Mustafa Turker

Building-based damage detection due to earthquake using the watershed segmentation of the post-event aerial images

This paper presents an approach for detecting the damaged buildings due to earthquake using the watershed segmentation of the post‐event aerial images. The approach utilizes the relationship between the buildings and their cast shadows. It is based on an idea that if a building is damaged, it will not produce shadows. The cast shadows of the buildings are detected through an immersion‐based watershed segmentation. The boundaries of the buildings are available and stored in a GIS as vector polygons. The vector‐building boundaries are used to match the shadow casting edges of the buildings with their corresponding shadows and to perform assessments on a building‐specific manner. For each building, a final decision on the damage condition is taken, based on the assessments carried out for that building only. The approach was implemented in Golcuk, one of the urban areas most strongly hit by the 1999 Izmit, Turkey earthquake. To implement the approach, a system called the Building‐Based Earthquake Damage Assessment System was developed in MATLAB. Of the 284 buildings processed and analysed, 229 were correctly labelled as damaged and undamaged, providing an overall accuracy of 80.63%.

Building extraction from high-resolution optical spaceborne images using the integration of support vector machine (SVM) classification, Hough transformation and perceptual grouping

Abstract This paper presents an integrated approach for the automatic extraction of rectangular- and circular-shape buildings from high-resolution optical spaceborne images using the integration of support vector machine (SVM) classification, Hough transformation and perceptual grouping. The building patches are detected from the image using the binary SVM classification. The generated normalized digital surface model (nDSM) and the normalized difference vegetation index (NDVI) are incorporated in the classification process as additional bands. After detecting the building patches, the building boundaries are extracted through sequential processing of edge detection, Hough transformation and perceptual grouping. Those areas that are classified as building are masked and further processing operations are performed on the masked areas only. The edges of the buildings are detected through an edge detection algorithm that generates a binary edge image of the building patches. These edges are then converted into vector form through Hough transform and the buildings are constructed by means of perceptual grouping. To validate the developed method, experiments were conducted on pan-sharpened and panchromatic Ikonos imagery, covering the selected test areas in Batikent district of Ankara, Turkey. For the test areas that contain industrial buildings, the average building detection percentage (BDP) and quality percentage (QP) values were computed to be 93.45% and 79.51%, respectively. For the test areas that contain residential rectangular-shape buildings, the average BDP and QP values were computed to be 95.34% and 79.05%, respectively. For the test areas that contain residential circular-shape buildings, the average BDP and QP values were found to be 78.74% and 66.81%, respectively.

Support vector machines classification for finding building patches from IKONOS imagery: the effect of additional bands

Abstract This study aims to find building patches from pan-sharpened IKONOS imagery using two-class support vector machines (SVM) classification. In addition to original bands of the image, the normalized digital surface model, normalized difference vegetation index, and several texture measures (mean, variance, homogeneity, contrast, dissimilarity, entropy, second moment, and correlation) are also used in the classification. The study illustrates the performance of the binary SVM classification in building detection from IKONOS imagery. Moreover, the effect of additional bands in building detection is examined. The approach was tested in three test sites that are located in the Batikent district of Ankara, Turkey. The SVM classification provided quite accurate results with the building detection percentage (BDP) values in the range 81.27–96.26% and the quality percentage (QP) values in the range 41.01–74.83%. It was found that the usage of additional bands in SVM classification had a significant effect in building detection accuracy. When compared to results obtained using solely the original bands, the additional bands increased the accuracy up to 10.44% and 8.45% for BDP and QP, respectively.

A model-based approach for automatic building database updating from high-resolution space imagery

This article presents an approach for automatic building database updating from high-resolution space imagery based on the support vector machine (SVM) classification and building models. The developed approach relies on an idea that the buildings are similar in shape within an urban block or a neighbourhood unit. First, the building patches are detected through classification of the pan-sharpened high-resolution space imagery along with the normalized digital surface model (nDSM) and the normalized difference vegetation index (NDVI) using the binary SVM classifier. Then, the buildings that exist in the vector database but not seen in the image are detected through the analyses of the detected building patches. The buildings, which were constructed after the compilation date of the existing vector database, are extracted through the proposed model-based approach that utilizes the existing building database as a building model library. The approach was implemented in selected urban areas of the Batikent district of Ankara, the capital city of Turkey, using the IKONOS images and the existing building database. The results validated the success of the developed approach, with the building extraction accuracy computed to be higher than 80%.

An improved cluster-based snake model for automatic agricultural field boundary extraction from high spatial resolution imagery

ABSTRACT Agricultural field boundary information is important and often required for the geosciences and the agricultural sector. In this paper, a novel method is developed to extract sub-boundaries within the permanent boundaries of agricultural land parcels from high-resolution optical satellite imagery using an improved cluster-based snake model. The method takes the advantage of the results of an automatic fuzzy c-means (FCM) clustering and edge detection to compute external forces for an improved gradient vector flow (GVF) snake model. The GVF snake algorithm is improved by using an automatic seeding model based on clustering results and image moment functions. To seed the improved GVF algorithm, an ellipse is automatically delineated for each cluster within agricultural parcel by utilizing image moment functions (in particular silhouette moments). The GVF snake model is then implemented for each seed, one seed at a time. Active contours tend to have curve shapes rather than straight lines due to their structure that consists of several connected nodes within each contour. Therefore, the final accurate results are obtained after performing a three-stage line simplification operation. The experiments of the method were conducted on 20 test fields in a study area located near to the town of Karacabey, Turkey, using the 4-m resolution IKONOS multispectral (xs) image, the 2.44-m resolution QuickBird xs image, and the 0.61-m resolution QuickBird pan-sharpened (PS) image. Experimental results demonstrate that using both the clustering and edge detection results as external forces for the improved GVF snake model increases the accuracy of the results. In addition, the developed method showed a fairly good performance in extracting sub-boundaries for the fields comprising crops with an inherent high inner heterogeneity, such as rice and corn. The method can potentially be applied in the extraction of within-field sub-boundaries from high-resolution satellite imagery in agricultural areas.

EYE MOVEMENT CONTROLLED PERIPHERALS FOR THE HANDICAPPED-PARALYZED PEOPLE AND ALS PATIENTS

Controlling some devices in their daily life for the handicapped-paralyzed people and ALS (Amyotrophic Lateral Sclerosis) patients is an important challenge. In this study, a wearable system, called SmartEyes, is developed. The system is controlled by the eye movements of the user. With the help of this system, two groups of facilities are provided. The first is: communicating with predefined voiced messages, valuable especially for people who are unable to talk, and the second is: controlling some peripherals which are in the range around the user. The novelty of the developed system is that it navigates among the menus by means of the eye movements with the help of synthesized voice messages and without a need to sit across a monitor. In the control part, both the infrared (IR) and radio frequency (RF) wireless technologies were employed. The details of the peripheral control operations, namely: controlling the desk light, rolling curtain, TV, air conditioner and the sickbed, are explained in detail. The test results show that the system works quite satisfactorily in tracing and implementing the commands given by the user’s pupil gaze directions. We found that the overall satisfaction is quite high by yielding a total average survey score of 4.7 out of 5. We believe that the developed system offers a practical and efficient solution for making the lives of handicapped-paralyzed people and ALS patients easier. We carry on improving the skills of our SmartEyes system.

Automatic near-photorealistic 3-D modelling and texture mapping for rectilinear buildings

Abstract Three-dimensional (3-D) representations of urban regions have gained much attention because of recent developments in remote sensing and computer graphics technologies. In particular, textured 3-D building reconstruction for a variety of applications has been a popular research topic in recent years. In this study, we present the reconstruction of 3-D building models along with texture selection and mapping. Extracted two-dimensional building patches and normalized digital surface model (nDSM) data are used to generate the 3-D models. To build near-photorealistic 3-D models, the acquired geo-referenced facade textures are associated with the corresponding building facades using an automated GPS-assisted approach. On the other hand, the modelling and texture mapping of the roof structures were carried out manually. The study area is composed of eight housing estates (blocks), where a total of 110 buildings were analysed. The whole study area was modelled, with facade textures, in less than 1 min of processor running time with an acceptable level of accuracy. The texture mapping was carried out using MATLAB’s Virtual Reality Toolbox™.

An automatic region growing based approach to extract facade textures from single ground-level building images

An approach is presented for the automatic retrieval of building facade textures from single ground-level building images. The texture information is extracted using the Watershed segmentation which is carried out repetitively until the most successful segment is obtained. To initiate segmentation, the marker pixels are seeded automatically both for foreground (facade) and background (sky, pavement and neighboring build-ings) regions. The proposed concept was tested on two different datasets. The first dataset contains fifteen rectilinear buildings selected from the residential area of the Batikent district of Ankara, Turkey. The second dataset includes five buildings selected from the eTRIMS database, which contains over one hundred build-ings captured in major European cities. The assessment of the segmented facade images was carried out us-ing a quantitative evaluation metric. For both datasets, a quantitative accuracy of above 80% was achieved for facade texture extraction in average. The experimental results indicate that the proposed approach for the automatic retrieval of the facade textures is quite promising and a considerable progress has been made towards the automated construction of the virtual cities.