branches of engineering, urban sociology and economics, as well as urban aesthetics. Aerial photographic data adequately meets the data requirements of the planning process and furthermore lends itself to modern automatic data processing methods. The modern improved forms of photography, i.e. photomaps, orthophotos, etc. have definite advantages over conventional maps insofar as a base medium in planning is concerned, and the wider use of aerial photographs and products is anticipated when planners become more aware of their universal application and versatility.

Bayesian estimates of gross cubic- foot volume per acre were computed for four stand types (plantation pine, natural pine. hardwood. and mixed wood stands) using aerial photo volume tables as the prior information source. Aerial photographs provided a reliable source of information even though most photographs were nearly five years old. For a given level of precision within a particular stand, Bayesian methods reduced the required field sample size up to 50% using all or half of the prior information available. Those priors which utilized a regression or a regression/topographic correction in the estimation of photo heights required less field information for the given precision level than those priors which used uncorrected or topographic corrected photo heights. In order to obtain meaningful gains in sample size reduction corrections to the estimated photo heights should be made. Although the uncorrected prior produced generally less biased estimates. the reduction in sample size was not as large as that observed using other prior types. Greater gains were attributed to the better accuracy of the prior distribution. Although Bayesian methods are biased, it appeared that these methods tempered severely biased prior distributions. In the hardwood stand for example, the average bias present in the photo volume data amounted to -140%. After combining the prior with the field sample, the greatest average bias was -50%. Bayesian methods performed better than the traditional estimation methods in terms of precision. In a one to one comparison. the Bayes standard error was consistently less than its non-Bayes counterpart. The one exception to this trend was the regression prior from the hardwood stand. The poor performance of the prior was due to the weak height regression correction equation. Modal priors utilized were not subject to the extreme input values for prior distribution development as their conservative empirical prior counterparts were. Less overall variation was observed 1n the estimated values. Under the conditions for mode selection set forth in this project, modal priors provided another good source of prior information.
Master of Science

Thesis (M.S.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains x, 128 p. : ill. (some col.), maps (some col.) Vita. Includes abstract. Includes bibliographical references (p. 116-121).

From the known image positional errors on aerial photographs, this thesis computes and evaluates acreage estimation errors. Four hypothetical tracts were used in simulating aerial photographs with 104 different camera orientation combinations. Flying heights of 4000 and 6000 feet, focal lengths of 24 and 50 millimeters with and without lens distortion, and tilts of 0, 3, 6, and 12 degrees were simulated. The 416 photographs were all simulated with the camera exposure station centered above the midpoint of the respective tract's bounding rectangle. The topographic relief of the tracts ranged from 19 feet in the Coastal Plain to 105 feet in the Piedmont.

It was found that lens focal length did not have an independent effect on the acreage estimates. Relief error, the lowest, averaged -0.080%. In comparison, small errors in calculating scale were shown to be larger than relief errors. Tilt was recommended to be limited to six degrees, averaging +1.6% error at six degrees tilt. Because of its positive exponential nature when the tracts are centered, tilt can induce large biases. including tilts from zero to six degrees,the average was 0.634%. Lens distortion error averaged -0.686%. Overall, the average acreage error was 0.363% for simulations up to and including six degrees of tilt with and without lens distortion. This result is for centered tracts, and it was felt many of the errors were compensating given this situation. In conclusion, the photographic images can estimate areas to $1%, however, additional errors are imparted during actual measurement of the photographs.
Master of Science

The potential for using large scale, small format aerial photography to obtain seedling density and woody competition information was investigated. Factors affecting photo interpretation of seedlings were examined and equations to predict seedling density and woody competition levels were developed and evaluated. Two scales of imagery, 1:4000 and 1:6000 were considered to compare their relative merits for these purposes. Greater age of the seedlings and their inherent development generally served to improve photo interpretation. The amount of woody competition present in the plots tended to hinder seedling identification at the 1:4000 scale, while enhancing it when 1:6000 scale data was used. Seedling density estimation and evaluation of competition through Free-To-Grow classification predictions yielded results comparable to ground surveys. Estimation of total groundline basal area in all woody competition, and classification of the plots by the amount of hard-to-control competition they contained, were less successful. These results may have been due in part to the partial leaf fall that occurred prior to obtaining the imagery. Many of the results found in this study favored the larger scale (1:4000) imagery, and its use for the procedures described is recommended.
M.S.

Une gestion raisonnée et multifonctionnelle des forêts n'est possible qu'avec une description à jour de l'état de la ressource naturelle.Les inventaires forestiers traditionnels, réalisés sur le terrain, sont couteux et ne couvrent qu'un échantillonnage de la surface boisée.L'essor des drones civils pour la cartographie a initié une révolution dans le domaine de la télédétection environnementale.La polyvalence et la diversité des systèmes drones sont une aubaine pour la foresterie de précision.Ceux-ci sont utilisé pour la réalisation de cartographie très fine des habitats naturels avec une résolution temporelle et spatiale sans précédent.Nous explorons les possibilités d’utilisation de mini-drones pour la caractérisation quantitative et qualitative de la ressource forestière.Nous nous intéressons en particulier à l’estimation de la hauteur des arbres et à la caractérisation de la composition spécifique au sein de peuplements forestiers.La hauteur de la canopée est une variable dendrométrique de première importance : elle est un bon indicateur du stade de développement des peuplements et intervient notamment dans les estimations de biomasse ou de niveau de productivité.La composition spécifique est une information essentielle en regard des principales fonctions que remplit la forêt (conservation, production, récréation, etc).Nous avons comparé l'estimation de la hauteur des peuplements à partir de mesures LiDAR et celles obtenues par photogrammétrie.Bien que permettant une mesure de hauteur individuelle avec une incertitude de l'ordre de 1.04 m (RMSE) en feuillus, la photogrammétrie par drone sur des zones forestières est systématiquement moins précise que les mesures par LiDAR (RMSE de 0.83 m).Néanmoins, la grande flexibilité que confère les petits drones permet d'acquérir, au moment propice du stade de végétation, et l'information de relief de la canopée, et l'information spectrale.La période de fin de feuillaison, au début du mois de juin, s'est avéré le moment le plus propice à une discrimination automatique de cinq groupes d'essences feuillues (le chênes pédonculé, les bouleaux, l'érable sycomore, le frêne commun et les peupliers).Une erreur globale de classification des houppiers de 16% est obtenue avec des acquisitions monotemporelles, alors que l'utilisation d'imageries acquises à différentes dates permet encore d'améliorer cette classification.Les contraintes de la législation régissant l'utilisation des aéronefs sans pilote à bord restreignent le champs d'action des drones civils.Ainsi, les opérations avec un drone sont limitées sous un seuil d'altitude et à une distance maximale du télépilote, ce qui ne permet pas une utilisation optimale de cette technologie pour la couverture de grands domaines forestiers (plusieurs milliers d'hectares).C'est pourquoi nous pensons que les drones resterons un outils d'analyse de petites surfaces (dizaines voire centaines d'hectares), plus utiles à des fins de recherches scientifiques qu'à une utilisation en gestion forestière
The recent development of operational small unmanned aerial systems (UASs) opens the door for their extensive use in forest mapping, as both the spatial and temporal resolution of UAS imagery better suit local-scale investigation than traditional remote sensing tools.Along with this rising use of drones, dense three-dimensional reconstruction through the combined use of photogrammetry and textit{Structure from Motion} techniques enables now the fine modelization of the canopy surface relief from a set of overlapping images.Forest management is evolving and has to cope with numerous news demands.A sustainable managemnent practice requires beforehand up-to-date and comprehenvise forest inventory.Traditionnal forest ressources inventories are carried out on the field.They are expensive and focus only on an sample of the forest.Information is delivered at the stand level, and specific measurements for individual tree is missing.The use of mapping drones can potentially changes the story by describing forest ecosystems on a tree-level.This thesis aims at investigating the use of unmanned aerial systems for the characterization of temperate forests (in Wallonia, Belgium).Modelization of the vegetation heigth also is investigated by the combinaison of photogrammetric canopy surface measurements with digital terrain elevation acquired by LiDAR.Eventually, the study of a time series of 20 drone fligths through the growing season enables to determine when is the optimal period for automatic classification of deciduous species.Photogrammetric measurements of individual deciduous tree heigth are always less accurate than high density LiDAR measurements (RMSE of 1.04 m versus 0.83 m for the latter).Nevertheless, the versatility of drones is far higher than LiDAR data, with the possibility of flying at the appropriate time and delivering both spectral and 3D information with a very high resolution.Spetral information is relevant among other for tree species identification.The optimal phenology state for the discrimination of deciduous species was demonstrated to be the end of leaf flush.The intra-species phenology is indeed well synchronized during this time windows ranging from late spring to early summer.A global classification error of 16% is reached by using single date UAS imagery, and multitemporal UAS acquisitions still improve the process of species discrimination.Altough precision forestry can largely benefits from UAS technology, legislation constraints limit the operationnal use of drones.Thus, UAS flights are most of the time restricted under a specific altitude and within a certain distance from the remote pilot.These constraints are sub-optimal for the mapping of forest, which requires beyond line of sigth fligth at relatively high altitude.We thus believe that the drone technology will be more developped for scientific investigations at a local scale (dozens or hundreds of hectares) than for forest inventory of large forest estate (thousands of hectares)

Thesis (Ph.D.) - University of Glasgow, 2009.
Ph.D. thesis submitted to the Faculty of Physical Sciences, Department of Geographical and Earth Sciences and the Faculty of Arts, Department of Archaeology, University of Glasgow, 2009. Includes bibliographical references. Print version also available.

Three-dimensional canopy relectance models provide a physical-structural basis to satellite image analysis, representing a potentially more robust, objective and accurate approach for obtaining forest cover type and structural information with minimal ground truth data. The Geometric Optical Mutual Shadowing (GOMS) canopy relectance model was run in multiple-forward-mode (MFM) using digital multispectral IKONOS satellite imagery to estimate tree height and stand volume over 100m2 homogeneous forest plots in mountainous terrain, Kananaskis, Alberta. Height was computed within 2.7m for trembling aspen and 1.8m fr lodgepole pine, with basal area estimated within 0.05m2. Stand volume, estimated as the product of mean tree height and basal area, had an absolute mean difference from field measurements of 0.85m3/100m2 and 0.61m3/100m2 for aspen and pine, respectively.
xiii, 143 leaves : ill. (some col.) ; 29 cm.

The multiple-forward-mode (MFM) inversion procedure is a set of methods for indirect canopy relectance model inversion using look-up tables (LUT). This thesis refines the MFM technique with regard to: 1) model parameterization for the MFM canopy reflectance model executions and 2) methods for limiting or describing multiple solutions. Forest stand structure estimates from the inversion were evaluated using 40 field validation sites in the Canadian Rocky Mountains. Estimates of horizontal and vertical crown radius were within 0.5m and 0.9m RMSE for both conifer and deciduous species. Density estimates were within 590 stems/ha RMSE for conifer and 310 stems/ha RMSE for deciduous. The most effective inversion method used a variable spectral domain with constrained, fine increment LUTs. A biomass estimation method was also developed using empirical relationships with crown area. Biomass density estimates using the MFM method were similar to estimates produced using other multispectral analysis methods (RMSE=50t/ha).
xvi, 156 leaves : ill. (some col.), maps ; 29 cm.

Leaf area index (LAI) provides forestry information that is important for regional scale ecological models and in studies of global change. This research examines the effects of mountainous terrain on the radiometric properties of multispectral CASI imagery in estimating ground-based optical measurements of LAI, obtained using the TRAC and LAI- 2000 systems. Field and image data were acquired summer 1998 in Kananaskis, Alberta, Canada. To account for the influence of terrain a new modified approach using the Li and Strahler Geometric Optical Mutual Shadowing (GOMS) model in 'multiple forward mode' (MFM) was developed. This new methodology was evaluated against four traditional radiometric corrections used in comination with spectral mixture analysis (SMA) and NDVI. The MFM approach provided the best overall predictions of LAI measured with ground-based optical instruments, followed by terrain normalized SMA, SMA without terrain normalization and NDVI.
xiv, 151 leaves : ill. (some col.), map ; 29 cm.

Nesta dissertação é apresentado o desenvolvimento de uma ferramenta computacional para o processamento de pares de imagens estereoscópicas obtidos por câmeras aéreas métricas e não métricas. O programa foi desenvolvido na linguagem C++ e foi utilizado a biblioteca OpenGL. O resultado obtido é uma imagem tridimensional de onde pode ser extraídas cotas de altura e formas de terreno. Estas imagens poderão ser usadas no estudo de áreas de risco em encostas.
In this dissertation is presented the development of a computational tool for the processing of pairs of images estereoscópicas obtained by metric and not metric aerial cameras. The program was developed in the program language C++ and the library was used OpenGL. The result of the program is a three-dimensional image from where it can be extracted height quotas and land forms. These images can be used in the study of risk areas on slopes.

Forest canopies are a critical component of forest ecosystems as they influence many important functions. Specifically, the structure of forest canopies is a driver of the magnitude and rate of these functions. Therefore, being able to accurately measure canopy structure is crucial to ensure ecological models and forest management plans are as robust and efficient as possible. However, canopies are complex and dynamic entities and thus their structure can be challenging to accurately measure. Here we study the feasibility of using lidar to measure forest canopy structure across large spatial extents by investigating the compatibility of aerial and terrestrial lidar systems. Building on known structure-function relationships measured with terrestrial lidar, we establish grounds for scaling these relationships to the aerial scale. This would enable accurate measures of canopy structural complexity to be acquired at landscape and regional scales without the time and labor requirements of terrestrial data collection. Our results illustrate the potential for measures of canopy height, vegetation area, horizontal cover, and canopy roughness to be upscaled. Furthermore, we highlight the benefit of utilizing multivariate measures of canopy structure, and the capacity of lidar to identify forest structural types. Moving forward, lidar is a tool to be utilized in tandem with other technologies to best understand the spatial and temporal dynamics of forests and the influence of physical ecosystem structure.

Historically the U.S. Forest Service has used uncorrected aerial photographs to delineate proposed and past management activities on the land base it manages. Transferring a boundary from an image not planimetrically correct to a planimetrically corrected image introduces errors. Positional accuracy of boundaries affects the number of acres the Forest is accountable for managing, and the annual sale quantity (ASQ) or annual board feet targets. The purpose of this study was to develop a methodology that eliminated the need to transfer the boundary from an uncorrected to a corrected image. Raster and vector warping methods were evaluated with reference to positional accuracy and efficiency. Due to the rugged topography of the Siuslaw National Forest, selection of ground control points (GCPs) was an important function in the accurate transformation of images. A Vector warping method, Rubber Sheeting the ARC/INFO projective transformation for all digital GCPs, to all of the Global Position System (GPS) ground control points, provided the most accurate rectification of vector boundaries that had been digitized or scanned from an uncontrolled low elevation photograph.
Graduation date: 1992

Dissertação de mestrado em Geociências (área de especialização em Dinâmica Externa e Mudanças Globais)
A zona costeira é um espaço físico com características únicas e especiais que a tornam diferente das restantes, com um dinamismo próprio condicionado pela intervenção de fenómenos naturais e antrópicos. Com os municípios do litoral tendem a atrair e fixar mais população, resultando no aumento da densidade populacional, um programa de monitorização eficaz torna-se assim ainda mais importante. A gestão destes setores litorais requer um profundo conhecimento das características iniciais do sistema para que seja possível prever o seu comportamento futuro e de modo a determinar os fatores que influenciam a dinâmica presente no litoral. Para este trabalho, selecionaram-se como áreas de estudo as praias de Belinho, de Cepães e do Fieiro Alto, pertencentes ao concelho de Esposende, com o objetivo de testar algumas técnicas de monitorização baseadas em veículos aéreos não tripulados. Este trabalho utilizou como base a fotografia aérea recolhida através de VANT, para aplicação de técnicas de fotogrametria e modelação 3D recorrendo ao software AgiSoft PhotoScanPro, levantamentos com um sistema móvel de GPS diferencial para ortorretificar os ortomosaicos e os modelos digitais de superfície (MDS) obtidos, e por fim tecnologias de Sistemas de Informação Geográfica para: - efetuar a medição de volumes de modo a obter balanços sedimentares através dos modelos 3D; - avaliar tendências evolutivas da morfodinâmica do sistema costeira; - criar uma base de dados, o mais completa possível, para futuros estudos e campanhas de monitorização; - demonstrar a eficácia e aplicabilidade dos modelos 3D, gerados através deste método de recolha de informação, para trabalhos neste setor. Os resultados obtidos permitem concluir que este método é bastante eficiente e fiável, sendo possível obter uma grande gama de informação bastante pormenorizada e de baixo custo. Todas as informações obtidas são ferramentas extremamente úteis e valiosas no que toca a gestão dos setores costeiros, podendo ser aplicados em diferentes âmbitos ambientais e científicos.
Unique and specific features that are different from other environments characterize coastal areas with their morphodynamics being controlled by both natural processes and human intervention. An efficient coastal survey program is very important once the majority of the population is living in coastal areas. The correct management of these areas should include a detailed knowledge of the initial system characteristics in order to assess the evolution and the causes that affect coastal dynamics. In this work low cost coastal survey methods were applied in Belinho, Cepães and Fieiro Alto beaches, in the municipality of Esposende (northwest Portugal). Aerial photography obtained by UAV, photogrammetry techniques and 3D models using specific software, GPS mobile mapping and GIS technologies were developed in order to: (i) show the utility, efficiency and quality of 3D models in coastal survey and analysis; (ii) assess the coastal morphodynamics and evolution; (iii) define sediment growths or losses through volume measurements using these tools; (iv) compile and provide data for future research and survey. The results from this work show that the methodology applied is highly reliable and exact with a reasonable amount of detailed data being produced with low cost procedures. In this scope, all the information obtained is a useful and valuable tool for local coastal management and the methods can be applied in different areas.

Dissertação de mestrado em Geociências (área de especialização em Dinâmica Externa e Mudanças Globais)
O litoral constitui um ambiente muito dinâmico e muito sensível a impactes naturais e antrópicos. Nas últimas décadas, no litoral do NW de Portugal tem ocorrido uma erosão generalizada, manifestada essencialmente por migração das praias para o interior, perda de sedimentos e recuo das arribas. Embora natural, este processo tem sido agravado pela ação humana, sobretudo como consequência da implementação de obras de defesa costeira. É neste contexto que existe a necessidade de monitorizar e criar uma base de informação precisa de modo a suportar o planeamento e a gestão adequada destas áreas. A obtenção de dados úteis, fiáveis e de grande precisão permite conhecer e prever a evolução costeira, assim como prevenir potenciais consequências de planeamento e gestão deficientes. Neste trabalho aplicaram-se métodos de monitorização costeira de baixo custo nas praias de Ofir e Bonança, no concelho de Esposende. A fotografia aérea foi obtida através de VANT, procedendo-se a técnicas de fotogrametria e de modelação 3D recorrendo a mapeamento móvel com GPS e tecnologias SIG para: (i) demonstrar a utilidade, eficiência e qualidade de modelos tridimensionais para trabalhos de monitorização da orla costeira, (ii) avaliar tendências evolutivas da morfodinâmica costeira com recurso a modelos tridimensionais, (iii) efetuar medições de volumes para estudo de balanços sedimentares recorrendo a modelos tridimensionais e (iv) complementar, criar e prover dados para futuros estudos de monitorização. A análise dos resultados comprova uma intensa dinâmica do sistema praia-duna, com transporte sedimentar predominantemente no sentido NW-SE, devido ao vento marinho e à perda de areia na zona de contato berma da praia-duna por toda a área de estudo, mas principalmente na praia de Ofir.
The coastal zone is characterized by its intense morphodynamics and by the sensitivity to natural and anthropic impacts. In the last decades, the NW Portugal coastal zone has suffered generalized erosion, mainly expressed by inland beaches migration, sediment loss e cliffs retreat. Despite being a natural occurrence, this erosion is being enhanced by human activities largely as a consequence of the construction of coastal defence structures. Therefore the survey and development of a precise database is need to support an accurate planning and management in these areas. The acquisition of useful, reliable and exact data is essential to better knowledge and prediction in coastal evolution as to prevent wrong planning and management decisions. In this work low cost coastal survey methods were applied in Ofir and Bonança beaches, in the municipality of Esposende (northwest Portugal). Aerial photography obtained by UAV, photogrammetry techniques and 3D models using specific software, GPS mobile mapping and GIS technologies were developed in order to: (i) show the utility, efficiency and quality of 3D models in coastal survey and analysis; (ii) assess the coastal morphodynamics and evolution; (iii) define sediment growths or losses through volume measurements using these tools; (iv) compile and provide data for future research and survey. The results show an intense dynamics in the beach-dune system with sedimentary transport occurring mainly from NW to SE. This is due to the predominant sea winds and to the sand loss in the contact between the beach and the dune. It occurs in all the studied area but mainly in the Ofir beach.