Alen Berta - Academia.edu (original) (raw)

Papers by Alen Berta

Research paper thumbnail of Sensor-agnostic DEM-assisted ML-based modeling of the flood extent in conditions hindered by clouds or satellite revisit time

Earth Resources and Environmental Remote Sensing/GIS Applications XIII

Research paper thumbnail of Forest biomass assessment by LIDAR technology in degraded forests of hilly and lowland vegetation area in central Croatia

Radi praćenja količine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i praćenj... more Radi praćenja količine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i praćenja promjena, pozitivnih i negativnih, u veličini rezervoara (ponora) ugljika potrebno je razviti brze i jednostavne metode pomoću kojih se u vrlo kratkom roku mogu sakupiti velike količine podataka na velikom području, potrebnih za obračun ovih parametara. To se može postići implementirajući LIDAR tehnologiju za obračun nadzemne biomase vegetacije na velikim područjima i posljedično obračun vezanog ugljika odnosno ugljičnog dioksida, što u Republici Hrvatskoj predstavlja prvo istraživanje ovakvog tipa. Jedan od ciljeva ovog istraživanja je izraditi model za utvrđivanje nadzemne biomase degradiranih šumskih područja u stadiju šikara (hipoteza 1), što je jedan od glavnih nedostajućih podataka pri određivanju količine vezanog ugljika i promjena u rezervoaru ugljika prilikom izrade Nacionalnog izviješća o stakleničkim plinovima. Također će se utvrditi utjecaj manjih gustoća oblaka točaka na k...

Research paper thumbnail of Monitoring age of private owned Holm oak (Quercus ilex L.) and Pubescent oak (Quercus pubescens Willd.) forests in Croatian Mediterranean and sub-Mediterranean with Sentinel 2 multispectral satellite

EGU General Assembly Conference Abstracts, Apr 1, 2018

Research paper thumbnail of Improving Sentinel 2 based forest type classification models with multitemporal Sentinel 1 data and data mining

Research paper thumbnail of New findings for GHG National Inventory Report-woodstocks of the scrublands and maquis in the Croatian Mediterranean and sub-Mediterranean

Research paper thumbnail of Remote Sensing in Forest Ecosystem Monitoring on the Area of the Planned Danube-Sava Multipurpose Channel

Research paper thumbnail of Testing the efficiency of an automated method developed to improve vertical accuracy of photogrammetric DTM in the lowland forest areas

Research paper thumbnail of The impact of ALS and photogrammetric DTM on plot-level tree height estimates from UAV-based images

Research paper thumbnail of LIDAR for nature protection- Forest park Marjan

Research paper thumbnail of Accuracy Assessment of Digital Terrain Models of Lowland Pedunculate Oak Forests Derived from Airborne Laser Scanning and Photogrammetry

Digital terrain models (DTMs) present important data source for different applications in environ... more Digital terrain models (DTMs) present important data source for different applications in environmental disciplines including forestry. At regional level, DTMs are commonly created using airborne digital photogrammetry or airborne laser scanning (ALS) technology. This study aims to evaluate the vertical accuracy of DTMs of different spatial resolutions derived from high-density ALS data and existing photogrammetric (PHM) data in the dense lowland even-aged pedunculate oak forests located in the Pokupsko basin in Central Croatia. As expected, the assessment of DTMs' vertical accuracy using 22 ground checkpoints shows higher accuracy for ALS-derived than for PHM-derived DTMs. Concerning the different resolutions of ALS-derived (0.5 m, 1 m, 2 m, 5 m) and PHM-derived DTMs (0.5 m, 1 m, 2 m, 5 m, 8 m) compared in this research, the ALS-derived DTM with the finest resolution of 0.5 m shows the highest accuracy. The root mean square error (RMSE) and mean error (ME) values for ALS-derived DTMs range from 0.14 m to 0.15 m and from 0.09 to 0.12 m, respectively, and the values decrease with decreasing spatial resolution. For the PHM-derived DTMs, the RMSE and ME values are almost identical regardless of resolution and they are 0.35 m and 0.17 m, respectively. The findings suggest that the 8 m spatial resolution is optimal for a given photogrammetric data, and no finer than 8 m spatial resolution is required. This research also reveals that the national digital photogrammetric data in the study area contain certain errors (outliers) specific to the terrain type, which could considerably affect the DTM accuracy. Thus, preliminary evaluation of photogrammetric data should be done to eliminate possible outliers prior to the DTM generation in lowland forests with flat terrain. In the absence of ALS data, the finding in this research could be of interests to countries, which still rely on similar photogrammetric data for DTM generation.

Research paper thumbnail of Remote Sensing in Eutrophication Monitoring of Water Bodies Using Sentinel 2 Imagery

Research paper thumbnail of LPIS as a basis for automatic land use classification?

Research paper thumbnail of Methods for forest carbon pool measurement

The greenhouse effect is undoubtedly one of the most difficult modern day environmental problems,... more The greenhouse effect is undoubtedly one of the most difficult modern day environmental problems, and the biggest culprit for it, in terms of emitted quantities, is CO2 – carbon dioxide. Its current concentration is higher than ever in the history of Earth. Forests, as one of the carbon sinks (along with seas and soil) may play a decisive role in mitigation or reduction of emitted CO2. All living creatures on Earth are made up of a certain amount of carbon, and trees are the only ones who absorb it from the atmosphere, and build it in their biomass through the products of photosynthesis. Therefore, the first problem is how to determine the volume i.e. the biomass weight of a tree, a stand or an area, and then determine the percentage of carbon in wood mass. In this paper, the author provides an overview of available methods and procedures for assessments i.e. calculations of sequestered carbon and possibilities of carbon sequestration. However, assessments of greenhouse gases’ dynamics inevitably result in uncertainties due to various interpretations of carbon sources and outflow, assumptions, units or usage of simplified results with average values. In addition to that, ambiguities also arise from different or inadequately scientifically researched core processes leading to emission or removal of carbon. In order to encompass entire carbon cycle in a forest ecosystem it is necessary to include: bound carbon in the soil and circulation of carbon in soil; carbon depot in main forest semi-products and products as well as emissions originating from these products by decomposition or burning; emissions originating from forest utilisation operations and transport of wood mass. An attempt of harmonization of data from various parts of the world with the aim of creating a report that can be used to monitor carbon emission and drain on a global scale is presented in the handbook Good Practice Guidance on Land Use, Land Use Changes and Forestry (GPG LULUCF). This handbook was issued by the Intergovernmental Panel on Climate Change founded in 1988 by the United Nations, World Meteorological Organisation and United Nations Environment Progamme (UNEP).

Research paper thumbnail of Usporedba lidarskih i terenskih podataka pri izmjeri visine stabala u urbanim područjima

U radu je na temelju podataka dobivenih laserskim skeniranjem iz zraka prikazana obrada 3D oblaka... more U radu je na temelju podataka dobivenih laserskim skeniranjem iz zraka prikazana obrada 3D oblaka točaka te različiti načini i mogućnosti uporabe podataka pri praćenju i izmjeri vegetacije urbanih područja. U istraživanju su korišteni lidarski (engl. LiDAR = Light Detection and Ranging) podaci dobiveni u Zagrebu, točnije na Lenucijevoj potkovi, na Trgu Nikole Šubića Zrinskoga. Na istraživanom području za svako je locirano stablo određena vrsta i mjerena njegova visina (m) ultrazvučnim visinomjerom Vertex III. Terenskom izmjerom obuhvaćeno je 146 stabala (od toga 140 hibridnih platana (Platanus × hispanica) i 6 stabala javora mliječa (Acer platanoides L.). Prosječna izmjerena visina uređajem Vertex III iznosila je 24,0 m s rasponom od 5,60 m za najniže stablo do 36,0 m za najviše izmjereno stablo. Srednji prsni promjer iznosio je 74 cm s rasponom od 8 cm do 160 cm. Laserskim skeniranjem iz zraka i obradom prikupljenih podataka dobiven je georeferencirani 3D oblak točaka razvrstan u četiri razreda kao proizvod obrade sirovih podataka u softveru LAStools te prikazan u softveru QTM za vizualizaciju oblaka točaka.

Research paper thumbnail of Procjena šumske biomase pomoći LIDAR tehnologije u degradiranim šumama brežuljkastoga i nizinskoga vegetacijskog pojasa u središnjoj Hrvatskoj

Radi pracenja kolicine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i pracenj... more Radi pracenja kolicine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i pracenja promjena, pozitivnih i negativnih, u velicini r

Research paper thumbnail of Moss survey 2010 in Croatia

Research paper thumbnail of Cost-Benefit Analysis in Exploitation of Stone

Research paper thumbnail of The Evaluation of Photogrammetry-Based DSM from Low-Cost UAV by LiDAR-Based DSM

South-east European forestry, 2017

Today we are witnessing the growing use of unmanned aerial vehicles (UAVs) for monitoring purpose... more Today we are witnessing the growing use of unmanned aerial vehicles (UAVs) for monitoring purposes. Potential applications of UAVs can be found in agricultural, forestry, and environmental sciences; surveillance, and reconnaissance; aerial monitoring in engineering; cultural heritage; and traditional surveying, conventional mapping and photogrammetry, and cadastral applications [1]. Due to various construction solutions UAVs are flexibile to solve various surveying tasks. Compared to the classical terrestrial survey, UAVs are capable to cover considerably larger areas in short time period, as well as to survey distant or inaccessible areas (e.g. distant forest and mined areas) and objects (e.g. high buildings). The flexibility of photogrammetric surveying methods along with the selection of the adequate cameras and lenses results in adaption of the measuring platform (UAV) to the needs

Research paper thumbnail of Site Index and Volume Growth Percentage Determination for Privately Owned Uneven-aged Stands of Quercus pubescens and Quercus ilex along the Croatian Adriatic Coast

South-east European forestry, 2019

Background and Purpose: Although organized forestry has existed in Croatia for more than 250 year... more Background and Purpose: Although organized forestry has existed in Croatia for more than 250 years, this mostly entailed state forests. During the last decade, Extension Services have started to support the development of forest management plans for privately owned forests. Lately, FMPs have been developed for nearly 3/4 of privately owned forests in Croatia. During the creation of those plans, yield tables and normal models for state-owned forests, primarily even-aged stands with long-time management, were used because similar data was not developed for uneven-aged and poorly managed forests. This research encompasses privately owned forests in the Croatian Mediterranean and sub-Mediterranean regions where holm oak ( Quercus ilex L.) and downy oak ( Quercus pubescens Willd.) are the prevailing species in forest stands. The main goal was to determine site indices revealed in the analysis of yearly radial increments and to create relevant yield tables. Materials and Methods: In this ...

Research paper thumbnail of Posjedovne i površinske značajke šuma šumoposjednika u Hrvatskoj prema regijama

Šumarski list, 2017

Privatne šume prema Šumskogospodarskoj osnovi RH 2006-2015 zauzimaju 22 % ukupne površine šuma i ... more Privatne šume prema Šumskogospodarskoj osnovi RH 2006-2015 zauzimaju 22 % ukupne površine šuma i šumskog zemljišta u RH tj. oko 600.000 ha. Neke od značajki privatnih šuma su: da se radi o sitnim česticama i posjedima, na istoj površini nalazi se veći broj posjednika te iznimna nesređenost podataka u katastru. U ovom radu obrađeni su podaci o česticama i posjednicima iz 319 katastarskih općina (KO) raspoređenih u 5 regija Republike Hrvatske tj. u 53 gospodarske jedinice šuma šumoposjednika. Površinski uzorak predstavlja 8,74 % RH tj. prema ŠGO RH 15,69 % privatnih šuma RH. Osim prikaza sumarnih podataka po regijama, provedene su i dvije klaster analize radi dodatne karakterizacije regija. Prva klaster analiza se odnosi na varijable posjedništva: srednja površina čestica unutar KO obuhvaćenih programima gospodarenja šumama šumoposjednika (u daljem tekstu Programima), srednja površina posjeda unutar KO obuhvaćenim Programima te srednja količina posjednika na posjedovnim listovima unut...

Research paper thumbnail of Sensor-agnostic DEM-assisted ML-based modeling of the flood extent in conditions hindered by clouds or satellite revisit time

Earth Resources and Environmental Remote Sensing/GIS Applications XIII

Research paper thumbnail of Forest biomass assessment by LIDAR technology in degraded forests of hilly and lowland vegetation area in central Croatia

Radi praćenja količine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i praćenj... more Radi praćenja količine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i praćenja promjena, pozitivnih i negativnih, u veličini rezervoara (ponora) ugljika potrebno je razviti brze i jednostavne metode pomoću kojih se u vrlo kratkom roku mogu sakupiti velike količine podataka na velikom području, potrebnih za obračun ovih parametara. To se može postići implementirajući LIDAR tehnologiju za obračun nadzemne biomase vegetacije na velikim područjima i posljedično obračun vezanog ugljika odnosno ugljičnog dioksida, što u Republici Hrvatskoj predstavlja prvo istraživanje ovakvog tipa. Jedan od ciljeva ovog istraživanja je izraditi model za utvrđivanje nadzemne biomase degradiranih šumskih područja u stadiju šikara (hipoteza 1), što je jedan od glavnih nedostajućih podataka pri određivanju količine vezanog ugljika i promjena u rezervoaru ugljika prilikom izrade Nacionalnog izviješća o stakleničkim plinovima. Također će se utvrditi utjecaj manjih gustoća oblaka točaka na k...

Research paper thumbnail of Monitoring age of private owned Holm oak (Quercus ilex L.) and Pubescent oak (Quercus pubescens Willd.) forests in Croatian Mediterranean and sub-Mediterranean with Sentinel 2 multispectral satellite

EGU General Assembly Conference Abstracts, Apr 1, 2018

Research paper thumbnail of Improving Sentinel 2 based forest type classification models with multitemporal Sentinel 1 data and data mining

Research paper thumbnail of New findings for GHG National Inventory Report-woodstocks of the scrublands and maquis in the Croatian Mediterranean and sub-Mediterranean

Research paper thumbnail of Remote Sensing in Forest Ecosystem Monitoring on the Area of the Planned Danube-Sava Multipurpose Channel

Research paper thumbnail of Testing the efficiency of an automated method developed to improve vertical accuracy of photogrammetric DTM in the lowland forest areas

Research paper thumbnail of The impact of ALS and photogrammetric DTM on plot-level tree height estimates from UAV-based images

Research paper thumbnail of LIDAR for nature protection- Forest park Marjan

Research paper thumbnail of Accuracy Assessment of Digital Terrain Models of Lowland Pedunculate Oak Forests Derived from Airborne Laser Scanning and Photogrammetry

Digital terrain models (DTMs) present important data source for different applications in environ... more Digital terrain models (DTMs) present important data source for different applications in environmental disciplines including forestry. At regional level, DTMs are commonly created using airborne digital photogrammetry or airborne laser scanning (ALS) technology. This study aims to evaluate the vertical accuracy of DTMs of different spatial resolutions derived from high-density ALS data and existing photogrammetric (PHM) data in the dense lowland even-aged pedunculate oak forests located in the Pokupsko basin in Central Croatia. As expected, the assessment of DTMs' vertical accuracy using 22 ground checkpoints shows higher accuracy for ALS-derived than for PHM-derived DTMs. Concerning the different resolutions of ALS-derived (0.5 m, 1 m, 2 m, 5 m) and PHM-derived DTMs (0.5 m, 1 m, 2 m, 5 m, 8 m) compared in this research, the ALS-derived DTM with the finest resolution of 0.5 m shows the highest accuracy. The root mean square error (RMSE) and mean error (ME) values for ALS-derived DTMs range from 0.14 m to 0.15 m and from 0.09 to 0.12 m, respectively, and the values decrease with decreasing spatial resolution. For the PHM-derived DTMs, the RMSE and ME values are almost identical regardless of resolution and they are 0.35 m and 0.17 m, respectively. The findings suggest that the 8 m spatial resolution is optimal for a given photogrammetric data, and no finer than 8 m spatial resolution is required. This research also reveals that the national digital photogrammetric data in the study area contain certain errors (outliers) specific to the terrain type, which could considerably affect the DTM accuracy. Thus, preliminary evaluation of photogrammetric data should be done to eliminate possible outliers prior to the DTM generation in lowland forests with flat terrain. In the absence of ALS data, the finding in this research could be of interests to countries, which still rely on similar photogrammetric data for DTM generation.

Research paper thumbnail of Remote Sensing in Eutrophication Monitoring of Water Bodies Using Sentinel 2 Imagery

Research paper thumbnail of LPIS as a basis for automatic land use classification?

Research paper thumbnail of Methods for forest carbon pool measurement

The greenhouse effect is undoubtedly one of the most difficult modern day environmental problems,... more The greenhouse effect is undoubtedly one of the most difficult modern day environmental problems, and the biggest culprit for it, in terms of emitted quantities, is CO2 – carbon dioxide. Its current concentration is higher than ever in the history of Earth. Forests, as one of the carbon sinks (along with seas and soil) may play a decisive role in mitigation or reduction of emitted CO2. All living creatures on Earth are made up of a certain amount of carbon, and trees are the only ones who absorb it from the atmosphere, and build it in their biomass through the products of photosynthesis. Therefore, the first problem is how to determine the volume i.e. the biomass weight of a tree, a stand or an area, and then determine the percentage of carbon in wood mass. In this paper, the author provides an overview of available methods and procedures for assessments i.e. calculations of sequestered carbon and possibilities of carbon sequestration. However, assessments of greenhouse gases’ dynamics inevitably result in uncertainties due to various interpretations of carbon sources and outflow, assumptions, units or usage of simplified results with average values. In addition to that, ambiguities also arise from different or inadequately scientifically researched core processes leading to emission or removal of carbon. In order to encompass entire carbon cycle in a forest ecosystem it is necessary to include: bound carbon in the soil and circulation of carbon in soil; carbon depot in main forest semi-products and products as well as emissions originating from these products by decomposition or burning; emissions originating from forest utilisation operations and transport of wood mass. An attempt of harmonization of data from various parts of the world with the aim of creating a report that can be used to monitor carbon emission and drain on a global scale is presented in the handbook Good Practice Guidance on Land Use, Land Use Changes and Forestry (GPG LULUCF). This handbook was issued by the Intergovernmental Panel on Climate Change founded in 1988 by the United Nations, World Meteorological Organisation and United Nations Environment Progamme (UNEP).

Research paper thumbnail of Usporedba lidarskih i terenskih podataka pri izmjeri visine stabala u urbanim područjima

U radu je na temelju podataka dobivenih laserskim skeniranjem iz zraka prikazana obrada 3D oblaka... more U radu je na temelju podataka dobivenih laserskim skeniranjem iz zraka prikazana obrada 3D oblaka točaka te različiti načini i mogućnosti uporabe podataka pri praćenju i izmjeri vegetacije urbanih područja. U istraživanju su korišteni lidarski (engl. LiDAR = Light Detection and Ranging) podaci dobiveni u Zagrebu, točnije na Lenucijevoj potkovi, na Trgu Nikole Šubića Zrinskoga. Na istraživanom području za svako je locirano stablo određena vrsta i mjerena njegova visina (m) ultrazvučnim visinomjerom Vertex III. Terenskom izmjerom obuhvaćeno je 146 stabala (od toga 140 hibridnih platana (Platanus × hispanica) i 6 stabala javora mliječa (Acer platanoides L.). Prosječna izmjerena visina uređajem Vertex III iznosila je 24,0 m s rasponom od 5,60 m za najniže stablo do 36,0 m za najviše izmjereno stablo. Srednji prsni promjer iznosio je 74 cm s rasponom od 8 cm do 160 cm. Laserskim skeniranjem iz zraka i obradom prikupljenih podataka dobiven je georeferencirani 3D oblak točaka razvrstan u četiri razreda kao proizvod obrade sirovih podataka u softveru LAStools te prikazan u softveru QTM za vizualizaciju oblaka točaka.

Research paper thumbnail of Procjena šumske biomase pomoći LIDAR tehnologije u degradiranim šumama brežuljkastoga i nizinskoga vegetacijskog pojasa u središnjoj Hrvatskoj

Radi pracenja kolicine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i pracenj... more Radi pracenja kolicine vezanog (tzv. priljeva) i emitiranog (tzv. odljeva) ugljika, kao i pracenja promjena, pozitivnih i negativnih, u velicini r

Research paper thumbnail of Moss survey 2010 in Croatia

Research paper thumbnail of Cost-Benefit Analysis in Exploitation of Stone

Research paper thumbnail of The Evaluation of Photogrammetry-Based DSM from Low-Cost UAV by LiDAR-Based DSM

South-east European forestry, 2017

Today we are witnessing the growing use of unmanned aerial vehicles (UAVs) for monitoring purpose... more Today we are witnessing the growing use of unmanned aerial vehicles (UAVs) for monitoring purposes. Potential applications of UAVs can be found in agricultural, forestry, and environmental sciences; surveillance, and reconnaissance; aerial monitoring in engineering; cultural heritage; and traditional surveying, conventional mapping and photogrammetry, and cadastral applications [1]. Due to various construction solutions UAVs are flexibile to solve various surveying tasks. Compared to the classical terrestrial survey, UAVs are capable to cover considerably larger areas in short time period, as well as to survey distant or inaccessible areas (e.g. distant forest and mined areas) and objects (e.g. high buildings). The flexibility of photogrammetric surveying methods along with the selection of the adequate cameras and lenses results in adaption of the measuring platform (UAV) to the needs

Research paper thumbnail of Site Index and Volume Growth Percentage Determination for Privately Owned Uneven-aged Stands of Quercus pubescens and Quercus ilex along the Croatian Adriatic Coast

South-east European forestry, 2019

Background and Purpose: Although organized forestry has existed in Croatia for more than 250 year... more Background and Purpose: Although organized forestry has existed in Croatia for more than 250 years, this mostly entailed state forests. During the last decade, Extension Services have started to support the development of forest management plans for privately owned forests. Lately, FMPs have been developed for nearly 3/4 of privately owned forests in Croatia. During the creation of those plans, yield tables and normal models for state-owned forests, primarily even-aged stands with long-time management, were used because similar data was not developed for uneven-aged and poorly managed forests. This research encompasses privately owned forests in the Croatian Mediterranean and sub-Mediterranean regions where holm oak ( Quercus ilex L.) and downy oak ( Quercus pubescens Willd.) are the prevailing species in forest stands. The main goal was to determine site indices revealed in the analysis of yearly radial increments and to create relevant yield tables. Materials and Methods: In this ...

Research paper thumbnail of Posjedovne i površinske značajke šuma šumoposjednika u Hrvatskoj prema regijama

Šumarski list, 2017

Privatne šume prema Šumskogospodarskoj osnovi RH 2006-2015 zauzimaju 22 % ukupne površine šuma i ... more Privatne šume prema Šumskogospodarskoj osnovi RH 2006-2015 zauzimaju 22 % ukupne površine šuma i šumskog zemljišta u RH tj. oko 600.000 ha. Neke od značajki privatnih šuma su: da se radi o sitnim česticama i posjedima, na istoj površini nalazi se veći broj posjednika te iznimna nesređenost podataka u katastru. U ovom radu obrađeni su podaci o česticama i posjednicima iz 319 katastarskih općina (KO) raspoređenih u 5 regija Republike Hrvatske tj. u 53 gospodarske jedinice šuma šumoposjednika. Površinski uzorak predstavlja 8,74 % RH tj. prema ŠGO RH 15,69 % privatnih šuma RH. Osim prikaza sumarnih podataka po regijama, provedene su i dvije klaster analize radi dodatne karakterizacije regija. Prva klaster analiza se odnosi na varijable posjedništva: srednja površina čestica unutar KO obuhvaćenih programima gospodarenja šumama šumoposjednika (u daljem tekstu Programima), srednja površina posjeda unutar KO obuhvaćenim Programima te srednja količina posjednika na posjedovnim listovima unut...