APPLICATION OF MODERN METHODS OF PHOTOGRAMMETRY AND SOFTWARE PACKAGES IN TEACHING Olivera Nikolić1, Petar Pejić2, Sonja Krasić3, Vladan Nikolić4 Abstract Teaching the subject of Descriptive geometry 3, at the Chair of Visual communications at the Faculty of Civil Engineering and Architecture of Nis, Serbia, was improved in 2011, by using contemporary software packages. This paper will present the presentation and application procedures of the restitution method in education of students, using widely present software for 3D modeling - SketchUp and the program for calibration of photographs - Tgi 3D. In case of the previously existing procedures of studying the restitution and photogrammetry model, the acquired knowledge of the students remained theoretical. By way of the introduced changes, the acquired knowledge found the application in practice through modeling of real structures in the city of Nis, and in their publication on the global Google Earth service. In this way the students contribute to the improvement of tourist presentation of Niš and Serbia on the web service, and thus contribute to the development of the community. The results of the introduced changes are reflected in the increased number of students opting for this course and the number of modeled and presented structures. Key words Descriptive geometry, improving education, modelling, photogrammetry methods, software.
To cite this paper: O. Nikolić, P. Pejić, S. Krasić, V. Nikolić. Application of Modern Methods of Photogrammetry and Software Packages in Teaching, In Proceedings of International Scientific Conference People, Buildings and Environment 2012, Vol .2, pp. 799-804, ISSN: 1805-6784.
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Olivera Nikolić, PhD student, Faculty of Civil Enginering and Architecture, Aleksandra Medvedeva 14, Nis, Serbia,
[email protected] 2 Petar Pejić, PhD student, Faculty of Civil Enginering and Architecture, Aleksandra Medvedeva 14, Nis, Serbia,
[email protected] 3 Sonja Krasić, docent dr, Faculty of Civil Enginering and Architecture, Aleksandra Medvedeva 14, Nis, Serbia,
[email protected] 4 Vladan Nikolić, PhD student, Faculty of Civil Enginering and Architecture, Aleksandra Medvedeva 14, Nis, Serbia,
[email protected] 799
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INTRODUCTION
Through the curriculum of the subject Descriptive geometry 3, of the Chair of visual communications at the Faculty of Civil Engineering and Architecture of Nis, the students of the second year of Bachelor studies of architecture study the methods of restitution and photogrammetry, which are the processes inverse to the perspective image drawing. [1] With the development of 3D presentations of structures on the Google Earth service, 3D maps of the places are created, facilitating movement and learning about various locations on the planet. The process of recovering 3Dstructure from2Dimages has been a central endeavor within computer vision, and the process of rendering such recovered structures is an emerging topic in computer graphics. [2] The models of the structures placed on Google Earth have been designed in SketchUp software applying restitution and photogrammetry method, using a minimum of two photographs of the structure, taken from opposite angles. The development of 3D maps was the reason for introducing the innovations in the curriculum of the Descriptive geometry 3 course, as it was concluded that by introducing the software to the teaching process and by educating the students to use it, production of a threedimensional presentation of Nis, but also other towns in the region, taking into consideration the more than 70% of the students at the Faculty of Civil Engineering of Nis comes from other places in Serbia, could be initiated. 2
THE PREVIOUS WORKING METHOD
Through a training lasting one semester, using the traditional drawing method, the students solved three tasks with the preset layouts where the perspective drawing of the structure with one known dimension was given. Applying the restitution method, comprising firstly finding the vanishing point, horizon line, principal point and distant point, and then determination of dimensions, size and shape of the structure according to which the orthogonal projections of the structure, the layout and views are drawn, the students mastered the procedures of obtaining the dimensions and forms of the structure on the basis of the photograph or perspective drawing of the structure. The knowledge acquired at the subject is widely applicable in architectonic practice. These methods can provide necessary data about dimensions, shape, views of the existing structures, all on the basis of the photographs of spatial structures. In this way it is possible to produce the design documentation of the building heritage structures, for which there are no plans and documents, or to restitute the contemporary structures whose data are not available. [3] Apart from the wide application, the acquired knowledge of the students remained theoretical, as in their further work, they rarely drew in a classic way, using paper, ruler and pencil. 3
INTRODUCED INNOVATIONS IN EDUCATION
As in the contemporary architectonic practice, the 3D presentation of the structures is achieved by usage of software, thus the software is also used for restitution process.
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Photogrammetry is progressively becoming the best technique to use for the metric survey of architectural objects. [4] For years, the restitution method is performed using CAD software, and the photogrammetry method using Google SketchUp. The new curriculum was thus devised, so that the students have two hours of practice a week and thirteen weeks in a semester, to create a model of an existing structure in the city and place it on the 3D Warehouse service, from where it is transmitted to Google Earth, through the activities presented in Table 1. In the first weeks, at the beginning of the construction of models, the students get acquainted with the techniques of photographing the structure and choose the best perspective. The following two weeks, they master the ways to process the photographs in Photoshop, which comprises removal of superficial details from the environment (greenery, people, advertisements…) which in some way interfere with the display of facades. The following three weeks, the students are instructed how the Tgi3D Photoscan software operates, and which is used for calibration of chosen photographs and finding characteristic points on the structure. The following five weeks, the students model the structure in SketchUp, and paste the textures taken from the photographs of the existing structure, and bringing down the structure to the scale 1:1 according to the photograph of the fifth façade of the structure on Google Earth. The last week is intended for placing the structure on 3D Warehouse service, from which, after authorization the object is automatically set on Google Earth. Tab. 1)
New curriculum and activity No.
Activity
Duration (week)
1.
Taking photographs of the structure in the field
2
2.
Processing the photographs in Photoshop
2
3.
Calibration of photographs in TGI software
3
4.
Production of models in SketchUp
5
5.
Lacing the structure on 3D Warehouse service
1
The model production process according to the mentioned activities will be presented on the example of modeling the temple of St. Emperor Constantine and Empress Helena. 3.1
Photogrammetry of the temple of St. Emperor Constantine and Empress Helena in Nis
In order to present an example of photogrammetry in this paper, the temple of St. Emperor Constantine and Empress Helеna in Nis was chosen. As the structure is symmetrical, 3 photographs including one half of the structure were chosen (Fig 1). [5]
Fig. 1)
Photographs of the temple of st. Emperor Constantine and Empress Helena in Nis
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3.1.1 Calibration Calibration of selected images was performed in the software package “Tgi3D SU PhotoScan Calibration Tool”, by entering the characteristics of the camera that took them and by calibration of the common points visible in all photographs. (Fig 2a). The photographs adjusted in this manner were exported in *.skp format for the purpose of further drawing of the model. 3.1.2 Production of 3D model SketchUp software was used for production of the 3D model on the basis of the previously calibrated photographs. By importing the file exported from the Tgi3D and by adjustment of the origin of coordinate system, the conditions for the start of modeling were created (Fig 2b).
Fig. 2)
a) calibration of the photographs
b) production of three-dimensional model
A model of the Temple in an unknown scale was obtained. In order to scale the model, we needed knowledge of the distance of any two points on the structure. Finding of actual dimensions employed the web service Google Maps, with which the software package SketchUp is directly linked, and can take down a part of the terrain as a town planning map in actual size. The scaling was done in respect to the fifth façade of the structure, and it was scaled 1:1. Apart from the actual size of the structure, by using the web service Google Maps, the precise global position and orientation of the structure were obtained. The structure positioned in this way can be, with the aid of Google Earth (Fig 3) service rendered globally accessible to everyone, and give a new, third dimension to 2D presentations of structures.
Fig. 3)
web presentation of the model
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ACHIEVED RESULTS
At the time when the changes in teaching process were taking place, there were only several buildings in Nis on Google Earth. In the winter semester 2011/12, the test project transformation in teaching with the group of 12 students was conducted and 12 models of the existing structures chosen by the students, at various locations in the city were obtained. At the beginning of 2012 the students who completed training, in cooperation with the employees of the Chair, applied with a project "3Dimensional presentation of Nis" for the Program for partnership and development of community, financed by the company „Philip Morris“. The project relates to modeling and presentation on Google Earth, of the structures of central city Obrenoviceva street, urban entity „Sokace“ and fifty historical and cultural monuments, and it will be realized by the end of April 2013. Around 200 buildings will be modeled through this project. In the next semester, the new generation of students, 24 of them at the subject Descriptive geometry 3 and 24 of them on the course Modeling in architecture and town planning, will adopt methods of restitution and photogrammetry according to the successfully changed program. By presenting Niš on Google Earth, the students contribute to the community and improve the tourist presentation, which is very important for the city approaching the central celebration of 1700 years since the signing of the Edict of Milan and adoption of Christianity, which will be held in Nis in 2013. 5
CONCLUSION
Computer assisted methods are more and more developed in education and new technologies are used enthusiastically by students. Different approaches as well as techniques are available: educational course information system, e-mail, electronic lecture materials in Internet or on CD/diskette, computer assisted lecturing, computer assisted exercises and distance learning. [6] The conducted reforms in the curriculum of the subject Descriptive geometry 3 and the achieved results are a positive example of transformations which must occur in the majority of other subjects at the Faculty of Civil Engineering in Nis, and which are not the designing subjects. The knowledge acquired by the students at the Faculty, in various areas, must be practically applicable. This means that it is necessary to observe and research the needs of contemporary society, and implement the found solutions in the teaching program. It is also very important to use software and software additions which do not have wide field of application. On the chair for visual communications, this process began in 2008, and the majority of courses became very popular with the students in the meantime. The elective subjects such as Modeling in architecture and town planning, Geometrical surfaces in architecture, Descriptive geometry 3 are elected by 95% of students of architecture which proves the success of the introduced changes. REFERENCES [1] Pejić, P., Petrić, E., Krasić, S. Restitution and Photogrammetry as a method of creating threedimensional architectural models, Proceedings of International conference "Innovation as a Function of Engineering Development" IDE 2011, Niš, November 25th and 27th , Niš: Faculty of Civil Engineering and Architecture, 2011, pp. 283-288.
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[2] Debevec, P. Ph.D. Thesis: Modeling and rendering architecture from photographs, Berkeley , University of California at Berkeley , 1996, pp. 4-3. [3] Paquet, E., Beraldin, J. A., Viktor, H. L., Benedetti, B., The application of content-based indexing and retrieval of digital pictures and range images to the 3D virtual reconstruction of complex sites and architectures, Volume XXXVI-5/W47, 2007, ISPRS Workshop 3D-ARCH 2007: "Virtual Reconstruction and Visualization of Complex Architectures", 12-13 July 2007. ETH Zurich, Switzerland, 2007, CD ROM, pp. 10. [4] Menci, L., Rinaudo, F. New trends in digital photogrammetry teaching and diffusion: The Z-glif software, Proceedings of XXI International CIPA Symposium 2007, 01-06 October2007., Athens, Greece, 2007. 4 pp. [5] Pejić, P., Krasić, S., Nikolić, O. Creation of architectonic 3d models by contemporary photogrammetry methods, Proceedings of 3rd International Scientific Conference moNGeometria 2012, Novi Sad, June 21th and 24th , Novi Sad: Faculty of Technical Sciences Novi Sad, 2012, pp. 289-296. [6] Grussenmeyer, P., Drap, P., Teaching Architectural Photogrammetry on the Web with ARPENTEUR. XIXth Congress of the International Society for Photogrammetry and Remote Sensing (ISPRS), Geoinformation for all, Amsterdam 16-23 July 2000. Int. Archives of Photogrammetry and Remote Sensing, Vol. XXXIII, part 6, GITC, Amsterdam, Netherlands, 2000. pp. 102-109.
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