Umut Gunes Sefercik

Gebze Technical University | GYTE · Geomatics Engineering

Ayçiçeği, dünyanın farklı bölgelerinde yaygın olarak yetiştirilen besin, ekonomik ve tıbbi değeri yüksek olan önemli bir tarımsal üründür. Ülkemiz için de önemli yağlı tohum kaynaklarından biri olan ayçiçeğinin tespiti ve izlenmesi yüksek doğrulukta verim tahminlemesi ve sürdürülebilir üretim planlaması açısından büyük önem arz etmektedir. İnsansız...

The recent developments have prompted the adoption of diverse methods and technologies in the generation of geospatial information. Furthermore, the growing interest in the digital twin concept and the demand for more realistic three-dimensional (3D) models of objects have contributed to an increased familiarity with 3D modeling research. In this c...

In order to meet the demands of rapid population growth and economic development, coastal cities are undertaking land reclamation projects with the objective of constructing new airport areas. Nevertheless, it is important to note that subsidence can occur as a result of this process. Therefore, monitoring ground deformation in reclaimed airports i...

The earthquakes with magnitudes of 7.8 and 7.6 that occurred in the Pazarcık and Elbistan districts of Kahramanmaraş province on February 6, 2023, respectively, have once again revealed Türkiye's earthquake reality. The earthquakes affected a very wide area covering 11 provinces and caused very heavy financial and emotional losses. In earthquakes t...

Recently, the use of unmanned aerial vehicles (UAVs) in bathymetric applications has become very popular due to the rapid and periodic acquisition of high spatial resolution data that provide detailed modeling of shallow water body depths and obtaining geospatial information. In UAV-based bathymetry, the sensor characteristics, imaging geometries,...

Unmanned aerial vehicle (UAV) technology is capable of delivering high spatial, spectral, and temporal resolution data that facilitate the monitoring of crops over time and provide crucial timely and quantifiable information about the yield, growth, and health of crops. Accurate identification of sunflower crops from UAV orthomosaics is essential f...

The increasing demand for digital agriculture necessitates agricultural productivity and environmental sustainability advancements. Unmanned Aerial Vehicle (UAV)-based remote sensing technologies offer valuable insights for enhancing crop yields and optimizing resource use compared to traditional ground-based data collection methods. Processing the...

The numerous advantages such as high geometric and radiometric accuracy and low cost provided UAV as a highly demanded alternative technology for mapping purposes. Integration of multispectral (MS) cameras and RTK positioning capabilities are two of the main factors that arise the preference of UAVs. The quality of the UAV products firstly depends...

The utilization of remote sensing products for vehicle detection through deep learning has gained immense popularity, especially due to the advancement of unmanned aerial vehicles (UAVs). UAVs offer millimeter-level spatial resolution at low flight altitudes, which surpasses traditional airborne platforms. Detecting vehicles from very high-resoluti...

The requirement of land use and land cover (LULC) maps as a base in large variety of applications make necessary to improve low-cost and high accuracy production methods. Unmanned Aerial Vehicles (UAVs) present cost-effective alternatives for generating LULC maps when compared to traditional methods and stand out with advanced multispectral sensing...

Modern remote sensing technologies play a critical role in agricultural applications, especially in recent years with the advances in unmanned aerial vehicle (UAV) technologies and artificial intelligence. Remotely sensed imagery is an invaluable data source for sustainable agricultural activities, such as precision agriculture. This study evaluate...

In spring 2021, mucilage, also known as “sea snot” or “sea saliva” has been intensely observed in the Sea of Marmara and has reached a threatening level. Due to the declining water quality, many marine organisms have perished, the fishing industry and tourism have been adversely affected. In this paper, a detailed investigation was carried out to a...

Powerlines are utilized for distributing electricity for household use, industry, healthcare purposes and etc. The detection of powerlines is an important topic in object detection studies. In addition, overgrown trees in dense forest regions may pose a risk for powerlines positioned in these regions and even may cause forest fires if unattended. S...

The concept of digital twin is included in many working disciplines today and its popularity is constantly increasing. There are photogrammetry-based mathematical models belonging to the geomatics discipline in the production of digital twin and three-dimensional (3D) model production can be easily realized with current advanced remote sensing tech...

Lately, unmanned aerial vehicle (UAV) become a prominent technology in remote sensing studies with the advantage of high-resolution, low-cost, rapidly and periodically achievable three-dimensional (3D) data. UAV enables data capturing in different flight altitudes, imaging geometries, and viewing angles which make detailed monitoring and modelling...

Lately, unmanned aerial vehicles (UAV) evolve into one of the most popular remote sensing technologies by providing rapid and periodical acquisition of high-resolution, accurate, and low-cost aerial data. Progressively, the technology of the UAVs rises with the addition of advanced equipment such as multispectral (MS) digital cameras and global nav...

In recent years, detailed monitoring of different vegetation classes by using modern remote sensing technologies has become one of the essential issues for smart agriculture activities. In this study, using three advanced machine learning algorithms, namely canonical correlation forest (CCF), rotation forest (RotFor) and support vector machines (SV...

Computer graphics have become highly advanced with the ability to offer users to experience a synthetic world and interact with the digital environment in a realistic manner. Within this concept, game engines are prominent tools for the visualization of three-dimensional (3D) geospatial data and for creating virtual reality (VR) based applications....

Ağaç sayımı, ürün gelişim takibi ve verim tahmini gibi birçok tarımsal uygulama için önemli veri kaynağı durumunda olan uzaktan algılama teknolojileri özellikle son yıllarda insansız hava aracı (İHA) teknolojileri ve yapay zeka alanındaki ilerlemeler ile birlikte hassas tarım uygulamalarında önemli bir rol oynamaktadır. Bu çalışmada, yüksek çözünür...

Kullanıcıların bir bilgisayar aracılığı ile kendilerini sanal bir ortamda deneyimlemesini sağlayan sanal gerçeklik (VR) teknolojisi ve sanal objelerin gerçeklik üzerine yerleştirilmesi ile yarı sanal bir ortam sunan arttırılmış gerçeklik (AR) teknolojisi üzerine yapılan çalışmalar uzun yıllardır gerçekleştirilmektedir. Fakat son yıllarda yaşanan te...

Dijital ikiz, haritacılık teknolojileri kullanılarak bir objenin aslına uygun şekilde üretilmiş üç boyutlu (3B) dijital kopyasıdır. Bu kavram, hayatımıza 21. yüzyıl başında yersel lazer tarama ve yersel fotogrametri gibi haritalama tekniklerinden elde edilen verilerin 3B işlenmesi ile girmiş ancak bu tekniklerin uygulanmasında yoğun saha çalışması...

The rapid increase in urbanization and industrialization has brought about a boosting effect in environmental pollution, causing a decrease in biological diversity and a deterioration in the ecological balance. As a result, the number of environmental disasters drastically increases every year. One of the most significant of these disasters is rece...

Poplars (Populus sp.), a member of fast-growing and short-lived tree species, have been widely planted since ancient times. Identification and mapping of poplar planted areas on global and local scales, as well as the automatic crown detection and counting of individual poplar trees in a given area provide valuable information to decision-makers in...

Unmanned aerial vehicle (UAV) systems have become frequently utilized in scientific studies in recent years, thanks to many advantages of low flight altitude. An important factor in the popularity of UAV systems is that high-resolution data can be obtained periodically, at a lower cost than traditional airborne remote sensing methods, in study area...

The quality of the final products produced with unmanned aerial vehicle (UAV) photogrammetry is increasing day by day; along with this, the process steps in the photogrammetric process are detailed, and work on quality improvement of products continues. Camera optimization is an important step in the processing of images in digital photogrammetry....

Kentleşme ve sanayileşmedeki hızlı artış, çevre kirliliğini artırıcı bir etki yaratarak biyolojik çeşitliliğin azalmasına ve ekolojik dengenin bozulmasına neden olmaktadır. Buna bağlı olarak, çevre felaketlerinin sayısı her yıl önemli ölçüde artmaktadır. Bu afetlerin en önemlilerinden biri, Türkiye'nin Marmara Denizi'nde yakın zamanda meydana gelen...

Marine mucilage that threatens marine habitats is one of the natural disasters, mainly resulting from global warming and marine pollution. Monitoring sea surface mucilage formations and mapping their spatial distributions provide valuable information to the local authorities and decision-makers in developing prevention and rehabilitation strategies...

Automatic vehicle detection from unmanned aerial vehicles (UAVs) is an important task in the remote sensing domain and plays a pivotal role in many applications such as traffic monitoring, parking lot management, search and rescue tasks. Inspired by the success of the deep learning paradigm in image processing applications, many object detection, a...

In the last decades, developments in game engine technology led to a raised attraction to the virtual reality (VR) and augmented reality (AR) concepts which offer users an interactive synthetic environment. Also, with the travel limitations of the current COVID-19 pandemic, VR tour applications that visualize the geospatial data gained popularity m...

İnsansız hava aracı (İHA) teknolojisi sonuç ürünlerinin en doğru geometride elde edilebilmesi ve ileri üretimlerde kullanılabilmesi için fotogrametrik işlem adımlarında pek çok parametrenin ve standartın doğru uygulanması gerekmektedir. Bu standartların başında gelenlerden biri de görüntü alımı yapan kameraların optimizasyonudur. İHA fotogrametrisi...

İnsansız hava aracı (İHA) sistemleri düşük uçuş irtifasının getirisi olan birçok avantaj sayesinde son yıllarda bilimsel çalışmalarda sıklıkla kullanılır hale gelmiştir. İHA sistemlerinin popüler hale gelmesinde, uygulanabilir genişlikte çalışma alanlarında, yüksek çözünürlüklü verinin geleneksel hava kaynaklı uzaktan algılama yöntemlerine nazaran...

In the last decades, unmanned aerial vehicles (UAV) became one of the most demanded remote sensing technologies with the advantage of rapidly and periodically achievable low cost, high resolution, and highly accurate data. Day by day, the technological level of UAVs is improved by the integration of novel instruments. Major novel instruments are mu...

The automatic detection and counting of trees are crucial for yield estimations, agricultural planning and forestry applications. Unmanned aerial vehicles (UAVs) and computer vision are increasingly used together for automatic image analysis since they can overcome time-consuming applications in a more precise, effective, and less error-prone manne...

In this study, YOLOv4 a state-of-the-art deep learning-based object detection method, was employed to extract stone pine trees from the UAV images acquired over the Gebze Technical University campus in Turkey.

Climate change and global warming along with human activities have caused abrupt changes in the atmosphere, marine, and terrestrial ecosystems. One of these changes is the rising number of mucilage events in marine ecosystems. During the recent two decades, mucilage blooms have begun to appear more frequently in the Sea of Marmara in Turkey, surrou...

Lately, improvements in game engines have increased the interest in virtual reality (VR) technologies, that engages users with an artificial environment, and have led to the adoption of VR systems to display geospatial data. Because of the ongoing COVID-19 pandemic, and thus the necessity to stay at home, VR tours became very popular. In this paper...

Unmanned air vehicle (UAV) became an alternative airborne remote sensing technique, due to providing very high resolution and low cost spatial data and short processing time. Particularly, optical UAVs are frequently utilized in various applications such as mapping, agriculture, and forestry. Especially for precise agriculture purposes, the UAVs we...

In recent years, there has been a significant increase in wildfires (forest fires) both in frequency and size around the world. Wildfires occurring by natural or anthropogenic reasons are disasters that seriously threaten the nature and its living ecosystem. The development of well-designed early warning, detection, monitoring and response strategi...

Physical reality is a concept in which humanity has deep knowledge and is in constant interaction. Through continuous connection with the physical environment humans learn to foresee features of the physical world and outcomes of certain events, however, digital computers, offering users a look into a “mathematical wonderland”, are used in order to...

In the last decades, the unmanned aerial vehicle (UAV) has become one of the most demanded remote sensing techniques with the advantage of very high resolution and accurate data derived from low flight altitudes. Due to increased demand in various applications, the technological level of UAVs is developing day by day. For accurate orientation of th...

Orman envanterinde önemli bir parametre olan meşcere yükseklik bilgisi, az gelişmiş ya da Türkiye gibi gelişmekte olan ülkelerde halen yaygın şekilde yersel tekniklerle tekil ağaç bilgisi edinme ve hata payı oldukça yüksek kestirimler ile bu bilgiyi genele yayma prensibi ile elde edilmektedir. Uzaktan algılama (UA) temelli modern ölçüm teknolojiler...

Unmanned air vehicle (UAV) has become an indispensable mobile mapping technology of remote sensing thanks to offering low cost and high resolution spatial data. Particularly, camera equipped optical UAVs are large in demand by land-related professions, including mapping, agriculture and forestry. Regarding the requirements, the technological level...

In recent years, with the remarkable development in game engines, virtual reality (VR) technologies, which immerse users inside a synthetic environment, became very popular and were increasingly integrated into the visualisation of geospatial data. In the Covid-19 pandemic, restricting people's mobility, the interest in VR visits was rapidly increa...

In recent years, there has been a markedly increase in temperatures of the Earth's surface including oceans and seas due to global warming. Mucilage, or sea saliva observed in the inland seas and bays is one of the destructive results of this phenomenon. Mucilage formations have been widely observed in May 2021 in the Marmara Sea, especially in...

Global warming threatens ecosystems through rising temperatures, increasing sea levels, drought, and extreme weather conditions. The natural balance of seas and oceans is also at stake with recent outbreaks of mucilage events all over the world. The mucilage phenomenon, which has been frequently observed in the Adriatic and Tyrrhenian seas, has tak...

For the estimation of a dense disparity map from a rectified space-borne stereo image pair and generation of the most qualified digital surface model (DSM), new image matching algorithms are being developed permanently. This study has two main goals as the DSM quality validation of Worldview-4 (WV-4), which offer the highest ground sampling distanc...

German Aerospace Centre released TanDEM-X 90 m (TDM90) global digital elevation model (GDEM) as freely available in October, 2018 and declared that it describes all Earth’s landmasses pole to pole with 1 m absolute height accuracy which could not been achieved by previous space-borne GDEMs. In this study, the coherence level of TDM90 with SRTM90 an...

Küresel ısınmanın karasal alanların yanında denizel alanlarda da doğal dengeyi bozan etkileri bulunmaktadır. Bu bozucu etkilerden biri olan müsilaj ya da deniz salyası, iç deniz ve körfezlerde ortaya çıkan doğal felaketlerden biridir. Müsilaj, Marmara Denizi’nde 2021 yılının Mayıs ayından itibaren hızlı bir şekilde yayılarak akıntı ve rüzgâr etkisi...

Global warming has effects that disrupt the natural balance in marine areas as well as terrestrial areas. One of these disruptive effects, mucilage, or sea saliva, is one of the natural disasters in the inland seas and bays. Mucilage has been spreading rapidly in the Sea of Marmara since May 2021 and has been effective in the Gemlik and Izmit bays,...

Bu çalışmada, sulama suyu amaçlı kullanılan Aydınlar (Gülüç) çayının fiziko-kimyasal parametreler açısından su kalitesi incelenmiş ve insansız hava aracı (İHA) verilerinin spektral analizi ile karşılaştırmalı değerlendirmeleri yapılmıştır. Çalışma kapsamında, su kalitesini belirlemek için üç farklı numune alım noktası belirlenmiş ve Haziran 2019 (k...

Son dönemde Marmara Denizi’nde yoğunlukla gözlemlenen; görsel, ekolojik ve ticari yönlerden sebep olduğu olumsuz etkileri nedeniyle kamuoyunun gündemine oturan deniz salyası sadece bugün değil geleceğimizi için de tehlike oluşturuyor. Bu bağlamda Türkiye Bilimler Akademisi Başkanlığı, konusunda uzman bilim insanları bu çevre sorununu değerlendirmel...

Lokal hareket işaretleri ile iki boyutlu görüntü dizilerinin birleşiminden üç boyutlu (3B) yapıları kestirebilmek için geliştirilmiş Hareketten Yapı (Structure From Motion, SFM) fotogrametrik görüntü eşleştirme algoritması, yeni nesil ve yaygın olarak kullanılan bulut tabanlı görüntü eşleştirme yazılımlarının temel prensibidir. Bu yazılımlar ortak...

In 2016, DigitalGlobe’s third-generation commercial Earth observation satellite WorldView-4 (WV-4), which offered 31 cm spatial resolution for panchromatic imagery, was launched and was active up to January 2019. Together with WorldView-3, this is the highest ground resolution of civilian optical space-borne missions. In this study, the information...

Following RASAT, Göktürk-2, placed into its orbit as Turkey's second domestic production of earth observation, has three times higher spatial resolution (2.5 m) than RASAT and has much more advanced stereo vision capability. However, like all-optical imaging satellites, Göktürk-2 has problems in data quality due to reasons such as sensor geometry,...

In 2007, synthetic aperture radar (SAR) imaging was modified by TerraSAR-X (TSX); this second-generation SAR satellite offers up to 1 m of spatial resolution. The satellite is capable of interferometric SAR (InSAR), which permits the generation of digital surface models (DSMs). TSX was designed for monostatic InSAR imaging, but the potential for ac...

Görüntüden yapısal model oluşturma (Structure from motion-SFM) algoritması, güncel bir trend olan optik bileşenli İnsansız Hava Aracı (İHA) ile toplanan veri setlerinden azami düzeyde fayda sağlamak için kullanılan yazılımlara entegre temel bir görüntü eşleme yaklaşımıdır. Her ne kadar görüntü eşleme ve yoğun nokta bulutu yazılımları ortak algoritm...

Structure from motion (SFM) matching algorithm is the basic principle of new generation and widely used image matching software. Although these software work in common principle, their final products may contain different characteristics and distortions depending on their buried parameters. In the literature, there is lack of publishments which com...

Global digital elevation models (GDEMs), the three dimensional digital cartographic representation of the Earth topography, have a crucial impact on many geo-spatial analyses. In these days, recently released ALOS World 3D 30 m (AW3D30) and 1 arc-second (~30 m) Shuttle Radar Topography Mission (SRTM) C-band GDEMs are very popular and widely in dema...

In the mining industry the aggregates sector has an important size in terms of production quantity. Most of the aggregates produced are from natural resources (sand, gravel, crushed rock) in surface quarries. Using traditional ground-based surveying methods to calculate the volume of aggregate stockpiles means a surveyor team must take their equipm...

With significant technological improvements on earth observation instruments, three dimensional space-borne remote sensing data became indispensable for modelling large areas and continents. To acquire high resolution 3D earth data, actual optical and synthetic aperture radar (SAR) satellite missions are launched frequently. Korean Multi-Purpose Sa...

The quantitative model of the Earth is provided by optical and radar space-borne remote sensing global digital elevation models (GDEMs). GDEMs are fundamental for many geo-spatial analysis and demanded by several applications that need topographical data. Recently released ALOS World 3D 30 m (AW3D30) and 1 arc-second (~ 30 m) Shuttle Radar Topograp...

Nowadays, fast developing space-borne and airborne remote sensing technologies became indispensable for land related engineering disciplines such as mapping, geology, environment, mining and forestry. The new technologies, provide more qualified and rapid achievable outcomes, are adopted permanently. The description of the topographic surface becam...

ZET Structure-from-motion (SfM) tekniğini kullanan düşük maliyetli dijital fotogrametri, dijital kamera kullanan hemen hemen herkesin fiziksel ortamın yoğun nokta bulutu modelleri oluşturmasını mümkün kılmıştır. Ancak, model üretimi için gerekli fotoğrafların çekimi, kaynakları sınırlı olan veya belirli konumlara sınırlı erişimi olanlara bir sorun...

In space-borne remote sensing, one of the most significant tasks is the three-dimensional (3D) surface modelling performance of optical and synthetic aperture radar (SAR) satellite missions. In this study, the quality of Sentinel-1A (S-1A) and Advanced Land Observing Satellite (ALOS) World 3D 30 m (AW3D30) Digital Surface Models (DSMs) was comprehe...

Bu çalışmada, 2007 yılından günümüze dek yörüngeye oturtulan ve yeni nesil yapay açıklı radar (SAR) uyduları olarak betimlenen misyonların lideri konumundaki TerraSAR-X (TSX) uydusundan elde edilen dijital yüzey modelleri (DYM) üzerinde zamansal baz uzunluğunun etki analizi gerçekleştirilmiştir. Uyduların aynı bölge üzerinden iki farklı geçişi aras...

Airborne Laser Scanning (ALS) is one of the most actual remote sensing technologies and accepted as an alternative technology to the traditional photogrammetry by the advantage of providing dense, precise and low-cost point clouds and accurate three dimensional digital surface and terrain models. However, the technique could not be utilized suffici...

Latterly, unmanned air vehicle (UAV) is one of the most actual and effective mobile mapping technologies. With the advantage of low cost, rapid and periodically data acquisition ability, UAV is more preferred against traditional high altitude photogrammetry by large variety of land-related professions. At this point, a question comes into mind, wha...

In space-borne remote sensing, correct three dimensional (3D) modeling of the Earth surface is one of the most significant goals. Up to date, several synthetic aperture radar (SAR) and optical space missions were realized to achieve the digital elevation data in global coverage. In this study, we aimed to compare the potentials of digital surface m...

Son yıllarda 3 boyutlu derinlik analizinin çok çeşitli uygulamalarda kullanılır olması, üzerinde yoğun şekilde çalışılmasının önünü açmıştır. Kullanım alanları üç boyutlu modelleme, tersine mühendislik, sanal ve artırılmış gerçeklik, otonom araçları gibi engel tespitini örnek olabileceği gibi haritacılık, arkeolojik model üretiminde de hızla yerini...

In parallel with the improvement of laser scanning technologies, dense point clouds which provide the detailed description of terrain and non-terrain objects became indispensable for remote-sensing data users. Owing to the large demand and rapid development of novel processing software such as Agisoft Photoscan and Pix4D, point clouds were started...

By means of providing dense, precise, low-cost and periodical point clouds and accurate three dimensional digital surface and terrain models of target areas, Airborne Laser Scanning (ALS) became respectable in a short time in remote sensing technologies and accepted as an alternative method to the photogrammetry especially in financially strong Eur...

Zusammenfassung: Mit WorldView-4 steht ein zweiter zivil verfügbarer optischer Satellit mit einer Bodenauflösung von 31cm zur Verfügung, der eine Konkurrenz für Luftbilder darstellt. Im Bereich von Istanbul wurde neben einem WorldView-4 Stereomodell auch ein Kompsat-3 Stereomodell, mit 70cm Objektpixelgröße, mit flächenbasierter Bildzuordnung nach...

Yoğun, yüksek konum doğruluklu, düşük maliyetli ve periyodik nokta bulutları elde etme ve doğrudan üç boyutlu dijital yüzey ve arazi modellerini sağlayabilme gibi avantajları sayesinde Hava Kaynaklı Lazer Tarama (ALS), haritacılık başta olmak üzere yeryüzü ve ona dair verileri inceleyen bilim alanlarında oldukça sık kullanılır hâle gelmiştir. ALS,...

In last decade, thanks to the great acceleration in airborne remote sensing by unmanned air vehicle (UAV) technology, very high resolution (VHR), low-cost and periodically data became accessible for geographical information systems. Moreover, with the pros of lower altitudes, high ratios of frontal and side overlaps for stereo imaging and multichan...

Topographical and geological surveys are the main applications for correct positioning and the stability of the engineering structures and have a great impact on decision mechanism of building architecture. In parallel with the developments in geomatics engineering, technological solutions are recently possible for precise three dimensional (3D) to...