Kellie’s Castle Facade Recording Using Digital Close-range Photogrammetry

Abd. Manan Samad*1, Norazlini Hassan Sauri*1, Muhd Asyraf Hamdani#2 Ramli Adnan*1 and Anuar Ahmad@3

Pixelgrammetry & Al-Idrisi Research Group (Pi_ALiRG) Centre of Studies Surveying Science and Geomatics

Faculty of Architecture, Planning and Surveying

*1Universiti Teknologi MARA Malaysia, Shah Alam, SELANGOR #2Universiti Teknologi MARA, Sri Iskandar, PERAK

@3 Universiti Teknologi Malaysia, Skudai, JOHOR

Email: dr_abdmanansamad@ieee.org

Abstract - Various surveying techniques has been used in the mapping for engineering purposes. Mapping is an important element in Geomatic Engineering. Conventional technique for mapping includes surveying technique that consist of data acquisition work on site, plotting and calculating. This technique is tedious and time consuming. This study is aimed at studying and a comparing an alternative technique for mapping of the Kellies Castle building, namely digital close-range photogrammetry. The purpose of introducing close range photogrammetry technique in mapping is to increase efficiencies of estimation process as well the reliability of the results. Photogrammetry procedures were sets up to determine the map. Then, a simple verification test is done to verity the result using digital close-range photogrammetry. Comparison between digital close-range photogrammetry and conventional technique was made to prove that digital close-range photogrammetry capable to be used as one of the reliable techniques in non- topo mapping. Keywords - Digital close-range photogrammetry, spatial information, Façade recording.

I. INTRODUCTION One of the scopes of works in construction is mapping. It has been important part in the assessment of the particular site for the purpose of planning and costing. Conventional technique for mapping includes surveying techniques that consists of data acquisition work on site, plotting and calculating. This technique is tedious and time consuming. This study is aimed at studying and a comparing an alternative technique for map the Kellies Castle building, namely close-range photogrammetry. Comparison between close-range photogrammetry and conventional technique was made to prove that close-range photogrammetry can be used as on of the reliable techniques in mapping. This will help to reduce the time and incurred in the process of map the building at site. Conventional technique also uses at least three worker to operate and lots of instrument used. For software photogrammetry is used the PhotoModeler.

PhotoModeler is a program that helps extract measurement and map from photographs. By using a camera as an input device, PhotoModeler lets capture accurate detail in short time.

II. DIGITAL CLOSE-RANGE PHOTOGRAMMETRY When ground-based cameras are employed, the term terrestrial photogrammetry is used. This term has been historically applied to the system of surveying and mapping from photographs taken at ground station. Terrestrial photogrammetry can be further classified as close-range photogrammetry if the camera-object distance is in the range of 0.1m to 100m [11]. Digital Close-Range Photogrammetry is an accurate, cost effective technique of collecting measurements of real world objects and conditions directly from photographs. Photogrammetry utilizes digital images to obtain accurate measurements and geometric data of the object or area of interest, in order to provide spatial information for engineering design, spatial surveys or 3D modeling. Two basic camera types are employed in terrestrial Photogrammetry. The first type is the metric camera and second is the non-metric camera. The metric camera, as the name implies, is designed and calibrated specifically for photogrammetric measurements. It has a known and stable interior orientation and is usually a fixed-focus camera. The non-metric camera is represented by a variety of fairly high-quality hand-held cameras used by amateur and professional photographers in which the primary objective is a photograph of good pictorial quality. The non-metric cameras will not, in general, maintain a constant interior orientation because they are not fixed focus, nor are they constructed with the rigidity and robustness of the metric cameras. Non-metric camera do not contain fiducial marks, but are sometimes retrofitted with these marks in order to obtain reliable photogrammetric measurements, satisfactory technique have been recently developed for calibrating non-metric cameras. Today, non

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

978-1-4673-0961-5/12/$31.00 ©2012 IEEE 216

metric camera plays an important part in close-range photogrammetry [11]. Digital Close-Range Photogrammetry techniques allow converting images of an object into a mapping. Using a digital camera with known characteristic such as lens focal length, imager size and number of pixels, need a minimum of two pictures of an object. If can indicate the same three object points in the two images and can indicate a known dimension can determine other 3D points in the images. Digital Close-Range Photogrammetry is a very good tool if have limited access time to the object to be modelled. Images can be captured very quickly. The trade off is that it can take a lot of time to process the images. If the number of points required to create a useful model is large, it can be very tedious with photogrammetry The quality or accuracy of the map can be affected by several things. The quality of the camera lens and the resolution of the imager chip, the camera calibration, and the number of images taken are all important. The benefits of Digital Close-range Photogrammetry over other field procedures are: Increased accuracy; complete as-built information, reduced costs, reduced on-site time and effective for small and large projects.

III. DIGITAL CAMERA Camera is clearly an important part of any photogrammetric measurement system. There are different types of cameras based on how the images is captured and stored film cameras, digital cameras, video cameras and tethered digital and video camera. When choosing a camera, should consider with project requirements and budget. The most common choice is a digital Single Lens Reflex camera. Point and shoot digital cameras are common as well. PhotoModeler can also work with photos taken with unknown cameras, providing there is some known information about the research. Digital Single Lens Reflex is an even better choice if within budget. With a DSLR have more control over settings, get to choose the best lens usually a fixed, non-zoom, wide angle, and often have higher resolution. For the research choose the Canon 5D Mark II with Lens Tamron 25-75mm f 2.8 [2]. Canon 5D Mark II is high performance for high expectation. One of the most notable features of this lens is the good center sharpness it delivers, with decent center sharpness at f/2.8 and good center sharpness at f/4 [2]. The Tamron 28-75mm f/2.8 [1], the ens focal length range is obviously 28mm to 75mm. This covers the basic focal lengths desired in a normal general purpose zoom lens but might feel long to some 1.6x FOVCF users. A 24mm wide angle would be better common on many other zooms in this class but 75mm on the long end is a little nicer than the common 70mm max focal length

IV. KELLIE’S CASTLE

Today, the rediscovered mansion popularly known as Kellie's Castle still stands, having survived the ravages of time. For many years, Kellies Castle has been shrouded in mystery. Today it's nicely restored and easy to reach from Ipoh. Kellie's Castle is located in Batu Gajah, Perak. The castle is not as famous as the Taj Mahal in Agra, India but there are some similarities, both in architecture as in the story of its building. Kellies Castle is a great tourist attraction situated in Perak State [3, 12, 13]. The story about the castle is as impressive as the castle itself. A grand mansion with are six storey tower, wine cellar and stately columns. Moorish arches and walls embellished with Greco-Roman designs. There was to be a rooftop courtyard for parties and even an elevator, the first of its kind in the country. But the building was never to be completed. Work halted in December 1926 with the sudden demise of its owner, William Kellie-Smith. The estate on which it was situated was sold and the unfinished mansion soon surrendered itself once to the jungle.

Figure1: Canon 5D Mark II

Figure 3: The Kellie's Castle, Batu Gajah, Perak.

Figure 2: Lens Tamron 25-75mm f 2.8

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

217

VI. RESEARCH METHODOLOGY

A. Stage 1: In this stage, the selection of suitable technique that best fits according to the identified research solution. It is about the appropriate technology to be chosen, such as conventional surveying, GPS or Photogrammetry. Reconnaissance is an important step before starting the fieldworks. The Kellie castle heritage building has been chosen. All information about the building and site were collected and recorded for the proper fieldworks observation planning. During the reconnaissance, recognizing and locating the proposed control points were done. For the observation using total station reconnaissance were undertaken before any angle and distance were measured to locate suitable positions for traverse stations and to locate control survey mark.

B. Stage 2: This stage includes decision on selecting digital close-

range photogrammetry approach, cameras, total station and processing software. Planning is needed to ensure that research study can be carried out smoothly. The Canon 5D Mark 2 [2] is used in this research and need to be calibrated by using calibration grid. PhotoModeler is selected because it able to be use with photography taken from different types of camera [7]. PhotoModeler calibrator is able to determine focal length, principal point, pixel square ness and lens distortion, and stores this information for future use. Camera calibration is a method for accurately determining values for camera parameters [7]. Once a camera is calibrated, it can be use for providing accurate measurements.

C. Stage 3: Total Station was used in fieldwork observation of control point survey for control geo-referencing in PhotoModeler. Following table 1 shows the observation data by using Total Station.

Canon 5D Mark II was used in taking photographs of Kellie Castle. All important reference points (control) on the Kellie Castle building must appear in at least every three adjacent taken photographs. PhotoModeler require reference points marked in two or more photographs [7]. Photographs taken side by side contain many of same object features and reference points. Many points referenced across photographs are needed as it is required in PhotoModeler image processing. Photography guidelines are as follows:

a. Efford to get the angles between the shots as close to right angles (90 degrees) as possible,

b. Take at least three photographs, c. Efford to get all important reference points on at

least three photographs, d. Efford to get as much as possible the overlap

between adjacent photographs, e. Efford to get photographs from both above and

below the object, if possible, f. Take many photographs of the object but use at

most four at the start until we determine that we need others, and

g. Measure the distance between two clearly visible reference points.

Figure 5 shows captured photos of the Kellie Castle from certain camera positions.

Figure 4: Flow chart of research methodology

Table 1: Control Point Coordinate

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

218

Figure 6 shows the flowchart of the processing by using PhotoModeler to measure, map and model the Kellie Castle. Firstly, set up a new project of PhotoModeler to create a new measurement project [8]. PhotoModeler will save the measurement works in a project file and allowed to resume the works with saved project. The images used in processing are stored separately on the hard disc. Once the project is completed, PhotoModeler can export the project files in various formats. The camera characteristics will be defined in the camera wizard at the beginning of the project. The camera is used to convert the real worldview into a digital image. Next process is collection of the images, which are imported and used in the project. Therefore, during data acquisition phase those acquire a lot of images to avoid repeating the data acquisition process. Then marking is the process of creating and positioning an object on a photograph. Points, edges, and lines are marked for its position on image. Referencing is the key step to ensure objects can be process to yield 3D positions. Figure shows the referencing step to portray the same point that appears in different images. The 3D viewer will shows all the 3D objects in the project that have valid 3D locations. Objects that do not have 3D locations because they appear only one photograph or cannot be computed by some other algorithm will not appear in the 3D viewer. To make the model look nicer and complete, adding surfaces to surfaces menu that are 3D objects and will only appear in 3D viewer. Once the three dimensional model has been created by PhotoModeler, it can be saved and exported into another softwares. PhotoModeler capable to exports data into following 3D file formats; DXF, 3DS (3D Studio), OBJ (Wavefront), X (Microsoft DirectX), VRML 1 and 2 (Virtual Reality Modeling Language for the Web), IGES, and RAW (raw coordinate data). PhotoModeler can also export the 3D data in a model projected onto a plane in 2D.

III. RESULTS AND ANALYSIS A. Camera Calibration Digital cameras used in this study were calibrated before acquiring images in the study area. Table 2 shows a summary of the calibrated parameters for the cameras used in mapping.

Figure 5: The figure shows the photos captured for Kellies Castle building

Figure 6: Flow chart of processing process

Table 2: The summary of the calibrated parameters

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

219

B. Accuracy assessment The quality of the model is assessed by the residuals between the image coordinates marked on the images by the user and the image coordinates calculated using calibration of the cameras. Table 3 shows the RMS values of some points in the model which depicts the accuracy achieved in the project. Point is the point identification number for some points used during referencing, XYZ values are model coordinates calculated during processing and XYZ precision values shows the marking accuracy, and the last column, the RMS residual value in pixels, achieved in the project. As per the guidelines of the photomodeler, Photomodeler Pro 5 Help [9] for a good photogrammetric project, RMS residual value should be less than 5. C. Comparison between real image, 3D model and plan In this project also the compare of images Kellie Castle between the real image, 3D model and plan.

D. Control Points coordinate between total station point and PhotoModeler point In the Table 4 shows the coordinate of X, Y and Z coordinate value for total station and PhotoModeler. All of value base on the number 1 is the point where assigned the 30162.182, 90938.007, 16.493 value as the local coordinate system. Each point of the Kellies Castle has X, Y and Z coordinate after assigned the measured value on the filed.

Table 3: Accuracy assessment of some points in the model.

Table 4: 3D Results Coordinate of Total Station point and PhotoModeler point

Figure 7: Comparison between real image, 3D model and plan

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

220

E. Comparisan Control Points coordinate between total station point and PhotoModeler point Based on the Table 5, it shows the comparison between total station and PhotoModeler in term of the X, Y and Z coordinate after assigned the local coordinate at the selected point as 30162.182, 90938.007, 16.493 value. The difference values of X, Y and Z depend on observation in engineering survey and the skilled in the digitizing. If there are big mistakes or error in the observation and digitizing stage, it would be effect on the accuracy results.

IV. CONCLUSION For the conclusion, it is found that the digital close-range

photogammetric technique has capability become one of the standard accepted technologies for non-topographic mapping application. For this research study, the non-topographic object is Kellies Castle building at Batu Gajah, Perak. In the data collection stage, the camera calibrations required and done due to achieve high accuracy results. Based from the results define the parameter and distortion information of the camera. Field data acquisition phase was carried out with the observation using total station and captured the images of the scene and object of interests. The photographs captured with different angle and all the important point overlaped in photographs using the camera. The digital images are processed using PhotoModeler software. PhotoModeler is good in modeling and generated the position of cameras and objects. The images of the object façade were imported to the software. The outputs generated from PhotoModeler were camera and object coordinates in local reference coordinate system. The result demonstrates the use of photogrammetry in accurate 3D modeling and visualization. The precision obtained in the 3D models corresponds perfectly which is required for any further work like reconstruction etc. Due to the availability of digital cameras in the market at reasonable costs, photogrammetry offers the best alternative technique to any other CAD based techniques used. Overall of the project, the objective was achieved where the capability of PhotoModeler for 3D map can be produced using digital close-range phototgrammetric technique.

East Coordinate for Total Station and Photo Modeler

30158

30159

30160

30161

30162

30163

30164

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Point No

Met

res Total station

Photo Modeler

Figure 8: Graph of East coordinate for the Total Station and PhotoModeler.

North Coordinate For Total station And Photo Modeler

909009090590910909159092090925909309093590940909459095090955

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Point No

Nor

th C

oord

inat

e

Total Sation

Photo Modeler

Figure 9: Graph of North coordinate for the Total station and PhotoModeler.

Height Coordinate for total Station and Photo Modeler

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Point No

Met

res Total station

Phto Modeler

Figure 10: Graph of Height coordinate for the Total station and PhotoModeler.

Table 5: Comparison between Total Station and PhotoModeler Coordinate

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

221

ACKNOWLEDGEMENT Pixelgrammetry and Al-Idrisi Research Group

(Pi_ALiRG); UiTM Research and Management Institute (RMI-UiTM); Centre of Studies Surveying Science and Geomatics, Faculty of Architecture, Planning and Surveying, UiTM; Faculty of Electrical Engineering, UiTM and Department of Geomatics, Faculty of Geoinformation and Real Estate, UTM Skudai are greatly acknowledged.

REFERENCES [1] Bryan Carnathan. Tamron AF 28-75mm f/2.8 XR Di LD Lens

Review. http://www.the-digital-picture.com/Reviews/Tamron-28-75mm-F-2.8-XR-Di-Lens-Review.aspx, 12 April 2011

[2] Digital Photography: Canon 5D Mark II, 1998-2011. http://www.dpreview.com/reviews/canoneos5dmarkii/ , 17 April 2010. [3] Dolphin Diaries Travel{KPL 5430}. Kellies Castle.

http://www.journeymalaysia.com/MHIS_kellies.htm. 18 December 2010.

[4] Eos Systems Inc. PhotoModeler. http://www.photomodeler.com/, 17 April 2011. [5] Eos Systems Inc. PhotoModeler software.

http://www.photomodeler.com/products/photomodeler.htm, 12 April 2011

[6] Eos Systems Inc. PhotoModeler Tutorials. http://www.photomodeler.com/tutorial-vids/online- tutorials.htm, 12 April 2011 [7] Eos Systems Inc. PhotoModeler Tutorials: About cameras.

http://www.photomodeler.com/products/photomodeler/about_cameras.htm. 12 April 2011

[8] Eos Systems Inc. (2007) PhotoModeler User Guide, 1st Edition, LEAD Technologies Inc.

[9] LEAD Technologies Inc (2004). PhotoModeler Pro 5 Version 5.1.0. PhotoModeler Pro 5 Help, 1991-2004.

[10] Matthews, N and Noble, T. Close-range hand out http://www.blm.gov/nstc/prodserv/ST134/pdf/Handout3CloseRange. 12 April 2011.

[11] Moffitt, F. H (1980). Photogrammetry, Third Edition, New York.

[12] pulau- pangkor.com. Kellies Castle. http://www.pulau-pangkor.com/Kellies-Castle.html. 18

December 2010. [13] Perak.info. Kellies Castle.

http://www.perak.info/kinta/Kellie_Castle_Batu_Gajah. htm. 18 December 2010.

[14] Simple3D, Close-Range Photogrammetry, 1999-2006. http://www.simple3d.com/photogrammetry.html, 20 July 2010

[15] Spatial Resources. Fast, Accurate, Affordable 3D Modeling and As Built Designs. http://www.spatialresources.com/id6.html, 20 May 2010.

[16] Walford, A (2007). Photogrammetry. http://www.photogrammetry.com, 19 September 2010

[17] Wolf, P. R, (2004). Elements of Photogrammetry, Third Edition.

2012 IEEE 8th International Colloquium on Signal Processing and its Applications

222