Dainis Jakovels

Institute for Environmental Solutions · Remote Sensing

The overall increase of ungulate populations in modern Europe has contributed to conflicts in national economies, particularly between game management and the forestry sector. This study assessed damage risks to young pine (Pinus sylvestris L.), spruce (Picea abies (L.) H. Karst.) and aspen (Populus tremula L.) stands at two spatial scales. One lev...

The common dandelion ( Taraxacum campylodes G.E.Haglund) is known for its medicinal properties and as a non-toxic, highly nutritious edible plant. Even though the herb is mostly collected in the wild, the food and pharmaceutical industries prefer cultivated plant material. Cultivation offers the possibility to achieve predictable yields, ensure the...

Passive acoustic sensors have the potential to become a valuable complementary component in red deer Cervus elaphus monitoring providing deeper insight into the behavior of stags during the rutting period. Automation of data acquisition and processing is crucial for adaptation and wider uptake of acoustic monitoring. Therefore, an automated data pr...

Changes in the ungulate population density in the wild has impacts on both the wildlife and human society. In order to control the ungulate population movement, monitoring systems such as camera trap networks have been implemented in a non-invasive setup. However, such systems produce a large number of images as the output, hence making it very res...

Short temporal baseline regular Synthetic Aperture Radar (SAR) interferometry is a tool well suited for wide area monitoring of agricultural activities, urgently needed in European Union Common Agricultural Policy (CAP) enforcement. In this study, we demonstrate and describe in detail, how mowing and ploughing events can be identified from Sentinel...

Phytoplankton primary production (PP) in lakes play an important role in the global carbon cycle. However, monitoring the PP in lakes with traditional complicated and costly in situ sampling methods are impossible due to the large number of lakes worldwide (estimated to be 117 million lakes). In this study, bio-optical modelling and remote sensing...

Chamomilla recutita is a cross-pollinating medicinal plant widely used in traditional medicine both in Latvia and globally. In this study, we evaluated the genetic and morphological diversity as well as the chemical profiles of plants collected from semi-wild populations in Latvia as well as various varieties found in Central Europe. All samples we...

Inland waters, including lakes, are one of the key points of the carbon cycle. Using remote sensing data in lake monitoring has advantages in both temporal and spatial coverage over traditional in-situ methods that are time consuming and expensive. In this study, we compared two sensors on different Copernicus satellites: Multispectral Instrument (...

Inland waters play a critical role in our drinking water supply. Additionally, they areimportant providers of food and recreation possibilities. Inland waters are known to be opticallycomplex and more diverse than marine or ocean waters. The optical properties of natural waters areinfluenced by three different and independent sources: phytoplankton...

The aim of this work was to find the best algorithms for estimating Level-2 water quality parameters. We compared two sensors on different Copernicus satellites: MSI on Sentinel-2 and OLCI on Sentinel-3 with in-situ match-ups. The algorithms from different band ratios based on OWTs gave the best results for both satellites. The S2 outperformed S3...

Permanent grasslands (meadows and pastures) are the most common agricultural land use type covering 34% (0.65 million hectares) of agricultural land in Latvia. Conservation and proper management of these semi-natural habitats is critical to maintain their biological value, and is line with The Common Agriculture Policy (CAP). Development of Sentine...

Permanent grasslands (meadows and pastures) are the most common agricultural land use type covering 34% (0.65 million hectares) of agricultural land in Latvia. The Common Agriculture Policy (CAP) stipulates that the EU Member States have to designate permanent grasslands, ensure that farmers do not convert or plough them and that the ratio of perma...

Conference poster at First Baltic Conference on the Environmental Humanities and Social Sciences (BALTEHUMS) October 8-9, 2018

The primary goal of this study was to discover the spatial and temporal differences of lake OWTs in Latvia and Estonia during 2017. A comparison between Sentinel-2 and -3 on the matching days was carried out to understand if both satellites are suitable for classifying the water types.

Permanent grasslands (meadows and pastures) are the most common agricultural land use type covering 34% (0.65 million hectares) of agricultural land in Latvia. The Common Agriculture Policy (CAP) stipulates that the EU Member States have to designate permanent grasslands, ensure that farmers do not convert or plough them and that the ratio of perma...

Remote sensing has proved to be an accurate and reliable tool in clear water environments like oceans or the Mediterranean Sea. However, the current algorithms and methods usually fail on optically complex waters like coastal and inland waters. The whole Baltic Sea can be considered as optically complex coastal waters. Remote assessment of water qu...

Land cover mapping in Latvia is performed as part of the Corine Land Cover (CLC) initiative every six years. The advantage of CLC is the creation of a standardized nomenclature and mapping protocol comparable across all European countries, thereby making it a valuable information source at the European level. However, low spatial resolution and acc...

We highlight the options available for noninvasive optical diagnostics of reporter gene expression in mouse tibialis cranialis muscle. An in vivo multispectral imaging technique combined with fluorescence spectroscopy point measurements has been used for the transcutaneous detection of enhanced green fluorescent protein (EGFP) expression, providing...

The purpose of this paper is to offer a method for discrimination of cutaneous melanoma from benign nevus, founded on analysis of skin lesion image. At the core of method is calculation of mean and standard deviation of pixel optical density values for a few narrow spectral bands. Calculated values are compared with discriminating thresholds derive...

A commercially available point measurement device, the Mexameter ® , and an experimental RGB imaging prototype device were used for erythema index estimation of 50 rosacea patients by analysing the level of skin redness on the forehead, both cheeks and both sides of a nose. Results are compared with Clinician’s Erythema Assessment (CEA) values give...

Early diagnostics of skin cancer is of interest for dermatologists. Atypical nevi are not considered to be malignant, but are suspects that should be detected and monitored over time. The multispectral imaging system Nuance operating in spectral range 450–950 nm was adapted for clinical in vivo measurements in diffuse reflectance and fluorescence m...

Mobile platform for multimodal skin assessment has been developed. Different illumination sources allow switching between modalities. Diffuse reflectance spectral imaging is provided by five LEDs, fluorescence is excited by 405 nm LEDs, and laser speckle by 650 nm laser diode. Handheld, battery powered device includes all light sources and color ca...

Airborne hyperspectral imaging is widely used for remote sensing of environment. The choice of spectral region usually depends on the availability and cost of the sensor. Visible-to-near infrared (400-1100 nm) spectral range corresponds to spectral sensitivity of relatively cheap Si detectors therefore it is the most commonly used. The implementati...

Assessment of skin blood flow is of interest for evaluation of skin viability as well as for reflection of the overall condition of the circulatory system. Laser Doppler perfusion imaging (LDPI) and laser speckle contrast imaging (LASCI) are optical techniques used for assessment of skin perfusion. However, these systems are still too expensive and...

Electroporation and ultrasound induced sonoporation has been showed to induce plasmid DNA transfection to the mice tibialis cranialis muscle. It offers new prospects for gene therapy and cancer treatment. However, numerous experimental data are still needed to deliver the plausible explanation of the mechanisms governing DNA electro- or sono-transf...

Laser speckle contrast analysis (LASCA) offers a non-contact, full-field, and real-time mapping of capillary blood flow and can be considered as an alternative method to Laser Doppler perfusion imaging. LASCA technique has been implemented in several commercial instruments. However, these systems are still too expensive and bulky to be widely avail...

The diffuse reflectance multispectral imaging technique has been used for distant mapping of in vivo skin chromophores (hemoglobin and melanin). The fluorescence multispectral imaging is not so common for skin applications due to complicity of data acquisition and processing, but could provide additional information about skin fluorophores. Both te...

The multi-spectral imaging technique has been used for distant mapping of in-vivo skin chromophores by analyzing spectral data at each reflected image pixel and constructing 2-D maps of the relative concentrations of oxy-/deoxy-hemoglobin and melanin. Instead of using a broad visible-NIR spectral range, this study focuses on narrowed spectral band...

A prototype low-cost RGB imaging system consisting of a commercial RGB CMOS sensor, RGB light-emitting diode ring light illuminator, and a set of polarizers was designed and tested for mapping the skin erythema index, in order to monitor skin recovery after phototherapy of vascular lesions, such as hemangiomas and telangiectasias. The contrast of e...

Simple RGB method for fluorescence in vivo imaging is presented to assess efficiency of electroporation and sonoporation methods by measuring distribution and accumulation of green fluorescence protein (GFP) concentration. 20 laboratory measurements were performed on mice to test the method.

The effect of ultrasound exposure on bleomycin fluorescence and pharmacological properties is studied. Bleomycin was treated by ultrasound for 7 min. Bleomycin fluorescence was measured during ultrasound exposure by means of fiber-optic spectrometry. Cell colony test was used to evaluate blemycin cytotoxity before and after ultrasound exposure.

Non-invasive and fast primary diagnostics of pigmented skin lesions is required due to frequent incidence of skin cancer - melanoma. Diagnostic potential of principal component analysis (PCA) for distant skin melanoma recognition is discussed. Processing of the measured clinical multi-spectral images (31 melanomas and 94 nonmalignant pigmented lesi...

Diagnostic potential of principal component analysis (PCA) of multi-spectral imaging data in the wavelength range 450-950 nm for distant skin melanoma recognition is discussed. Processing of the measured clinical data by means of PCA resulted in clear separation between malignant melanomas and pigmented nevi.

Laser speckle contrast analysis (LASCA) offers a non-contact, full-field, and real-time mapping of capillary blood flow and can be considered as an alternative method to Laser Doppler perfusion imaging (LDPI). Photoplethysmography (PPG) is well known technique for assessment of skin blood pulsations that can be related to blood flow. In recent year...

Possibilities to determine chromophore distribution in skin by spectral imaging were explored. Simple RGB sensor devices were used for image acquisition. Totally 200 images of 40 different bruises of 20 people were obtained in order to map chromophores bilirubin and haemoglobin. Possibilities to detect water in vitro and in vivo were estimated by u...

A prototype RGB imaging system for mapping of skin chromophores consists of a commercial RGB CMOS sensor, RGB LEDs ring-light illuminator and orthogonally orientated polarizers for reducing specular reflectance. The system was used for monitoring of vascular malformations (hemagiomas and telangiectasias) therapy.

Influence of low power laser irradiance on healthy skin using diffuse reflectance spectroscopy and multispectral imaging was studied. Changes of diffuse reflectance spectra in spectral range from 500 to 600 nm were observed after 405 nm, 473 nm and 532 nm laser provocation, leading to conclusion that the content of skin hemoglobin has changed. Peak...

There are a number of techniques for body composition assessment in clinics and in field-surveys, but in all cases the applied methods have advantages and disadvantages. High precision imaging methods are available, though expensive and non-portable, however, the methods devised for the mass population, often suffer from the lack of precision. Ther...

RGB imaging system for mapping and monitoring of hemoglobin changes in skin has been tested for evaluation of vascular malformations’ laser treatment. The multi-spectral imaging system was used as the reference.

Skin assessment technology based on comparative analysis of single-pixel RGB signal values at poly-chromatic illumination has been proposed. Multi-spectral imaging information from a single snapshot RGB image data set with the inter-channel crosstalk correction can be extracted this way. Proof-of-concept evaluations and measurement results are pres...

A prototype R-G-B imaging system for mapping of skin hemoglobin distribution has been designed and tested. Device basically consists of a commercial RGB sensor (CMOS, max. frame rate 87 fps for VGA resolution), RGB LED ringlight illuminator and orthogonally orientated polarizers for reducing specular reflectance. The system was examined for monitor...

Real-time non-contact photoplethysmography imaging (PPGI) system for high-resolution blood perfusion mapping in human skin has been proposed. The PPGI system comprises of LED lamp, webcam and computer with video processing software. The purpose of this study is to evaluate the reliability of the PPGI system when measuring blood perfusion. The valid...

An experimental RGB imaging system based on commercial color camera was constructed, and its potential for mapping of hemoglobin distribution in skin was studied. Two types of LEDs (RGB and white "warm" LEDs) were compared as illuminators for acquiring images of vascular and pigmented skin malformations. A novel approach for studies of skin capilla...

A clinical trial comprising 334 pigmented and vascular lesions has been performed in three Riga clinics by means of multispectral imaging analysis. The imaging system Nuance 2.4 (CRi) and self-developed software for mapping of the main skin chromophores were used. Specific features were observed and analyzed for malignant skin melanomas: notably hi...

Distant Determination of Bilirubin Distribution in Skin by Multi-Spectral Imaging For mapping the bilirubin distribution in bruised skin the multi-spectral imaging technique was employed, which made it possible to observe temporal changes of the bilirubin content in skin photo-types II and III. The obtained results confirm the clinical potential of...

A clinical trial comprising 266 pigmented lesions and 49 vascular lesions has been performed in three Riga clinics by means of multi-spectral imaging analysis. The imaging system Nuance 2.4 (CRI) and self-developed software for mapping of the main skin chromophores were used. The obtained results confirm clinical potential of this technology for no...

Impact of cw laser radiation on autofluorescence features of human skin is studied. Two methods of autofluorescence detection are applied: the spectral method with the use of a fibreoptic probe and spectrometer for determining the autofluorescence recovery kinetics at a fixed skin area of ~12 mm2, and the multispectral visualisation method with the...

The paper investigates influence and efficacy of laser therapy on pigmented and vascular cutaneous malformations by multispectral imaging technique. Parameter mapping of skin pigmented and vascular lesions and monitoring of the laser therapy efficacy are performed by multispectral imaging in wavelength range 450-700nm by scanning step - 10nm. Param...

In-vivo skin photo-bleaching (intensity decrease during irradiation) has been investigated at 405 nm cw laser excitation. Digital RGB photo-camera was used for studies of the bleaching features by analysis of fluorescent images at separated R, G and B spectral bands. Diagnostic potential based on correlations between skin pigmentation and bleaching...

The multi-spectral imaging technique has been used for distant mapping of in-vivo skin chromophores by analyzing spectral data at each reflected image pixel and constructing 2-D maps of the relative concentrations of oxy-/deoxyhemoglobin and melanin. Instead of using a broad visible-NIR spectral range, this study focuses on narrowed spectral band 5...

The multi-spectral imaging technique has been used for distant mapping of in-vivo skin chromophores by analyzing spectral data at each reflected image pixel and constructing 2-D maps of the relative concentrations of oxy-/deoxy-haemoglobin and melanin. Instead of using a broad visible-NIR spectral range, this study focuses on narrowed spectral band...

The possibilities to perform multi-band spectral imaging by means of a consumer color camera without external filters have been studied. Images at up to 6 spectral bands may be extracted from a single color image after appropriate signal processing. The proposed technique was tested in pilot measurements of in-vivo skin hemoglobin maps and laser-ex...

The multi-spectral imaging technique has been used for distant mapping of in-vivo skin haemoglobin. Besides, potential of selective R-G-B analysis of skin images has been studied under bi-chromatic (532 nm and 635 nm) laser illumination.