Showing papers on "Photogrammetry published in 2006"

Image-based 3d modelling: a review

Abstract: In this paper the main problems and the available solutions are addressed for the generation of 3D models from terrestrial images. Close range photogrammetry has dealt for many years with manual or automatic image measurements for precise 3D modelling. Nowadays 3D scanners are also becoming a standard source for input data in many application areas, but image-based modelling still remains the most complete, economical, portable, flexible and widely used approach. In this paper the full pipeline is presented for 3D modelling from terrestrial image data, considering the different approaches and analysing all the steps involved.

Digital camera calibration methods: Considerations and comparisons

Abstract: Camera calibration has always been an essential component of photogrammetric measurement, with self-calibration nowadays being an integral and routinely applied operation within photogrammetric triangulation, especially in high-accuracy close-range measurement. With the very rapid growth in adoption of off-the-shelf digital cameras for a host of new 3D measurement applications, however, there are many situations where the geometry of the image network will not support robust recovery of camera parameters via on-the-job calibration. For this reason, stand-alone camera calibration has again emerged as an important issue in close-range photogrammetry, and it also remains a topic of research interest in computer vision. This paper overviews the current approaches adopted for camera calibration in close-range photogrammetry and computer vision, and discusses operational aspects for self-calibration. Also, the results of camera calibrations using different algorithms are summarized. Finally, the impact of chromatic aberration on modelled radial distortion is touched upon to highlight the fact that there are still issues of research interest in the photogrammetric calibration of consumer-grade digital cameras.

Digital image correlation: performance and potential application in photogrammetry

Abstract: A procedure for digital image correlation is described which is based on least squares window matching. The immediate aim is high precision parallax assessment, point transfer, and point measurement. Experiments and theory have confirmed the high accuracy potential of the method. By implementation of charge coupled device (CCD) video cameras in an analytical plotter, an experimental hardware and software configuration has been established with which the operational on line application of digital image correlation for conventional photogrammetric measuring tasks can be tested. First results of calibration and performance of the system are presented. They allow optimistic conclusions as to the further development and practical application of digital image processing in photogrammetry.

Close Range Photogrammetry Principles, Methods and Applications

Abstract: The book covers the field of close-range photogrammetry which has diverse fields of application such as manufacturing engineering (e.g. shape verification and reverse engineering), and medicine and entertainment (motion capture and analysis). It provides detailed overviews of analytical methods (e.g. bundle adjustment and image processing), commercial photogrammetric systems and applications.

Multi-image matching for DSM generation from IKONOS imagery

Abstract: High-resolution satellite images at sub-5-m footprint, such as IKONOS and SPOT5 HRG/HRS images, are becoming increasingly available to the earth observation community and their respective clients. The related cameras all use linear array CCD technology for image sensing. The processing of these kinds of images provides a challenge for algorithmic redesign and this offers the possibility of reconsidering and improving many photogrammetric processing components. This contribution presents an advanced matching approach for automatic DSM generation from high-resolution satellite images. It can provide dense, precise and reliable results. The method matches multiple (more than two) images simultaneously and it uses a coarse-to-fine hierarchical solution with an effective combination of several image matching algorithms and automatic quality control. The DSMs are generated by a combination of matching results of feature points, grid points and edges. The proposed approach has been applied to IKONOS images over a testfield in Thun, Switzerland with accurate ground control points, a 1600-m height range and variable land cover, but with sub-optimal imaging conditions (snow, long shadows). The accuracy tests are based on the comparison between the reference data from an airborne laser scanner and the automatically extracted DSMs. The RMS errors for the whole area, excluding trees and bushes, are 2–3 m, while for bare ground the accuracy is about 1 m or even better.

Photogrammetric techniques in civil engineering material testing and structure monitoring

Abstract: Civil engineering material testing includes a wide range of applications requiring the determination of the threedimensional shape of an object and changes thereof. Large structure monitoring will often include the necessity of determining object deformations at a large number of points. Photogrammetric techniques offer a large potential for the solution of a wide range of measurement tasks in this field. A modular toolbox consisting of digital cameras, computer interfaces, illumination systems, calibration devices, combined with subpixel accuracy image measurement operators, multi-image matching techniques, and self-calibrating bundle adjustment in a suitable user interface, depicts a very powerful tool for tailoring custom-made solutions for material testing labs. Due to the wide range and the repetitive nature of measurements tasks in civil engineering, these applications could depict a significant future market for photogrammetry. This paper will briefly discuss the major hardware and software modules of a toolbox for civil engineering material testing and large structure monitoring. Based on several sample applications covering object dimensions from 10 cm to 500 meters, the potential of photogrammetric deformation measurement techniques will be shown. The major advantage of photogrammetric techniques can often be seen in the fact that they allow for highly automated measurements at a large number of points simultaneously. In many cases, object deformations can be determined at a precision in the order of 1:100,000 of the object dimension, based on off-theshelf hardware components.

Manual of Photogrammetry, 5th Edition

Abstract: Control of land subdivision, a manual of subdivision regulations for Evidence & Procedures for Boundary Location, 6th Edition Brown, Robillard & Wilson Elements of Photogrammetry with Application in GIS, 4th Edition, 2014, Wolf, DeWitt. The 2015 Photogrammetric Award (Fairchild) is awarded to Prof. on computer vision in the 5th and 6th edition of the ASPRS Manual of Photogrammetry. Bottleneck of photogrammetry = massive manual data processing, Agisoft PhotoScan (Standard / Professional edition) 6th International Workshop.

Method and apparatus for panoramic imaging

Abstract: Camera system and methods to capture panoramic imagery from a camera mounted on a moving platform, using low-cost digital image sensors. The panoramic imagery appears seamless and natural to the eye. The panoramic imaging system and methods are specifically designed to accommodate the long acquisition times of low-cost digital image sensors, despite the motion of the camera during image capture. Pairs of cameras are arranged about an axis and a pairwise firing sequence enables capturing a series of adjacent images without gap or overlap. Additionally, when combined with suitable supplemental sensors, the image data provide location information about objects in the image for use in elementary photogrammetry.

Registration of terrestrial laser scanner data using imagery

Abstract: Building 3D models using terrestrial laser scanner (TLS) data is currently an active area of research, especially in the fields of heritage recording and site documentation. Multiple TLS scans are often required to generate an occlusion-free 3D model in situations where the object to be recorded has a complex geometry. The first task associated with building 3D models from laser scanner data in such cases is to transform the data from the scanner’s local coordinate system into a uniform Cartesian reference datum, which requires sufficient overlap between the scans. Many TLS systems are now supplied with an SLR-type digital camera, such that the scene to be scanned can also be photographed. The provision of overlapping imagery offers an alternative, photogrammetric means to achieve point cloud registration between adjacent scans. The images from the digital camera mounted on top of the laser scanner are used to first relatively orient the network of images, and then to transfer this orientation to the TLS stations to provide exterior orientation. The proposed approach, called the IBR method for Image-Based Registration, offers a one-step registration of the point clouds from each scanner position. In the case of multiple scans, exterior orientation is simultaneously determined for all TLS stations by bundle adjustment. This paper outlines the IBR method and discusses test results obtained with the approach. It will be shown that the photogrammetric orientation process for TLS point cloud registration is efficient and accurate, and offers a viable alternative to other approaches, such as the well-known iterative closest point algorithm.

Small Format Aerial Photography

Abstract: Geometry of a single photograph geometry of stereo photography mapping and measuring from single photographs stereoscopic mapping and measuring practical considerations survey techniques for small-format photography small-format instruments and photographic films electronic (digital) imagery camera platforms camera mounts mission planning operational procedures air-survey navigation multispectral photography urban survey small-format photogrammetric surveys small-format aerial photography for natural resources small-format aerial photography for the environment large-scale map revision from digital cameras.

Zoom-dependent camera calibration in digital close-range photogrammetry

Abstract: One of the well-known constraints applying to the adoption of consumer-grade digital cameras for photogrammetric measurement is the requirement to record imagery at fixed zoom and focus settings. The camera is then calibrated for the lens setting employed. This requirement arises because calibration parameters vary significantly with zoom/focus setting. In this paper, a zoom-dependent calibration process is proposed whereby the image coordinate correction model for interior orientation and lens distortion is expressed as a function of the focal length written to the EXIF header of the image file. The proposed approach frees the practitioner from the requirement to utilize fixed zoom/focus settings for the images forming the photogrammetric network. Following a review of the behavior of camera calibration parameters with varying zoom settings, an account of the newly developed zoom-dependent calibration model is presented. Experimental results of its application to four digital cameras are analysed. These show that the proposed approach is suited to numerous applications of medium-accuracy, digital, close-range photogrammetry.

Geometric test field calibration of digital photogrammetric sensors

Abstract: Test field system calibration will be a fundamental part of the future photogrammetric production line. Accurate calibration and performance evaluations are necessary for fully assessing the stability and accuracy of digital sensing techniques. In this paper, a method of comprehensive geometric calibration in a test field has been developed and empirically tested using eight image blocks collected with three UltraCamD digital large format photogrammetric cameras. Permanent photogrammetric test fields form the basis of the method. Important components of the method are determination of system parameters, evaluation of systematic errors, and assessment of geometric accuracy. The results showed that UltraCamD images contained systematic deformations that could not be modeled with single lens additional parameter models. Good point determination accuracy was obtained despite the systematic errors; the typical accuracy was 2–3 μm in image space in the horizontal coordinates and 0.05–0.09‰ of the object distance in height. One of the cameras had significantly poorer performance. In the worst cases, the horizontal accuracy was 5 μm in image space and the height accuracy was 0.18‰ of the object distance. The analog cameras gave better results than the UltraCamD, but the development of appropriate mathematical models for UltraCamD as well as improvements in digital sensors may change the situation in the near future.

Sea Ice Monitoring by Remote Sensing

Abstract: Reprinted with permission from The American Society for Photogrammetry & Remote Sensing. Sandven, S. and O.M. Johannesen. “Sea Ice Monitoring by Remote Sensing.” Manual of Remote Sensing: Remote Sensing of the Marine Environment. James F.R. Gower, ed. 3rd Edtion, volume 6. Bethesda: American Society for Photogrammetry & Remote Sensing, 2006. 241-283. This article originally appeared as chapter 8 in the Manual of Remote Sensing, vol. 6, 3rd edition: Remote Sensing of the Marine Environment. The entire volume is available for purchase at www.asprs.org.

Oblique photogrammetry with visible and thermal images of active lava flows

Abstract: Digital images from hand-held cameras are increasingly being acquired for scientific purposes, particularly where non-contact measurement is required. However, they frequently consist of oblique views with significant camera-to-object depth variations and occlusions that complicate quantitative analyses. Here, we report the use of oblique photogrammetric techniques to determine ground-based thermal camera orientations (position and pointing direction), and to generate scene information for lava flows at Mount Etna, Sicily. Multiple images from a consumer grade digital SLR camera are used to construct a topographic model and reference associated ground-based thermal imagery. We present data collected during the 2004–2005 eruption and use the derived surface model to apply viewing distance corrections (to account for atmospheric attenuation) to the thermal images on a pixel-by-pixel basis. For viewing distances of ~100 to 400 m, the corrections result in systematic changes in emissive power of up to ±3% with respect to values calculated assuming a uniform average viewing distance across an image.

Digital photogrammetry and laser rangefinder techniques to measure African elephants : research article

Abstract: Photogrammetry can be used to measure the body dimensions of a variety of mammals. We developed a digital photogrammetry technique and used an infrared laser rangefinder to measure the shoulder heights of African elephants ( Loxodonta africana ). Measures of the height of objects of known size using digital photogrammetry were between 0.7% shorter to 0.6% taller than the real values. The rangefinder recorded values that ranged from 0.8% to 3.6% larger than the real height. When we applied digital photogrammetry to tame elephants, measured shoulder heights were 1.6% to 3.4% shorter than those recorded using a custom- made calliper. For these elephants, the rangefinder recorded shoulder heights that were 3.8 to 9.4% smaller than the real values. The digital photogrammetric technique described here is less time-consuming and as or more precise than other techniques used to measure African elephants.

The accuracy of grid digital elevation models linearly constructed from scattered sample data

Abstract: In this paper, a theoretical‐empirical model is developed for modelling the accuracy of a grid digital elevation model (DEM) linearly constructed from scattered sample data. The theoretical component integrates sample data accuracy in the model by means of the error‐propagation theory. The empirical component seeks to model what is known as information loss, i.e. the sum of the error due purely to sampling the continuous terrain surface with a finite grid interval and the interpolation error. For this purpose, randomly spaced data points, supposed to be free of error, were converted into regularly gridded data points using triangulation with linear interpolation. Original sample data were collected with a 2×2 m sampling interval from eight different morphologies, from flat terrain to highly rugged terrain, applying digital photogrammetric methods to large‐scale aerial stereo imagery (1 : 5000). The DEM root mean square error was calculated by the true validation method over several sets of check points, o...

Statistical concepts and their application in photogrammetry and surveying

Abstract: This paper was prepared as supporting documentation for a tutorial given by the authors under Photogrammetric Society auspices. The authors do not make any claims of novelty or innovation but they feel that the information contained in the paper will provide useful study material, especially for practitioners of photogrammetry and surveying. The following topics are covered: functional and stochastic models; the least squares process; statistical testing; optimal design methods; and numerical examples in the design of a horizontal control network and of a close range photogrammetric survey.

Industrial photogrammetry: new developments and recent applications

Abstract: Over the past decade, photogrammetry has been increasingly applied as a precise three dimensional measuring tool in industrial and engineering works. Analytical photogrammetry is now routinely employed in tasks of measurement as diverse as machine tool inspection and fixture checking, structural deformation monitoring, the provision of control databases to guide industrial robots and the measurement of structures in earth orbit. Traditional photogrammetric techniques and instrumentation are usually inappropriate for industrial work and the development of complete, fully integrated close range photogrammetric systems has recently gained considerable impetus. This paper details some of the significant new developments in industrial photogrammetry, with particular reference to technological advances in the Simultaneous Triangulation and Resection System (STARS) designed by Geodetic Services, Inc. for industrial photograininetry. Practical aspects of industrial measurement are also presented in a review of some of the varying tasks that GSI has carried out in recent years. Emphasis is placed on demonstrating the flexibility, accuracy, reliability and economy of photogrammetry, as well as the progress made in automating this measurement technique.

DEM generation from SPOT-5 3-fold along track stereoscopic imagery using autocalibration

Abstract: This paper describes the derivation and accuracy assessment of Digital Elevation Models (DEM) from 3-fold along-track stereoscopic SPOT-5 imagery. The work was conducted in the scope of the HRS (Haute Resolution Stereoscopique)-Scientific Assessment Program, organized by the Centre National d'Etudes Spatiales (CNES) and the International Society of Photogrammetry and Remote Sensing (ISPRS). The orientation of the SPOT-5 image scene is reconstructed by bundle adjustment using ground control points. The functional model is based on correction polynomials and permits autocalibration. At 17 independent check points a RMS-error of 2 m was achieved. DEM are produced in two different ways: The more rigorous way employs an automatic region growing image matching process generating a dense point cloud in image space, transforms it into the object space using the estimated model parameters and converts it into a regular grid DEM. In a second approach the commercial software ISAE and rational functions are applied. The comparison with a digital terrain model (DTM) of superior accuracy yields standard deviations better than 5 m in flat and moderate terrain and better than 10 m in mountainous regions. With ISAE a DEM for the entire image area (approx. 60 × 80 km) is produced with a standard deviation of approximately 8 m. All grid points were generated fully automatically, i.e. the presented standard deviations still include the effect of large differences between the produced DEM and the DTM.

Modelling of chromatic aberration for high precision photogrammetry

Abstract: Chromatic aberration appears for almost all lenses for imaging based on white light. The effect degrades image quality for both b/w and colour cameras. This paper discusses the possibilities of modelling chromatic aberration with self-calibrating bundle adjustment for high-precision photogrammetric 3D point measurement using all three channels of a true colour image. After a survey on common types of digital colour sensors, wave-length dependent imaging errors of usual lenses are discussed. Consequently, different options for the correction of the occurring effects are derived. The resulting effect on image and object accuracy is verified by various test field calibrations using different combinations of digital colour cameras and lenses. For standard imaging configurations in close-range photogrammetry, a significant enhancement of inner precision by a factor of 1.7 can be proven. It can be shown that the length measurement error for standardized imaging configurations can be improved slightly whereby final results are still on investigation.

The application of photogrammetry, remote sensing and geographic information systems (gis) to fossil resource management

Abstract: Change is one of the many challenges facing fossil resource managers today. This concept is not restricted to physical alterations affecting the resource such as erosion, visitation, vandalism or even preservation. Changes in the views of the public, policies of an administration and in the field of geospatial technology are also greatly affecting how a particular resource program or significant locality is managed. Geospatial technologies are changing and evolving at an incredible rate, resulting in not only an increase in capability, but also of complexity and expectations for the resulting product. Today, it is not uncommon to integrate a number of geospatial tools, some of which require a sophisticated knowledge of computer systems, data requirements and techniques. This is not necessarily a negative, as it sets the foundational need for partnerships with other resource specialists, academic researchers and the public across disciplines, across administrative boundaries and across agencies. Within the cadre of geospatial technologies, there are a number of tools that can greatly streamline and support land management decisions and the implementation of these decisions. These tools include utilizing imagery data sets through photogrammetry (the art and science of making measurements from photographs) and analyzing remotely sensed data. Data sets may be collected through active sensors, such as RADAR or LIDAR, or passive sensors, which collect multior hyperspectral imagery. The processing of these data sets can result in detailed data files representing the terrain or geological and soil maps, to name only a few. Data sets can be combined with both coordinate and attribute data collected in the field and processed geospatially using Geographic Information Systems, a combination of computer hardware, software and data that allows information to be organized around a specific location. At paleontological localities such as the Red Gulch Dinosaur Tracksite, Twentymile Wash Dinosaur Tracksite and Picketwire Canyonlands Dinosaur Tracksite innovative geospatial technologies were tested, refined and integrated. This integrated approach not only resulted in documentation of the paleontological resource, but also supplied products used in site development, resource protection and interpretation.

Innovations in 3D geo information systems

Abstract: Keynotes.- 3D Geometries in Spatial DBMS.- A Web 3D Service for Navigation Applications.- 3D Spatial Data Acquisition - LIDAR and Digital Photogrammetry.- Integration of Photogrammetric and LIDAR Data in a Multi-Primitive Triangulation Environment.- LIDAR-Aided True Orthophoto and DBM Generation System.- Surface Matching Strategy for Quality Control of LIDAR Data.- On-line Integration of Photogrammetry and GIS to Generate Fully Structured Data for GIS.- 3D Spatial Data Modelling and Representation.- 3D Integral Modeling for City Surface & Subsurface.- Spatial Object Structure for Handling 3D Geodata in GRIFINOR.- The Study and Application of Object-oriented Hyper-graph Spatio-temporal Reasoning Model.- Using 3D Fuzzy topological relationships for Checking of Spatial Relations between Dynamic Air Pollution Cloud and City Population Density.- 3D Modeling Moving Objects under Uncertainty Conditions.- Research on a feature based spatio-temporal data model.- 0-D Feature in 3D Planar Polygon Testing for 3D Spatial Analysis.- Definition of the 3D content and geometric level of congruence of numeric cartography.- 3D multi-scale modelling of the interior of the Real Villa of Monza (ITALY).- 3D GIS Frameworks.- On The Road To 3D Geographic Systems: Important Aspects of Global Model-Mapping Technology.- Cristage: A 3D GIS with A Logical Crystallographic Layer To Enable Complex Analyses.- The Democratizing Potential of Geographic Exploration Systems (GES) Through the Example of GRIFINOR.- The Integration Methods of 3D GIS and 3D CAD.- 3D Navigation for 3D-GIS - Initial Requirements.- Web-based GIS-Transportation Framework Data Services using GML, SVG and X3D.- 3D Geo-database Implementation using Craniofacial Geometric Morphometrics Database System.- GIS-based Multidimensional Approach for Modeling Infrastructure Interdependency.- Conception of a 3D Geodata Web Service for the Support of Indoor Navigation with GNSS.- 3D Objects Reconstruction.- Reconstruction of 3D Model Based on Laser Scanning.- Automatic Generation of Pseudo Continuous LoDs for 3D Polyhedral Building Model.- Reconstruction of Complex Buildings using LIDAR and 2D Maps.- Building Reconstruction - Outside and In.- Skeletonization of Laser-Scanned Trees in the 3D Raster Domain.- Automated 3D Modeling of Buildings in Suburban Areas Based on Integration of Image and Height Data.- Automatically Extracting 3D Models and Network Analysis for Indoors.- 3D City Modelling.- Improving the Realism of Existing 3D City Models.- Different Quality Level Processes and Products for Ground-based 3D City and Road Modeling.- Texture Generation and Mapping Using Video Sequences for 3D Building Models.- Design and Implementation of Mobile 3D City Landscape Authoring/Rendering System.- Macro to Micro Archaeological Documentation: Building a 3D GIS Model for Jerash City and the Artemis Temple.- Building 3D GIS Modeling Applications in Jordan: Methodology and Implementation Aspects.- 3D Mapping, Cadastre and Utility.- Moving Towards 3D - From a National Mapping Agency Perspective.- An Approach for 3D Visualization of Pipelines.- Developing Malaysian 3D Cadastre System - preliminary findings.- Developing 3D Registration System for 3D Cadastre.- 3D Visualization.- Volumetric Spatiotemporal Data Model.- Use of 3D Visualization in Natural Disaster Risk Assessment for Urban Areas.- Development and Design of 3D Virtual Laboratory for Chemistry Subject Based on Constructivism-Cognitivism-Contextual Approach.- The 3D Fusion and Visualization of Phototopographic Data.- Integrating a Computational Fluid Dynamics Simulation and Visualization with a 3D Virtual Walkthrough - A Case Study of Putrajaya.- A Geospatial Approach to Managing Public Housing on Superlots.- 3D Visualization and Virtual Reality for Cultural Heritage Diagnostic.- 3D Terrain Modeling and Digital Orthophoto Generation.- True Ortho-photo Generation from High Resolution Satellite Imagery.- Development of Country Mosaic Using IRS-WiFS Data.- Digital Terrain Models Derived from SRTM Data and Kriging.- The St Mark's Basilica Pavement: The Digital Orthophoto 3D Realisation to the Real Scale 1:1 for the Modelling and the Conservative Restoration.- The Application of GIS in Maritime Boundary Delimitation.- Integration of GIS and Digital Photogrammetry in Building Space Analysis.- An Integration of Digital Photogrammetry and GIS for Historical Building Documentation.- Reconstruction of Three Dimensional Ocean Bathymetry Using Polarised TOPSAR Data.

Integration of laser scanning and photogrammetry for heritage documentation

Abstract: 2

Geometrically accurate time series of archived aerial images and airborne lidar data in a forest environment

Abstract: Reconstructing three-dimensional structural changes in the forest over time is possible using archived aerial photographs and photogrammetric techniques, which have recently been introduced to a larger audience with the advent of digital photogrammetry. This paper explores the feasibility of constructing an accurate time-series of archived aerial photographs spanning 42 years using different types of geometric data and estimation methods for image orientation. A recent airborne laser scanning (lidar) data set was combined with the image block and assessed for geometric match. The results suggest that it is possible to establish the multitemporal geometry of an image block to an accuracy that is better than 0.5 m in 3D and constant over time. Even geodetic ground control points can be omitted from the estimation if the most recent images have accurate direct sensor orientation, which is becoming a standard technique in aerial photography. This greatly reduces the costs and facilitates the work. An accurate multitemporal image block combined with recent lidar scanning for the estimation of topography allows accurate monitoring and retrospective analysis of forest vegetation and management operations.

Approximate direct georeferencing in national coordinates

Abstract: Direct georeferencing has gained an increasing importance in photogrammetry and remote sensing. Thereby, the parameters of exterior orientation (EO) of an image sensor are determined by GPS/INS, yielding results in a global geocentric reference frame. Photogrammetric products like digital terrain models or orthoimages, however, are often required in national geodetic datums and mapped by national map projections, i.e., in “national coordinates”. As the fundamental mathematics of photogrammetry is based on Cartesian coordinates, the scene restitution is often performed in a Cartesian frame located at some central position of the image block. The subsequent transformation to national coordinates is a standard problem in geodesy and can be done in a rigorous manner–at least if the formulas of the map projection are rigorous. Drawbacks of this procedure include practical deficiencies related to the photogrammetric processing as well as the computational cost of transforming the whole scene. To avoid these problems, the paper pursues an alternative processing strategy where the EO parameters are transformed prior to the restitution. If only this transition was done, however, the scene would be systematically distorted. The reason is that the national coordinates are not Cartesian due to the earth curvature and the unavoidable length distortion of map projections. To settle these distortions, several corrections need to be applied. These are treated in detail for both passive and active imaging. Since all these corrections are approximations only, the resulting technique is termed “approximate direct georeferencing”. Still, the residual distortions are usually very low as is demonstrated by simulations, rendering the technique an attractive approach to direct georeferencing.

Combining laser scanning and photogrammetry: a hybrid approach for heritage documentation

Abstract: High quality 3D models of cultural heritage sites can be generated efficiently by laser scanning, which allows the accurate and dense measurement of surface geometry. In addition to the geometric data collection, texture mapping based on additionally collected digital imagery is particular important for this type of application. This requires a combined processing of range and image data sets. For this purpose, they have to be registered or aligned by a suitable transformation to a common reference coordinate system. The involved transformation parameters can be determined based on corresponding elements to be extracted from the different data sets. In the paper an efficient edge detection algorithm is presented, which allows for the automatic segmentation of such primitives even in complex scenes. In order to achieve a high quality 3D photo-realistic mode,l this alignment process has to be followed by an automatic texture mapping, which is discussed in the second part of the paper. The presented algorithms are demonstrated in the framework of a project aiming at the generation of a 3D virtual model of the Al-Khasneh, a well-known monument in Petra, and a Roman Theatre in ancient Jerash city, Jordan.

Digital photogrammetry and laser rangefinder techniques to measure African elephants

Abstract: Photogrammetry can be used to measure the body dimensions of a variety of mammals. We developed a digital photogrammetry technique and used an infrared laser rangefinder to measure the shoulder heights of African elephants (Loxodonta africana). Measures of the height of objects of known size using digital photogrammetry were between 0.7% shorter to 0.6% taller than the real values. The rangefinder recorded values that ranged from 0.8% to 3.6% larger than the real height. When we applied digital photogrammetry to tame elephants, measured shoulder heights were 1.6% to 3.4% shorter than those recorded using a cus- tom-made calliper. For these elephants, the rangefinder recorded shoulder heights that were 3.8 to 9.4% smaller than the real values. The digital photogrammetric technique described here is less time-consuming and as or more precise than other techniques used to measure African elephants.

Study on Reverse Engineering of Historical Architecture Based on 3D Laser Scanner

Abstract: Repair and maintenance of historical architecture includes reinforcement of configuration, repair of figure and so on. All these need surveying information such as blueprint etc. 3D laser scanning technology is one of the important technique methods to acquire spatial data. It scans the architecture point by point quickly; registers and joints point cloud to simulate the shape by computer; reconstructs 3D model accurately finally. It also produces construction drawing including ichnography, elevation, and cutaway. In addition, detail structure and vignette can be got by close-range photogrammetry method, which produces the orthoimage and linear drawing. This method is especially fit for surveying historical architecture that lacks construction records.