CAD Drawings Research Articles

BUILDING CONSTRUCTION PROGRESS MONITORING USING UNMANNED AERIAL SYSTEM (UAS), LOW-COST PHOTOGRAMMETRY, AND GEOGRAPHIC INFORMATION SYSTEM (GIS)

Abstract. Monitoring the progress of building’s construction is critical in construction management. However, measuring the building construction’s progress are still manual, time consuming, error prone, and impose tedious process of analysis leading to delays, additional costings and effort. The main goal of this research is to develop a methodology for building construction progress monitoring based on 3D as-built model of the building from unmanned aerial system (UAS) images, 4D as-planned model (with construction schedule integrated) and, GIS analysis. Monitoring was done by capturing videos of the building with a camera-equipped UAS. Still images were extracted, filtered, bundle-adjusted, and 3D as-built model was generated using open source photogrammetric software. The as-planned model was generated from digitized CAD drawings using GIS. The 3D as-built model was aligned with the 4D as-planned model of building formed from extrusion of building elements, and integration of the construction’s planned schedule. The construction progress is visualized via color-coding the building elements in the 3D model. The developed methodology was conducted and applied from the data obtained from an actual construction site. Accuracy in detecting ‘built’ or ‘not built’ building elements ranges from 82–84 % and precision of 50–72 %. Quantified progress in terms of the number of building elements are 21.31% (November 2016), 26.84 % (January 2017) and 44.19 % (March 2017). The results can be used as an input for progress monitoring performance of construction projects and improving related decision-making process.

Design and Manual to Construct Rainout-Shelters for Climate Change Experiments in Agroecosystems

Climate change models predict reduced summer precipitations for most European countries, including more frequent and extreme summer droughts. Rainout-shelters which intercept part of the natural precipitation provide an effective tool to investigate effects of different precipitation levels on biodiversity and ecosystem functioning. In this study, we evaluate and describe in detail a fixed-location rainout shelter (2.5×2.5m) with partial interception of natural rainfall. We provide a complete parts list, a construction manual and detailed CAD drawings allowing to rebuild and use these shelters for rainfall manipulation studies. In addition, we describe a rainout-shelter control treatment giving the possibility to quantify and account for potential shelter artifacts. To test the rainout-shelters, we established the following three treatments each in eight winter wheat plots of the agricultural long-term farming system comparison trial DOK in Therwil (Switzerland): (1) A rainout-shelter with 65% interception of rainfall, (2) a rainout-shelter control without interception of rainfall, and (3) an ambient control. The rainout-shelter effectively excluded 64.9% of the ambient rainfall, which is very close to the a priori calculated exclusion of 65.1%. In comparison to the ambient control plots, gravimetric soil moisture decreased under the rainout-shelter by a maximum of 11.1 percentage points. Air temperature under the rainout-shelter differed little from the ambient control (−0.55◦C in 1.2m height and +0.19◦C in 0.1m height), whereas soil temperatures were slightly higher in periods of high ambient temperature (+1.02◦C), but remained basically unaffected in periods of low ambient temperature (+0.14◦C). A maximum edge effect of 0.75m defined a sampling area of 1 × 1m under the rainout-shelter. The rainout-shelters presented here, proved to sustain under heavy weather and they were well-suited to be used in agricultural fields where management operations require the removal of the rainout-shelters for management operations. Overall, the results confirmed the good performance of the presented rainout-shelters regarding rainout-shelter artifacts, predictable rain exclusion, and feasibility for experimental studies in agricultural fields.

Initial evaluation of Advanced Collapsed cone Engine dose calculations in water medium for I‐125 seeds and COMS eye plaques

To investigate the dose calculation accuracy in water medium of the Advanced Collapsed cone Engine (ACE) for three sizes of COMS eye plaques loaded with low-energy I-125 seeds. A model of the Oncura 6711 I-125 seed was created for use with ACE in Oncentra® Brachy (OcB) using primary-scatter separated (PSS) point dose kernel and Task Group (TG) 43 datasets. COMS eye plaque models of diameters 12, 16, and 20mm were introduced into the OcB applicator library based on 3D CAD drawings of the plaques and Silastic inserts. To perform TG-186 level 1 commissioning, treatment plans were created in OcB for a single source in water and for each COMS plaque in water for two scenarios: with only one centrally loaded seed, or with all seed positions loaded. ACE dose calculations were performed in high accuracy mode with a 0.5×0.5×0.5mm3 calculation grid. The resulting dose data were evaluated against Monte Carlo (MC) calculated doses obtained with MCNP6, using both local and global percent differences. ACE doses around the source for the single seed in water agreed with MC doses on average within <5% inside a 6×6×6cm3 region, and within <1.5% inside a 2×2×2cm3 region. The PSS data were generated at a higher resolution within 2cm from the source, resulting in this improved agreement closer to the source due to fewer approximations in the ACE dose calculation. Average differences in both investigated plaque loading patterns in front of the plaques and on the plaque central axes were ≤2.5%, though larger differences (up to 12%) were found near the plaque lip. Overall, good agreement was found between ACE and MC dose calculations for a single I-125 seed and in front of the COMS plaques in water. More complex scenarios need to be investigated to determine how well ACE handles heterogeneous patient materials.

The Effect of Surface Parameters to the Performance of Reverse Engineering Process

Reverse engineering (RE) process is capable of producing CAD models from the existing part without the need of a blueprints or CAD drawing. One of the method to implement RE is via 3D scanning and the main goal is to produce CAD files that have the highest accuracy possible when compared to the actual parts. Any effort to improve the 3D scanning process should be encouraged because it will save a lot of time and expenses. As a result, this research tends to investigate the effects of surface parameters (Percentage of triangles and Grids resolution) to the performance of RE. Design of Experiments (DOE) method was used and the responses are measured in terms of File size and Error percentage. From the results, it is very interesting to note that the percentage of triangles does not have a significant effect to the file size but plays a major role in minimizing the dimension error. The grids resolution has the significant effects to the file size and error percentage. It can also be concluded that in order to get the best RE performance, the percentage of triangles and file size should be set to maximum. This will ensure that the generated CAD files will have the highest accuracy and from here, high quality products can be made from the RE process.

Arc-based additive manufacturing of steel components—comparison of wire- and powder-based variants

Additive manufacturing of components, layer-by-layer, offers several advantages compared to conventional production technologies such as higher material utilization efficiency and increased geometric possibilities. Arc-based additive manufacturing processes have the additional advantage of an almost unlimited assembly space, higher deposition rates, and an improved utilization factor of raw materials. Up to now, the gas metal arc welding variant, cold metal transfer (CMT), and other wire-based process combinations have been used predominantly in this field. Disadvantages of wire-based methods are the restricted availability of different types of wire consumables, the wire feed rate directly coupled to the heat input, and the lack of possibility to create multi-material structures with one heat source in-situ. Within this work, the 3D plasma-metal deposition (3DPMD) method, based on a plasma powder deposition process is introduced. 3DPMD has some advantages compared to the established plasma powder process and wire-based CMT process. Basis for this evaluation is the production of geometrically complex structures by the different methods (CMT & 3DPMD) and their subsequent characterization. Structures are fabricated using welding robots with the path control directly generated from the CAD files. In summary, 3DPMD offers increased flexibility in terms of material selection as well as the possibility to build graded structures. By using subroutines realized from a special postprocessor, it is possible to generate metal structures with standard welding robots directly from the CAD drawings. Microstructures and properties are directly related to the process and therefore material-process-property relationships are discussed within this work.

Reconstruction software of the silicon tracker of DAMPE mission

DAMPE is a satellite-borne experiment aimed to probe astroparticle physics in the GeV-TeV energy range. The Silicon tracker (STK) is one of the key components of DAMPE, which allows the reconstruction of trajectories (tracks) of detected particles. The non-negligible amount of material in the tracker poses a challenge to its reconstruction and alignment. In this paper we describe methods to address this challenge. We present the track reconstruction algorithm and give insight into the alignment algorithm. We also present our CAD-to-GDML converter, an in-house tool for implementing detector geometry in the software from the CAD drawings of the detector.

THE IMPORTANCE OF DIGITAL METHODS IN PRESERVATION OF CULTURAL HERITAGE THE EXAMPLE OF ZIRNIKLI MANSION

Abstract. Documentation in maintaining cultural properties is a highly important stage of work for determination of the unique properties. The researches having been carried out over years to increase the accuracy of documentation enabled it to reach such a point that the properties can be scanned by 3D laser scanners today. In order for the lost parts of the civil architecture examples required to be preserved in the context of cultural texture to be found and reconstructed, precise measurement have gained importance in documentation of the current status. Over years, major losses have arisen in the cultural texture situated around Erzurum Castle where the unique architectural examples are placed together. In this study, the importance of the 3D documentation in preserving the cultural properties is discussed in the context of Zırnıklı Vehbi Bey Mansion situated near to the Castle. The CAD drawings of this structure which has significantly lost its spatial integrity has been generated from the 3D laser point clouds, then the restitution and the restoration projects of the monument have been prepared accordingly.

Development of a cold wire-feed additive layer manufacturing system using shaped metal deposition method

Shaped metal deposition (SMD) method would be an alternative way to traditional manufacturing methods, especially for complex featured and large scale solid parts and it is particularly used for aerospace structural components, manufacturing and repairing of die/molds and middle-sized dense parts. This method is implemented by depositing continuous cold or hot-water melted via welding arc plasma heat. This paper presents the designing, constructing, and controlling of an additive manufacturing system using TIG plus wire based Shaped metal deposition (TW-SMD) method. The aim of the current study is to design and develop an integrated system which is able to reduce time consuming and boring task of deposition process. The developed additive system is capable of producing near net shaped components of sizes not exceed 400 mm in 3 directions directly from CAD drawing. The results showed that the developed system succeeded to produce near net geometries and error-free depositions for various features of SS308LSi components. Additionally, workshop tests have been conducted in order to verify the capability and reliability of the developed AM system.

Polyenergetic Known-Component Reconstruction without Prior Shape Models.

Previous work has demonstrated that structural models of surgical tools and implants can be integrated into model-based CT reconstruction to greatly reduce metal artifacts and improve image quality. This work extends a polyenergetic formulation of known-component reconstruction (Poly-KCR) by removing the requirement that a physical model (e.g. CAD drawing) be known a priori, permitting much more widespread application. We adopt a single-threshold segmentation technique with the help of morphological structuring elements to build a shape model of metal components in a patient scan based on initial filtered-backprojection (FBP) reconstruction. This shape model is used as an input to Poly-KCR, a formulation of known-component reconstruction that does not require a prior knowledge of beam quality or component material composition. An investigation of performance as a function of segmentation thresholds is performed in simulation studies, and qualitative comparisons to Poly-KCR with an a priori shape model are made using physical CBCT data of an implanted cadaver and in patient data from a prototype extremities scanner. We find that model-free Poly-KCR (MF-Poly-KCR) provides much better image quality compared to conventional reconstruction techniques (e.g. FBP). Moreover, the performance closely approximates that of Poly- KCR with an a prior shape model. In simulation studies, we find that imaging performance generally follows segmentation accuracy with slight under- or over-estimation based on the shape of the implant. In both simulation and physical data studies we find that the proposed approach can remove most of the blooming and streak artifacts around the component permitting visualization of the surrounding soft-tissues. This work shows that it is possible to perform known-component reconstruction without prior knowledge of the known component. In conjunction with the Poly-KCR technique that does not require knowledge of beam quality or material composition, very little needs to be known about the metal implant and system beforehand. These generalizations will allow more widespread application of KCR techniques in real patient studies where the information of surgical tools and implants is limited or not available.

Novel experimental technique for 3D investigation of high-speed cavitating diesel fuel flows by X-ray micro computed tomography.

An experimental technique for the estimation of the temporal-averaged vapour volume fraction within high-speed cavitating flow orifices is presented. The scientific instrument is designed to employ X-ray micro computed tomography (microCT) as a quantitative 3D measuring technique applied to custom designed, large-scale, orifice-type flow channels made from Polyether-ether-ketone (PEEK). The attenuation of the ionising electromagnetic radiation by the fluid under examination depends on its local density; the transmitted radiation through the cavitation volume is compared to the incident radiation, and combination of radiographies from sufficient number of angles leads to the reconstruction of attenuation coefficients versus the spatial position. This results to a 3D volume fraction distribution measurement of the developing multiphase flow. The experimental results obtained are compared against the high speed shadowgraph visualisation images obtained in an optically transparent nozzle with identical injection geometry; comparison between the temporal mean image and the microCT reconstruction shows excellent agreement. At the same time, the real 3D internal channel geometry (possibly eroded) has been measured and compared to the nominal manufacturing CAD drawing of the test nozzle.

The CAD drawing as a source of data for robot programming purposes – a review

Industrial robots are widely used in mass production, successfully replacing the workers during repetitive tasks. The lack of direct human participation in the production process involves the necessity of programming of the machines, which is mostly the time-consuming process. Most of the operations are well described in the process documentation, but some actions require the use of complicated paths, like for example welding, laser or water cutting, edge grinding, application of liquid sealants or films of paint etc. All of the mentioned activities need the precise movements of robot’s effector and this is - in many cases - connected with the necessity of entering of many points that approximate the path. One of the ways to solve this problem is the possibility of generating the complex path automatically, using the information from the technical documentation. This paper presents such approach that uses the CAD drawings as a data source. The available literature presents this problem mainly in the aspects of large software applications, but this paper was focused on presenting the problems of the proper analysis of the drawing and how to process the data to the form that can be used during robot programming.

University Library External Window Sunshade Device Simulation Analysis and Optimization Design

Influence of solar radiation for the library external shading devices were simulated and analyzed using the Weather Tool software library exterior environment analysis, the thermal comfort of the building with minimal impact of changes in the program is to take passive shading measures, the use of ecological building Ecotect simulation software to analyze the effects of the sun visor on the building indoor solar radiation, in the CAD drawing software based on the library modeling, climate data import, mesh through Ecotect, analyzed under different circumstances in the reading room of the sun visor change the radiation given control strategy corresponding visor adjustment, and on this basis, designed a foot shading device, and more convenient for students to use.

Reason Maintenance in Product Modelling via Open Source CAD System

The present and future challenges of a new product design, forecasting and risk management launch strategy for a new product modelling decision process. This paper intends to propose and to look towards the development of a low-cost integrated CAD-CAPP-CAD/CAM product modelling system for the design and manufacture of a proposed product. It is a mapping between several design phases like functional design, technical design and physical design. The modelling data generation process begins with the drafting of a product to be maintained using the drafting software package. From the CAD drawing, the data are transferred to be used as the product models and a CAPP software package will then prepare the operational parameters for the manufacturing of the product. These process data are relayed to a CAM software package, which will then generate the automating information-processing functions. The final stage of the function is to support design and manufacturing operations that may have reaped many benefits in terms of its initial equipment and software costs.

A study on scan data matching for reverse engineering of pipes in plant construction

The domestic plant construction market is in a prosperous condition, due to the uprising demand for industry facility and infrastructure, triggered by the oil price rise in Middle East Asia. It is difficult, however, to survive in competition with advanced foreign construction companies, because domestic companies rely heavily on labor-intensive construction conventions in AEC(Architectural, Engineering and Construction industry). In particular, the piping work in a plant construction project accounts for many portions of the critical paths, from the viewpoint of process control. Although plant construction projects need to deal with complex three-dimensional piping information, most domestic companies rely on two-dimensional CAD drawings for construction and quality control, which frequently leads to significant problems, such as construction delay, and productivity decrease. For such reasons, it is problematic, in that the build ability, workability, and productivity of projects are dependent on the workers' abilities to understand drawings and their technical skill. In other words, as plant construction projects are getting more complicated in details, and more increased in size, it is urgently needed to develop an efficient information management methodology, in order to figure out heterogeneous 3D piping information in a real-time manner. Reverse engineering for obtaining 3D shape information using a 3D laser scanner is used, in order to extract drawing information from constructed objects. In particular, as piping works control the Critical Path (CP) in the plant construction project, in this study, a reverse engineering algorithm is proposed, which can measure the preciseness of pipes, by comparing the 3D CAD model and the 3D shape information obtained from a laser scanner. Applying the algorithm can contribute to re-construction prevention and quality control in the construction process.

Development of a New Powder/Solid Composite for Biomimic Implant Materials by Electron-Beam Additive Manufacturing

We proposed a new biomaterial composed of solid and powder cubic compartments to exhibit isotropic or bone-mimic one-dimensional anisotropic mechanical properties. The raw material used was gas-atomized Ti-6Al-4V ELI powder comprising spherical particles with a diameter of approximately 80 μm. Cube-shaped products composed of 27 (3 × 3 × 3) unit cubic compartments occupied by solid or powder part were designed using three-dimensional CAD. The products were fabricated by electron beam melting (EBM) (Arcam AB, Sweden) according to the specifications shown in a CAD drawing. The residual unmelted powder in the products does not need to be removed to make the products more mechanically integrated. Moreover, the layout of the powder and solid compartments in the products were arranged to achieve isotropy resembling a face-centered cubic atomic arrangement or a long-bone-mimic mechanical anisotropy with square prismatic columns. The products demonstrate isotropic or anisotropic Young’s modulus, yield stress, and toughness, all of which can be changed by CAD design and EBM. In conclusion, novel powder/solid materials comprising solid cubic parts and functionalized powder particles between them were successfully developed, which could be useful in biomedical and industrial applications.

A unified framework for authenticating topology integrity of 2D heterogeneous engineering CAD drawings

This paper presents a novel unified framework for authenticating topology integrity of 2D heterogeneous engineering CAD drawings. Topology information, through which a variety of engineering reports are generated, plays the most important role in the engineering CAD field. However, topology integrity authentication for engineering CAD drawings is still in its infancy and few efforts were made in the literature. By efficiently extracting topological and geometric features regardless of their heterogeneity with respect to geometrical shape and topology representation, the proposed framework supports verifying topology integrity for various heterogeneous engineering CAD drawings, such as process flow diagrams (PFD), piping and instrument drawings (P&ID), piping isometric drawings (ISO) as well as sectional drawings. Topology authentication is achieved through embedding local topological features into geometric features by introducing a generic and effective semi-fragile watermarking scheme. A novel descriptor, called topology local binary patterns (T-LBP), is proposed to extract local topological features of heterogeneous drawings. Theoretical analysis and experiments have demonstrated the discrimination power, robustness and sensitivity of the proposed T-LBP descriptor. We also carry out further experiments to prove that the proposed framework can not only detect and locate malicious topological modifications, but also yield strong robustness against various topology preserving modifications.

Open-source, small-animal magnetic resonance-guided focused ultrasound system.

BackgroundMR-guided focused ultrasound or high-intensity focused ultrasound (MRgFUS/MRgHIFU) is a non-invasive therapeutic modality with many potential applications in areas such as cancer therapy, drug delivery, and blood-brain barrier opening. However, the large financial costs involved in developing preclinical MRgFUS systems represent a barrier to research groups interested in developing new techniques and applications. We aim to mitigate these challenges by detailing a validated, open-source preclinical MRgFUS system capable of delivering thermal and mechanical FUS in a quantifiable and repeatable manner under real-time MRI guidance.MethodsA hardware and software package was developed that includes closed-loop feedback controlled thermometry code and CAD drawings for a therapy table designed for a preclinical MRI scanner. For thermal treatments, the modular software uses a proportional integral derivative controller to maintain a precise focal temperature rise in the target given input from MR phase images obtained concurrently. The software computes the required voltage output and transmits it to a FUS transducer that is embedded in the delivery table within the magnet bore. The delivery table holds the FUS transducer, a small animal and its monitoring equipment, and a transmit/receive RF coil. The transducer is coupled to the animal via a water bath and is translatable in two dimensions from outside the magnet. The transducer is driven by a waveform generator and amplifier controlled by real-time software in Matlab. MR acoustic radiation force imaging is also implemented to confirm the position of the focus for mechanical and thermal treatments.ResultsThe system was validated in tissue-mimicking phantoms and in vivo during murine tumor hyperthermia treatments. Sonications were successfully controlled over a range of temperatures and thermal doses for up to 20 min with minimal temperature overshoot. MR thermometry was validated with an optical temperature probe, and focus visualization was achieved with acoustic radiation force imaging.ConclusionsWe developed an MRgFUS platform for small-animal treatments that robustly delivers accurate, precise, and controllable sonications over extended time periods. This system is an open source and could increase the availability of low-cost small-animal systems to interdisciplinary researchers seeking to develop new MRgFUS applications and technology.

Dimensional Arrow Detection from CAD Drawings

Objectives: This paper proposes an approach to effectively identify dimensional arrow heads from the CAD drawing images. Methods/Analysis: The proposed approach implements a multi-level thresholding and morphological operations in order to detect arrow like entity and some additional morphological steps in order to filter out non-arrow like entities from CAD drawing images. A histogram based multi-level thresholding is implemented. Morphological Black hat is used to detect solid arrow heads while morphological white hat is used to detect line arrow heads. Properties of arrow heads are used to filter out unwanted entities. Findings: CAD drawings contain arrows to depict dimensions of the models. In many situations, users do not have access to the CAD file for the drawing or do not have suitable software to visualize the CAD file. In such cases, an image of 2D drawing can be processed in automated or semi-automated way to extract dimensional relationships between entities. One step in such extraction is to detect dimensional arrow heads. The approach was tested on variety of images of CAD drawings with increasing difficulties with 96.655% success rate. The F1 score for each image was calculated and the cumulative average F1 score was found out to be 0.9596, precision rate is 95.95%, recall rate is 96.83% which suggests acceptable accuracy. Applications/Improvement: The proposed approach helps to detect dimensional arrow heads from CAD drawing images using image processing.

3D MODELLING AND INTERACTIVE WEB-BASED VISUALIZATION OF CULTURAL HERITAGE OBJECTS

Nowadays, there are rapid developments in the fields of photogrammetry, laser scanning, computer vision and robotics, together aiming to provide highly accurate 3D data that is useful for various applications. In recent years, various LiDAR and image-based techniques have been investigated for 3D modelling because of their opportunities for fast and accurate model generation. For cultural heritage preservation and the representation of objects that are important for tourism and their interactive visualization, 3D models are highly effective and intuitive for present-day users who have stringent requirements and high expectations. Depending on the complexity of the objects for the specific case, various technological methods can be applied. The selected objects in this particular research are located in Bulgaria – a country with thousands of years of history and cultural heritage dating back to ancient civilizations. \this motivates the preservation, visualisation and recreation of undoubtedly valuable historical and architectural objects and places, which has always been a serious challenge for specialists in the field of cultural heritage. &amp;lt;br&amp;gt;&amp;lt;br&amp;gt; In the present research, comparative analyses regarding principles and technological processes needed for 3D modelling and visualization are presented. The recent problems, efforts and developments in interactive representation of precious objects and places in Bulgaria are presented. Three technologies based on real projects are described: (1) image-based modelling using a non-metric hand-held camera; (2) 3D visualization based on spherical panoramic images; (3) and 3D geometric and photorealistic modelling based on architectural CAD drawings. Their suitability for web-based visualization are demonstrated and compared. Moreover the possibilities for integration with additional information such as interactive maps, satellite imagery, sound, video and specific information for the objects are described. This comparative study discusses the advantages and disadvantages of these three approaches and their integration in multiple domains, such as web-based 3D city modelling, tourism and architectural 3D visualization. It was concluded that image-based modelling and panoramic visualisation are simple, fast and effective techniques suitable for simultaneous virtual representation of many objects. However, additional measurements or CAD information will be beneficial for obtaining higher accuracy.

3D MODELLING AND INTERACTIVE WEB-BASED VISUALIZATION OF CULTURAL HERITAGE OBJECTS

Abstract. Nowadays, there are rapid developments in the fields of photogrammetry, laser scanning, computer vision and robotics, together aiming to provide highly accurate 3D data that is useful for various applications. In recent years, various LiDAR and image-based techniques have been investigated for 3D modelling because of their opportunities for fast and accurate model generation. For cultural heritage preservation and the representation of objects that are important for tourism and their interactive visualization, 3D models are highly effective and intuitive for present-day users who have stringent requirements and high expectations. Depending on the complexity of the objects for the specific case, various technological methods can be applied. The selected objects in this particular research are located in Bulgaria – a country with thousands of years of history and cultural heritage dating back to ancient civilizations. \\this motivates the preservation, visualisation and recreation of undoubtedly valuable historical and architectural objects and places, which has always been a serious challenge for specialists in the field of cultural heritage. In the present research, comparative analyses regarding principles and technological processes needed for 3D modelling and visualization are presented. The recent problems, efforts and developments in interactive representation of precious objects and places in Bulgaria are presented. Three technologies based on real projects are described: (1) image-based modelling using a non-metric hand-held camera; (2) 3D visualization based on spherical panoramic images; (3) and 3D geometric and photorealistic modelling based on architectural CAD drawings. Their suitability for web-based visualization are demonstrated and compared. Moreover the possibilities for integration with additional information such as interactive maps, satellite imagery, sound, video and specific information for the objects are described. This comparative study discusses the advantages and disadvantages of these three approaches and their integration in multiple domains, such as web-based 3D city modelling, tourism and architectural 3D visualization. It was concluded that image-based modelling and panoramic visualisation are simple, fast and effective techniques suitable for simultaneous virtual representation of many objects. However, additional measurements or CAD information will be beneficial for obtaining higher accuracy.