Digital Photogrammetry Method Research Articles

Damage assessment of Siverek Castle during the Kahramanmaraş Earthquakes (Mw 7.7 and Mw 7.6) on 06 February 2023: Remediation and strengthening proposals

On February 6, 2023, two significant earthquakes with magnitudes (Mw) of 7.7 and 7.6 struck Turkey, occurring nine hours apart. In addition to the tragic loss of over 50,000 lives in the earthquakes centered in Kahramanmaraş, hundreds of thousands of engineering structures, such as residences, schools, hospitals, historical landmarks, highways, and more, were severely damaged. This study assesses the damages and risk scenario following the Kahramanmaraş earthquakes concerning Siverek Castle. In addition, remediation and strengthening proposals, required to eliminate the damage and the possible risk, have been developed. The initial stage involved observational damage assessments on the castle and surrounding slopes as part of field studies, identifying five different types of damage and potential risks. Subsequently, a precise 3D digital model of the damaged castle and its slopes was generated using the digital photogrammetry method. Additionally, geological and geophysical studies were conducted in the field to determine the characteristics of the mound structure, historical castle walls, soil and rock on the slope. Non-destructive, geophysical methods consisting Vertical Electrical Sounding (VES), Seismic Refraction Method (SRM) and Multichannel Analysis of Surface Waves (MASW) measurements were specifically employed in the area with historical remnants. To verify the obtained data, five boreholes were drilled in the lower parts of the slope, and experimental studies were conducted to determine the soil and rock material properties of the slope. In the numerical studies, a total of 54 2D stability analyses were performed under static, long-term static, and dynamic conditions. Additionally, 1000 different probabilistic rockfall analyses were conducted, both in 2D and 3D, to calculate the run-out distance, bounce height, velocity, and kinetic energies of the blocks that fell or were about to fall during the earthquake. In the final stage of the study, remediation and strengthening recommendations were prepared for the strengthening of the fortification walls and slopes where failures occurred, and stability analyses were conducted. Consequently, a design proposal recommending five distinct approaches to remediate and strengthen the castle and slopes impacted by the Kahramanmaraş earthquakes was endorsed by the relevant authorities, and construction has commenced. When the remediation and strengthening works are completed, the security of the cultural heritage will be ensured, and it is planned to be opened to visitors.

Influence of Material on the Density of a Point Cloud Created Using a Structured-Light 3D Scanner

Global digitization affects all sectors, including construction. Indeed, 3D scanning and digital photogrammetry methods are increasingly being used to obtain 3D data of buildings. The data obtained by these methods are a cloud of points, and our research is focused on this cloud’s density. From the literature and our own previous research, it is known that different materials have different properties that are manifested in the structured-light 3D scanning of the surface of the measured object. We have selected materials with the assumption that their properties would negatively affect the density of the point cloud. The article describes the methodology of how the measurement of selected materials was performed and suggests material surface treatment possibilities to improve the properties of the materials for structured-light 3D data acquisition. The influence of suggested surface treatments on objects and/or materials was not investigated. Each intended case of using the suggested surface treatments needs to be considered individually to avoid object deterioration and/or material deterioration. Thanks to this research, it is possible to estimate the problem areas in terms of the materials during the reconnaissance of the measured object. The results of our experiments show that the treatments used can improve the accuracy of the measured object model and reduce the need to manually complete the model or scan the measured object several times.

Evaluation of the Applicability of Digital Photogrammetry-Based Initial Imperfections on NLFEM Ultimate Strength Analysis of Ship- Type Stiffened Plates

In this study, the effects of initial imperfections on the ultimate strength values of ship-type stiffened plate structures are discussed and analysed from the point of view of how the initial imperfection forms are obtained. Ship stiffened panels are subjected to complex loading conditions during their operational lifespan. Accurate prediction of their strength and failure modes necessitates a thorough understanding of the effects of various imperfections on their behavior. Two primary sources of initial imperfections are considered: the buckling mode shapes resulting from linear eigenvalue buckling analysis and measurements based on digital photogrammetry. Buckling mode shapes, arising from the manufacturing process are extracted using linear static structural analysis. Digital photogrammetry is employed to capture and quantify imperfections by analysing high-resolution images of the physical structure. Numerical investigation is conducted by incorporating these two types of initial imperfections into non-linear finite element method (NLFEM) calculations. The buckling mode imperfections are applied as geometric perturbations, while the photogrammetry-based imperfections are incorporated as statistically representative deviations from the ideal geometry. Stiffened panel's structural response is analysed under longitudinal uniaxial compression. A new NLFEM project schematic has been utilized instead of the procedure outlined in the technical circular S.P 01/19 by Türk Loydu, which has been discontinued after ANSYS® Workbench™V.2019R2. This is proven by two validation case studies in ANSYS® Workbench™2022R2 version for considering buckling mode initial imperfections. A case study is then conducted using a 3D model of a stiffened plate panel, which is fabricated in a shipyard located in Trabzon, created by Photomodeler V. 2023.3.0.238 employing the digital photogrammetry method.NLFEM analysis is carried out for both initially deflected model after eigenvalue buckling analysis and naturally deflected model after welding operations. The comparative ultimate strength results are quite consistent, and this shows that the digital photogrammetric modelling method can be used in the analysis of ship structural elements.

Multi-Scenario Analysis of Rockfall Hazard for a Historical Vaulted Masonry Building in Sumela Monastery

ABSTRACT Sumela Monastery located in the northeast city of Trabzon is one of the most-visited touristic places in Turkey. As it is located in a mountainous area, rockfall hazards have become a crucial problem that the Monastery complex faces, especially in the last decade. Due to several rockfall cases, the monastery was closed for visitors in 2015 to take preventative measures. The current study examines the whole stages assessing and eliminating rockfall hazards that a historical Vaulted masonry building in the Sumela Monastery is exposed to. First of all, field studies were conducted to determine the kind and type of rockfall hazard. For this purpose, the regional geology of the area was evaluated and due to the inaccessibility of the region, industrial climbers were recruited to climb the slope above the Historical Vaulted building to determine the locations, dimensions, and risk level of the risky blocks that threatened the building. After that, the terrain of the risky area was modeled with Unmanned Aerial Vehicle (UAV) using the digital photogrammetry method. In the last step of the field studies, samples were taken to determine the mechanical and physical properties of the rocks and several laboratory tests were conducted. In the second part of the study, probabilistic analyses of 2400 rockfall simulations with eight different trajectories were conducted to calculate the maximum run-out distance, velocity, kinetic energy, and bounce heights of falling blocks. In the third part, to evaluate the damage status on the vaulted building, six different possible rockfall scenarios determined by the rockfall analysis were simulated using the Finite Element Method. After determining the rock block size that would not cause significant damage to the building, the cleaning and controlled removal method of the risky blocks was determined. In the last stage, controlled crushing and removing practices for risky rock blocks were carried out and the building was restored. Consequently, the rockfall hazard for the historical Vaulted building was eliminated and the monastery complex opened for visitors in 2021.

Preliminary Studies of the Coastal Defenses of Cullera’s Cape Built during the Spanish Civil War: From Historical Study to Formal Analysis

The Spanish Civil War is a chapter of a historical memory that has been avoided for years, rejecting any lived event. In recent years, this trend is changing, and public administrations are beginning to promote its recovery, starting by declaring this heritage as an Asset of Local Relevance. The aim of the current research is to study, analyze, and document the military constructions erected by the Government of the Republic during 1936–1939, at the Cullera’s Cape (Valencia). The research begins with the historical context definition, to subsequently approach the study of the material remains, analyzed after an exhaustive and rigorous graphic documentation work. The methodology followed had to be adapted to the needs of the constructions and their surroundings, which led to the use of a combination of 3D survey techniques based on terrestrial laser scanning and digital photogrammetry methods. Accordingly, we were able to digitize, geometrize, and document both the buried and the exposed construction remains, in a correct and precise manner. This is a unique and unprecedented investigation despite its significance and historical relevance. The present work can serve as a basis for the musealization of the site, contributing to its recovery and enhancement.

Growth trajectories of wild Assamese macaques (Macaca assamensis) determined from parallel laser photogrammetry

Socioecological factors are associated with life-history patterns and growth trajectories among primates. Under certain conditions, selection may favor a temporal decoupling of growth and major life-history events such as sexual maturation or natal dispersal. Yet, empirical tests of these associations in wild populations remain scarce owing to the lack of non-invasive methods to capture growth trajectories. In this study, we first compared two non-invasive methods of digital photogrammetry. Then, we used parallel laser photogrammetry to investigate forearm growth of wild Assamese macaque males and females in their natural habitat at Phu Khieo Wildlife Sanctuary, Thailand to test life-history and socio-ecological hypotheses. Across 48 males and 44 females, we estimated growth trajectories and pseudo-velocity curves by applying quadratic plateau models and non-parametric LOESS regressions. We assessed the development of sexual dimorphism by comparing the sexes at five different ages. Females had completed 96% of their growth at the age at first birth (5.9 years) and ceased growing at 7.1 years of age. Males, in contrast, grew until well after their average age of natal dispersal: they reached 81% of their size at the age of natal dispersal (4.0 years), and ceased growing only at 9.0 years of age, much later than females. Sexual dimorphism in forearm length was driven by an extended growth period in males, which is expected for males dispersing between multimale and multifemale groups and not facing the risk of being ousted by other larger males. Our results contradict the neonatal investment hypothesis that predicts a desynchronization of investment in growth and reproduction only in female baboons, but not other papionins producing cheaper neonates. Furthermore, male Assamese macaques do not delay natal dispersal until they are fully grown, in accordance with predictions of the male-career-framework for species with low to medium level of direct competition.

Application of combined terrestrial laser scanning and unmanned aerial vehicle digital photogrammetry method in high rock slope stability analysis: A case study

Recent advancements in remote sensing techniques have made it possible to overcome the risky issues using conventional methods and have opened up new opportunities for collecting data on discontinuity characteristics. This research compares the application of a Terrestrial Laser Scanner (TLS) and Unmanned Aerial Vehicle (UAV) in rock slope stability analysis. Two case studies, Ulu Choh Quarry and Jelapang Rock Slope are analysed using Kinematic Analysis and Slope Mass Rating (SMR) to depict rock through the 3D point cloud. The techniques are compared with the hand mapping method concerning the accuracy of the data acquisition in assessing the rock slope. The standard deviation for the dip and dip direction between digital capture and hand mapping is 2.97° and 2.86°, which falls under the acceptable tolerance limit. The integration of UAV and TLS also generates excellent clear point cloud data from the top to the toe of the slope.

Automatic feature type selection in digital photogrammetry of piping

AbstractA building information model for pipes already in place is essential in maintenance, for example, mending, reconstruction, and modernizing. However, current point cloud construction methods are not suited to complex piping systems, and many point cloud merging methods perform poorly in complex piping environments. To provide critical functions for constructing pipe point clouds from digital photogrammetry, a feature type selection network (FTSNet) is proposed. First, a digital photogrammetry method combining FTSNet with handcrafted features is proposed. Second, a piping data set of various piping scenes is constructed and evaluated using the developed data capturing device. A training data set and the corresponding network output categories are determined according to pose‐estimation performance using different image feature types. Finally, experiments conducted on the final test data set indicate that, together, digital photogrammetry and FTSNet can improve accuracy, flexibility, and processing speed.

Исследование точности определения геометрии рельсовой колеи железнодорожного пути методом цифровой фотограмметрии

The characteristics of the railway’s experimental section, geodetic networks and technologies types for their construction on the experimental section are considered. Technologies for studying railway geometry using a Gedo (Trimble) measuring trolley, a track template, and a geometric leveling method are presented. The technical characteristics of unmanned vehicles used for aerial photography of the experimental site, as well as the technical characteristics of the used cameras are given. The method and features of the experimental site aerial survey area using drones are described. The comparative accuracy of determining the geometric parameters of the railway track for processing digital images obtained from unmanned aerial vehicles by processing them on digital photogrammetric systems PHOTOMOD 6.5.2764?64 and “Agisoft Metashape Professional” is given. Based on the work performed, it is shown that the use of digital photogrammetry methods will enable quick and cost-effective determining the geometric parameters of the railway track for solving monitoring tasks, during reconstruction and major repairs in order to put it in the design position, etc.

Estimating a mathematical formula of soil erosion under the effect of rainfall simulation by digital close range photogrammetry technique

A new design of soil erosion and rainfall simulator is presented at this study as an attempt to deduce a mathematical formula of soil surface erosion phenomenon to describe the behavior of the sandy soil under the rainfall simulation, soil deformation such gullies and surface eroding rills are monitored by the Digital Close Range Photogrammetry (DCRP) technique that includes capturing digital images with a smart cellphone camera, and a Terrestrial Laser Scanner (TLS) to digitalize the soil surface as a smart point cloud data to produce Digital Elevation Models (DEM) with accuracy reaches 0.10 mm 3D surface model. The results show that the mentioned methods give typical digital surface feature express especially of using geometrical adjustment that controls the orientation of the digital surface, the digital imaging feature detection technology achieves accurate results despite its small cost compared to the laser scanner that the cost of imaging equipment and software are used did not exceed 12% of TLS cost. Results of the statistical observations, a 3 order polynomial mathematical formula was generated through the digital photogrammetry method that describes the sandy soil behavior under the rainfall simulation as a relation between the eroding rate and the duration through the different slopes.

МЕТОДЫ И ТЕХНОЛОГИИ АЭРОФОТОСЪЕМКИ И НАЗЕМНОЙ ФОТОГРАММЕТРИЧЕСКОЙ СЪЕМКИ ПРИ АРХЕОЛОГИЧЕСКИХ ИЗЫСКАНИЯХ

This article we consider methods and technologies of unmanned aerial surveying and close-range photogrammetric survey as applied for archeological research. We summed up the practical experience of the specialists of the Moscow State University of Geodesy and Cartography (MIIGAiK), obtained with the participation in the Bosporus archaeological expedition of the State Historical Museum on the Taman Peninsula in 2018–20. During the 3 expeditions, 18 archaeological sites were surveyed by aerial methods using UAV Geoscan 101 Geodesy and UAS DJI Phantom 4 Pro. In addition to aerial surveying, the Canon 30D digital camera with 50 mm and 14 mm focal lengths was used for groundbased, close-range photogrammetric surveys of archaeological sites. Some sites were surveyed many times during different periods of archaeological research. At all surveyed archaeological sites using photogrammetric processing methods at the Agisoft Metashape software we received survey documents (orthophoto, digital terrain models, 3D models). For some artifacts, three-dimensional metric models have been obtained using digital photogrammetry methods. Various methods of aerial surveying were used to study archaeological sites. The article gives recommendations on optimization of photography process in order to obtain reliable and informative documents for archaeological excavations. Comparison and analysis of aerial and close-range survey data was performed by the QGIS geographic information system. The information obtained using geo-information technologies will improve the quality and reliability of forecasts and hypotheses in archaeological studies.

Kuttu I, a recently discovered Old Turkic Altai runiform inscription and its reading and interpretation

The Old Turkic runiform inscription Kuttu I was found by B. M. Kindikov and A. G. Chekurashev in 2016 (Kindikov and Kindikov 2018: 35) at the footstep of the mountain Kuttu near the village Bichiktuu-Boom, known for its numerous Old Turkic inscriptions. The authors of this article documented it using the methods of digital photogrammetry in 2017. The article presents the first description of the inscription’s physical properties, as well as its transliteration, transcription and interpretation.

Triassic pentadactyl tracks from the Los Menucos Group (Río Negro province, Patagonia Argentina): possible constraints on the autopodial posture of Gondwanan trackmakers.

The Los Menucos locality in Patagonia, Argentina, bears a well-known ichnofauna mostly documented by small therapsid footprints. Within this ichnofauna, large pentadactyl footprints are also represented but to date were relatively underinvestigated. These footprints are here analyzed and discussed based on palaeobiological indications (i.e., trackmaker identification). High resolution digital photogrammetry method was performed to achieve a more objective representation of footprint three-dimensional morphologies. The footprints under study are compared with Pentasauropus from the Upper Triassic lower Elliot Formation (Stormberg Group) of the Karoo Basin (Lesotho, southern Africa). Some track features suggest a therapsid-grade synapsid as the potential trackmaker, to be sought among anomodont dicynodonts (probably Kannemeyeriiformes). While the interpretation of limb posture in the producer of Pentasauropus tracks from the Los Menucos locality agrees with those described from the dicynodont body fossil record, the autopodial posture does not completely agree. The relative distance between the impression of the digital (ungual) bases and the distal edge of the pad trace characterizing the studied tracks likely indicates a subunguligrade foot posture (i.e., standing on the last and penultimate phalanges) in static stance, but plantiportal (i.e., the whole foot skeleton and related soft tissues are weight-bearing) during the dynamics of locomotion. The reconstructed posture might have implied an arched configuration of the articulated metapodials and at least of the proximal phalanges, as well as little movement capabilities of the metapodials. Usually, a subunguligrade-plantiportal autopod has been described for gigantic animals (over six hundreds kilograms of body weight) to obtain an efficient management of body weight. Nevertheless, this kind of autopod is described here for large but not gigantic animals, as the putative trackmakers of Pentasauropus were. This attribution implies that such an autopodial structure was promoted independently from the body size in the putative trackmakers. From an evolutionary point of view, subunguligrade-plantiportal autopods not necessarily must be related with an increase in body size, but rather the increase in body size requires a subunguligrade or unguligrade, plantiportal foot. Chronostratigraphically, Pentasauropus was reported from Upper Triassic deposits of South Africa and United States, and from late Middle Triassic and Upper Triassic deposits of Argentina. Based on the stratigraphic distribution of the ichnogenus currently accepted, a Late Triassic age is here proposed for the Pentasauropus-bearing levels of the Los Menucos Group.

Remote sensing and photogrammetry techniques in diagnostics of concrete structures

Recently laser scanning technologies become widely used in many areas of the modern economy. In the following paper authors show a potential spectrum of use Terrestrial Laser Scanning (TLS) in diagnostics of reinforced concrete elements. Based on modes of failure analysis of reinforcement concrete beam authors describe downsides and advantages of adaptation of terrestrial laser scanning to this purpose, moreover reveal under which condition this technology might be used. Research studies were conducted by Faculty of Civil and Environmental Engineering at Gdansk University of Technology. An experiment involved bending of reinforced concrete beam, the process was registered by the terrestrial laser scanner. Reinforced concrete beam was deliberately overloaded and eventually failed by shear.Whole failure process was tracing and recording by scanner Leica ScanStation C10 and verified by synchronous photographic registration supported by digital photogrammetry methods. Obtained data were post-processed in Leica Cyclone (dedicated software) and MeshLab (program on GPL license). The main goal of this paper is to prove the effectiveness of TLS in diagnostics of reinforced concrete elements. Authors propose few methods and procedures to virtually reconstruct failure process, measure geometry and assess a condition of structure.

USE OF IMAGE BASED MODELLING FOR DOCUMENTATION OF INTRICATELY SHAPED OBJECTS

Abstract. In the documentation of cultural heritage, we can encounter three dimensional shapes and structures which are complicated to measure. Such objects are for example spiral staircases, timber roof trusses, historical furniture or folk costume where it is nearly impossible to effectively use the traditional surveying or the terrestrial laser scanning due to the shape of the object, its dimensions and the crowded environment. The actual methods of digital photogrammetry can be very helpful in such cases with the emphasis on the automated processing of the extensive image data. The created high resolution 3D models and 2D orthophotos are very important for the documentation of architectural elements and they can serve as an ideal base for the vectorization and 2D drawing documentation. This contribution wants to describe the various usage of image based modelling in specific interior spaces and specific objects. The advantages and disadvantages of the photogrammetric measurement of such objects in comparison to other surveying methods are reviewed.

USE OF IMAGE BASED MODELLING FOR DOCUMENTATION OF INTRICATELY SHAPED OBJECTS

In the documentation of cultural heritage, we can encounter three dimensional shapes and structures which are complicated to measure. Such objects are for example spiral staircases, timber roof trusses, historical furniture or folk costume where it is nearly impossible to effectively use the traditional surveying or the terrestrial laser scanning due to the shape of the object, its dimensions and the crowded environment. The actual methods of digital photogrammetry can be very helpful in such cases with the emphasis on the automated processing of the extensive image data. The created high resolution 3D models and 2D orthophotos are very important for the documentation of architectural elements and they can serve as an ideal base for the vectorization and 2D drawing documentation. This contribution wants to describe the various usage of image based modelling in specific interior spaces and specific objects. The advantages and disadvantages of the photogrammetric measurement of such objects in comparison to other surveying methods are reviewed.

Accuracy and reliability of 3D stereophotogrammetry: A comparison to direct anthropometry and 2D photogrammetry.

To evaluate the accuracy of three-dimensional (3D) stereophotogrammetry by comparing it with the direct anthropometry and digital photogrammetry methods. The reliability of 3D stereophotogrammetry was also examined. Six profile and four frontal parameters were directly measured on the faces of 80 participants. The same measurements were repeated using two-dimensional (2D) photogrammetry and 3D stereophotogrammetry (3dMDflex System, 3dMD, Atlanta, Ga) to obtain images of the subjects. Another observer made the same measurements for images obtained with 3D stereophotogrammetry, and interobserver reproducibility was evaluated for 3D images. Both observers remeasured the 3D images 1 month later, and intraobserver reproducibility was evaluated. Statistical analysis was conducted using the paired samples t-test, intraclass correlation coefficient, and Bland-Altman limits of agreement. The highest mean difference was 0.30 mm between direct measurement and photogrammetry, 0.21 mm between direct measurement and 3D stereophotogrammetry, and 0.5 mm between photogrammetry and 3D stereophotogrammetry. The lowest agreement value was 0.965 in the Sn-Pro parameter between the photogrammetry and 3D stereophotogrammetry methods. Agreement between the two observers varied from 0.90 (Ch-Ch) to 0.99 (Sn-Me) in linear measurements. For intraobserver agreement, the highest difference between means was 0.33 for observer 1 and 1.42 mm for observer 2. Measurements obtained using 3D stereophotogrammetry indicate that it may be an accurate and reliable imaging method for use in orthodontics.

Ways of improving the accuracy of digital aerial photography by the railway transport inventory

The development of railway sector around the world has always been a vital issue, as it plays important social, financial and economical role and influences the development of the country a lot. Because of constant growth and modernizing of the railway sector all processes and items of land and property fund have to be monitored. On the basis of the world experience, trends in the development of methods and technologies of area mapping it has been established that for the inventory of land and property fund objects cartographic material at 1 : 500 or 1 : 1000 scales suits the most. With the large amounts of work (for example area of mapping and number of railroad objects) it is reasonable to use digital aerial photography and technology of digital data processing, in particular methods of digital photogrammetry. In order to increase the accuracy of creating the cartographic component, the authors suggest, when choosing the parameters of aerial photography, taking into account spatial resolution of camera system, its geometrical properties, the influence of external factors and first of all the atmospheric refraction. It has been proved that by highly precise aerial photography the accuracy of fixation of angular elements of camera orientation with the help of Inertial Navigation Systems (INS) may be insufficient. Therefore it is recommended to thicken core network using block phototriangulation. This paper presents the description and results of experimental work, which helped to create cartographic material from digital images at 1 : 3000 scale with an accuracy of 4–5 cm, which fully meets the requirements for holding inventory, monitoring, maintenance, design and construction.

Experimental research on dynamic movement in strata overlying coal mines using similar material modeling

Dynamic movement within strata overlying coal mines and the distribution of the movement boundary are keenly investigated topics but are hampered by the difficulties of obtaining reliable monitoring data of movement within rock masses. The work presented in this paper combines physical experiments with a digital photogrammetry method to investigate these two topics. Two similar material model experiments were conducted, and a high-precision, close-range digital photogrammetry method was employed to observe movement in the model. The results, including dynamic movement tracking of targeted points, indicate the presence of six different movement areas in the overlying strata in the model. Based on motion vector directions determined for the model, the overlying strata were divided into three zones: (1) a zone with the movement vector oriented vertically downward, (2) a zone with the movement vector oriented towards the goaf center, and (3) a zone with the movement vector oriented towards the coal pillar. Dynamic movement tracking shows that all zones experienced an initial, active, and decline stage, but the timing, duration, and movement tracks are different for each zone. The overall analysis reveals that the movement boundary in the strata overlying the rock mass is not a straight line, but an S-shaped curve, in contrast to the traditional findings with respect to the movement boundary. These findings may prove significance in guiding better prediction of movement and deformation inside a given rock mass and related improvements in protecting engineered infrastructure.

Methods of digital photogrammetry in forest management in Slovakia

  The practical aspect of utilization of digital photogrammetry methods and their products in Slovak forestry is presented. We deal with the comparison of various data obtained by digital cameras, their accuracy, utilization and effectiveness for mapping. Based on presented results we summarize the main conclusions in the field of forest mapping. We also deal with the process of pan-sharpening for the preparation of image data for the interpretation and classification of forestry features. Also, the statistical characteristics of two photogrammetric projects with different geometric resolution photos (Ultracam D digital camera with ground sample distance of 10 cm and UltracamX digital camera with ground sample distance of 20 cm) from the same experimental area of the University Forest Enterprise Zvolen are described with the aim of finding an appropriate solution suitable for forest mapping. In both cases, the horizontal accuracy of the photogrammetric projects is presented. Finally, the process of true orthophoto generation and its utilization in forestry is the focus. Both experiments in this paper presented results which fulfil the accuracy standards defined by the state cadastre within the mapping of large scale maps. All projects, apart from the project of direct georeferencing, fulfilled the third accuracy class of mapping, so they can be used within cadastral mapping, land consolidations and, of course, within forested land mapping. Still, all the projects meet the accuracy requirements within the forest mapping standard, where the forestry features and forest spatial distribution units are mapped.