Accuracy assessment of mobile lidar system in different environments

Teknolojideki gelişmelere paralel olarak mobil lidar sistemlerinin kullanım alanları günümüzde hızla artmaktadır. Özellikle GNSS ile konum belirlemenin mümkün olmadığı kapalı alanlarda SLAM algoritmalarının sağladığı avantajlar ile haritalama çalışmaları yüksek doğrulukta hızda yapılabilmektedir. Bu çalışmada, geliştirilen bir mobil lidar sistemi ile ağaçlık alan, kapalı alan ve dış mekanda yapılan ölçmeler sonucunda söz konusu alanların üç boyutlu modelleri üretilmiş ve üretilen modellerin doğruluk analizi yapılarak, GNSS ile konumlamanın mümkün olmadığı durumlarda mobil lidar sistemlerinin doğrulukları araştırılmıştır. Yapılan testler sonucunda geliştirilen mobil lidar sistemi ile ağaçlık alanlar, kapalı alanlar ve dış mekanlarda yapılan çalışmalar için sırasıyla ±2.1 cm, ±2.4 cm ve ±3.0 cm standart sapma değerleri elde edilmiştir. Bu sonuçlara göre sistemin orman envanterinin belirlenmesi çalışmalarında, kapalı ve açık alanlarda yapılacak mimari rölöve vb çalışmalarda kullanılabileceği öngörülmektedir.Depending on the developments in technology, the usage areas of mobile lidar systems are increasing rapidly today. With the advantages of SLAM algorithms, mapping studies can be performed with high accuracy, especially in areas where positioning is not possible with GNSS. In this study, with a developed mobile lidar system, three-dimensional models of the different areas were produced as a result of measurements made in woodland, indoor and outdoor areas, and the accuracy of the produced models was investigated in cases where positioning with GNSS was not possible. As a result of the tests, ±2.1 cm, ±2.4 cm and ±3.0 cm standard deviation values were obtained, respectively, for the studies carried out in woodland, indoor areas and outdoors with the mobile lidar system developed

Accuracy assessment of global digital elevation models and generated digital elevation models from Google Earth Pro data

Farklı ölçme ve uzaktan algılama teknikleri ile elde edilen verilerden üretilen Sayısal Yükseklik Modelleri (SYM) verileri yükseklik bilgisi gerektiren birçok uygulamada kullanılmaktadır. LIDAR (Light Detection and Ranging) teknolojisinin son dönemlerde gelişmesi ile araziye ait nokta bulutu verisi üretimi için havadan LIDAR tekniği, uygun arazi koşullarının sağlanması halinde cm doğruluğunda SYM’nin üretilebileceği sistemler haline gelmiştir. Çalışmada, elipsoidal yükseklik verisine sahip havadan LIDAR yöntemiyle elde edilmiş nokta bulutu referans veri olarak kullanılarak beş farklı enterpolasyon yöntemi ile SYM’ler oluşturulmuş, Google Earth Pro(GEP)’dan iki farklı yoğunlukta elde edilmiş yükseklik verileri kullanılarak oluşturulan SYM’ler ile karşılaştırılmıştır. Yine LIDAR ile elde edilen SYM’leri, SRTM (Shuttle Radar Topography Mission) ve ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) global SYM’leri ile karşılaştırılmıştır. GEP’dan elde edilen SYM’lerinin diğer iki SYM’ine göre daha iyi sonuçlar verdiği görülmüştür. GEP ile üretilen SYM ile 3,44 m doğruluk elde ederken, SRTM ve ASTER GDEM verilerinin doğruluğu sırasıyla 4,05 m ve 5,88 m'dir.Digital Elevation Models (DEM) obtained by different sources are used in many applications that require height information. With the recent development of LIDAR (Light Detection and Ranging) technology, the aerial LIDAR technique is commonly used to collect point cloud data for producing DEM in cm accuracy. In the study, DEMs were created with five different interpolation methods using the point clouds. Firstly, DEM was produced with point groups of two different densities selected from Google Earth Pro. Point clouds obtained from airborne LIDAR were used as reference data. Thus, the effect of different point densities and interpolation methods on DEM production with Google Earth Pro was examined. Additionally, DEMs obtained with LIDAR were compared with SRTM (Shuttle Radar Topography Mission) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) DEMs. DEMs obtained from Google Earth PRO give better results than the other two DEMs. DEMs produced with GEP achieve an accuracy of 3.44 m, while the accuracy of SRTM and ASTER GDEM data is 4.05 m and 5.88 m, respectively

GNSS station design for global climate change monitoring in Antarctica: ınstallation of TUR1 and TUR2 GNSS stations on Horseshoe Island in Antarctica During The 4th Turkish Antarctic Science Expedition

Son yıllarda uzay tabanlı konumlama sistemleri, GNSS Meteorolojisi ve GNSS Reflektometresi teknikleri kullanılarak gözlemlenen atmosferik su buharı, deniz, buz ve kar seviyeleri gibi önemli parametrelerle küresel iklim değişikliğinin izlenmesinde etkili bir destekleyici araç haline gelmiştir. Küresel ölçekte tüm bölgelerden daha hızlı ısınan Antarktika'da iklim değişikliğini incelemek, gelecekteki iklim değişikliğini daha doğru tahmin etmek için çok önemlidir. Dünya'nın iklim değişikliği etkilerinin izlenebilmesi amacıyla, 118Y322 No’lu TÜBİTAK projesi kapsamında GNSS Meteorolojisi ve GNSS Reflektometresi teknikleri ile 24 Şubat 2020 tarihinden itibaren Antarktika’da atmosferik su buharı değişimleri, kar derinliği ve buz kalınlığı değişimleri gözlemlenmektedir. Bu çalışmada, Troposfer ve Deniz Seviyesi Gözlem İstasyonu (TUR1) ile Troposfer ve Kar / Buz Seviyesi Gözlem İstasyonunun (TUR2) tasarım çalışmaları ve 4. Ulusal Antarktika Bilim Seferi’nde Antarktika Horseshoe Adası’na kurulum aşamaları anlatılmıştır. Bu çalışmalar, meteorolojik koşullar, şebekeden bağımsız ve batarya ile bütünleşik enerji sisteminin en sağlıklı şekilde güneş ve rüzgâr enerjisinden beslenmesi ve bölgede oluşabilecek buzul oluşumu ve kayaç parçalanması gibi jeolojik parametreler de göz önüne alınarak yapılmıştır.In recent years, space-based positioning systems have become an effective supporting tool for monitoring global climate change by important parameters such as atmospheric water vapor, sea, ice and snow levels observed by using GNSS Meteorology and GNSS Reflectometry techniques. Studying climate change in Antarctica, which is warming faster than all of the regions on a global scale, is very important to predict future climate change more accurately. In order to monitor climate change effects of the Earth, tropospheric water vapor variations, snow depth and ice thickness changes have been observing in Antarctica since 24 February 2020 by means of GNSS Meteorology and GNSS Reflectometry techniques within the scope of the TUBITAK Project No. 118Y322 In this study, designing studies of Troposphere and Sea Level Observation Station (TUR1) and Troposphere and Snow / Ice Level Observation Station (TUR2) and installation steps to Horseshoe Island in Antarctica during the 4th National Antarctic Science Expedition are explained. These studies was carried out by taking into account the meteorological conditions, the healthiest feeding of the off grid battery integrated energy system from solar and wind energy and geological parameters such as glacial formation and rock fragmentation that may occur in the region

Design of double-egg curve in the link roads of transportation networks

Skretanja s glavnih cesta do naselja postižu se prilaznim putevima. Zbog sigurnosti ovih skretanja, zakretni polumjeri trebaju biti veliki. Međutim, nije uvijek moguće napraviti ova skretanja kružnim lukovima velikog polumjera, budući da različiti čimbenici, kao što su topografija, položaj naselja, problemi koje je nemoguće prevladati te ekonomski uvjeti, ne dopuštaju izradu takve trase. Umjesto toga je, zbog prometa, poželjna linearna varijacija zakrivljenosti linije ili održavanje konstantne vrijednosti zakrivljenosti linije. Takva je klotoidna krivina jajeta. U mnogim se aplikacijama primjenjuje jednostruki ili dvostruki tip takvih klotoidnih zavoja. U ovom se radu proračun i projektiranje dvostruko kružnih zavoja detaljno objašnjavaju jednadžbama i slikama. Primjer projekta dvostruko kružnog zavoja primijenjen u skretanjima s glavne ceste u prometnim mrežama daje se zbog boljeg razumijevanja samog predmeta. U tabeli su prikazane glavne točke geometrije rotacije s koordinatama pomoćnih točaka. Nadamo se da će osnovna svrha ove analize, teorija i detaljni proračuni dvostruko kružnog zavoja i njihova primjena kojom se omogućuje sigurnija i udobnija vožnja, biti od koristi praktičarima.The turns from highways to settlement areas are achieved by link roads. For the safety of these turns, turning radii are required to be large. However, it is not always possible to achieve these turnings by means of arcs of circle with large radius, as different factors, such as topography, the state of settlement, problems impossible to overcome and economic conditions, do not allow designing such a route. Instead, for the sake of traffic, linear variation of the line curvature or maintaining the line curvature at constant value is highly desirable. One of the line geometries is the clothoid egg curve. Single and double type clothoid egg curves are used in many applications. In this study, the calculation and design of double-egg curve are explained by equations and figures in detail. For the design of two egg curves used in rotation from main road to connecting road in transportation networks as application, an example is provided for a better understanding of the subject. The main points of rotation geometry with the coordinates of auxiliary points and other intermediate results are given in a table. The main purpose of this study, the theory and calculations of two egg curves will provide basis to practitioners on a sample in a detailed way. By the fulfilment of design and its calculation of this rotation geometry which provides safer and more comfortable driving, it is hoped to be useful for practitioners

Mapping of Glaciers on Horseshoe Island, Antarctic Peninsula, with Deep Learning Based on High-Resolution Orthophoto

Antarctica plays a key role in the hydrological cycle of the Earth’s climate system, with an ice sheet that is the largest block of ice that reserves Earth’s 90% of total ice volume and 70% of fresh water. Furthermore, the sustainability of the region is an important concern due to the challenges posed by melting glaciers that preserve the Earth’s heat balance by interacting with the Southern Ocean. Therefore, the monitoring of glaciers based on advanced deep learning approaches offers vital outcomes that are of great importance in revealing the effects of global warming. In this study, recent deep learning approaches were investigated in terms of their accuracy for the segmentation of glacier landforms in the Antarctic Peninsula. For this purpose, high-resolution orthophotos were generated based on UAV photogrammetry within the Sixth Turkish Antarctic Expedition in 2022. Segformer, DeepLabv3+ and K-Net deep learning methods were comparatively analyzed in terms of their accuracy. The results showed that K-Net provided efficient results with 99.62% accuracy, 99.58% intersection over union, 99.82% precision, 99.76% recall and 99.79% F1-score. Visual inspections also revealed that K-Net was able to preserve the fine details around the edges of the glaciers. Our proposed deep-learning-based method provides an accurate and sustainable solution for automatic glacier segmentation and monitoring

Characteristics of the Snow Cover in East and West Antarctica and Their 20-Year Trends Retrieved from Satellite Remote Sensing Data

The aim of this study was to make a comparative analysis of the state of the snow surface in East and West Antarctica, including changes in snow cover characteristics during the past two decades. To do so, we used the ASAR (Antarctic Snow Albedo Retriever) algorithm, which processes satellite data and retrieves an effective snow grain size and a fraction of rocks not covered by snow, to process the MODIS data throughout the entire period of its operation (up to now). We have chosen several test areas (approximately 30 × 30 km2) to study the state of the snow cover on Enderby Land (East Antarctica), on the coast of the Ross Sea (the Transantarctic Mountains), and the Antarctic Peninsula (West Antarctica). As a result, we have plotted and analyzed the time series of the effective snow grain size and rock fraction in these areas across the last 20 years. We have found weak negative trends for the effective grain size on the coast of Enderby Land and the Ross Sea. The rock fraction does not demonstrate any trend. The study of snow cover trends on a continental scale can contribute to the investigation of environmental changes in Antarctica