Hristo Nikolov

Investigation of the vertical profile of the aerosol scattering in the atmosphere by multichannel data from space station MIR

Abstract An approach is suggested and applied to determine the atmospheric optical depth parameters from spectral solar irradiance data provided by the multichannel trace spectrometric system “Spectrum 256”. The system “Spectrum 256” has been designed by scientists from the Solar-Terrestrial Influences Laboratory at the Bulgarian Academy of Sciences and has been operated onboard the MIR space station since 1988. By scanning the atmosphere with the spectrometer pointed directly at the Sun as the MIR station passed from the terminator zone to the sunset zone, the distribution of the atmospheric optical depth components in a vertical column of the Earths troposphere in the layer between 2 km and 14 km was determined. The molecular (Rayleigh) scattering was modeled and the aerosol scattering model parameters were evaluated. The selective absorption due to gaseous components and water vapor in the 475–810 nm spectral range was determined, taking into account the influence of the optical transmission characteristics of the hatches of the MIR station.

Remote sensing measurements in creating thematic spectral library

In Earth observations the reference spectra of well-described objects are required for better object-oriented interpretation of remotely sensed data from laboratory, field, airborne, and satellite sensors. For this purpose measurements of spectra using laboratory and field spectrometers are performed. The acquired spectra are used in creating a thematic spectral library. The used spectral instruments work in the wavelengths (0.4 to 2.5 microns) covering the spectral ranges from the visible /VIS/ to the shortwave infrared /SWIR/. Two different spectrometers are used to measure spectra included in the library: (1) Thematically oriented multichannel spectrometer covering the spectral range 0.4 to 0.9 microns and (2) high resolution NIRQuest spectrometer covering the range from 0.9 to 2.5 microns, both models of Ocean Optics Inc. Spectrometric measurements of representative samples of minerals, rocks, related soils, vegetation, and their natural mixtures are made in laboratory and field conditions. In some cases, samples were purified, so that the unique spectral characteristics of the studied objects could be related to their typical structure. The relations between the spectra and the structures are important for interpreting remotely sensed data acquired in the field or from an air- or space-borne platform. In some cases for making easy wide use of the spectra in the library the obtained spectra have to resample to selected broadband multispectral sensors for example those based on the satellites Landsat and Sentinel. The obtained spectral data with the metadata and additional information are planned for including in files for better interpretation of images with different spatial resolution.

Unmixing techniques for better segmentation of urban zones, roads, and open pit mines

In this paper the linear unmixing method has been applied in classification of manmade objects, namely urbanized zones, roads etc. The idea is to exploit to larger extent the possibilities offered by multispectral imagers having mid spatial resolution in this case TM/ETM+ instruments. In this research unmixing is used to find consistent regression dependencies between multispectral data and those gathered in-situ and airborne-based sensors. The correct identification of the mixed pixels is key element for the subsequent segmentation forming the shape of the artificial feature is determined much more reliable. This especially holds true for objects with relatively narrow structure for example two-lane roads for which the spatial resolution is larger that the object itself. We have combined ground spectrometry of asphalt, Landsat images of RoI, and in-situ measured asphalt in order to determine the narrow roads. The reflectance of paving stones made from granite is highest compared to another ones which is true for open and stone pits. The potential for mapping is not limited to the mid-spatial Landsat data, but also may be used if the data has higher spatial resolution (as fine as 0.5 m). In this research the spectral and directional reflection properties of asphalt and concrete surfaces compared to those of paving stone made from different rocks have been measured. The in-situ measurements, which plays key role have been obtained using the Thematically Oriented Multichannel Spectrometer (TOMS) - designed in STIL-BAS.

Data Acquisition Field Network in Support of Remote Sensing Investigations

Integrated use of data collected during remote sensing experiments and data from in-situ measurements reveal more features of the land cover objects under study. This features incorporated into existing GIS databases leads to better understanding, representing, managing, and integrating many aspects of the Earth as a complex system. The in-situ gathered data such as, ground control points by GPS, current meteorological conditions, soil moisture, etc., provides additional information that is crucial in improving GIS effectiveness in decision support. To improve and facilitate the process of collection and storage of in-situ data a distributed mobile, wireless, field network was developed. The main components of the system are the autonomous, battery-powered micro controller devices wirelessly communicating with a central one. In this paper short description of the technical parameters and communication protocols between devices, hubs and the control center is outlined. From topological point of view two types of networks can be implemented -simple, used in small areas (usually less than 10 km2) and full, covering areas up to 50 km2. Both networks has flexible structure, offered by a variable number of commands that could be easily adapted to meet the requirements of dissimilar measuring devices thus increasing the number of target applications -from land use to disaster monitoring. A prototype of the system successfully performed well on test polygons in North Bulgaria.

Interconnection architectures for transputer-based parallel image processing

Abstract Image processing has been undergoing rapid development for more than thirty years /1/, /2/. The tasks in this field are characterized by high computational complexity. Enabling image processing algorithms to run in real time requires large computational power. Modern display systems support more than 256 colors (8-bits) per pixel and typical images have a spatial resolution of 512×512 pixels or larger for each image. Supporting high resolution displays and imagery requires the use of visualization systems with high performance computational capabilities. The transputer is a contemporary state-of-the-art parallel computer environment that offers high computational performance at a relatively low price (i.e. high performance/price ratio) for building such systems. Our other goal is to prototype the use of transputers as a flexible image processing enginer for remote sensing applications.