Hitra urbanizacija ima številne negativne vplive na okolje in zdravje ljudi ter pomembno prispeva h globalnemu segrevanju. Eden izmed teh vplivov so tudi mestni toplotni otoki, ki jih povzroca ...clovekova dejavnost in so opredeljeni kot temperaturne razlike med mestnimi in okoliškimi obmocji. Zaradi hitre urbanizacije v zadnjih desetletjih se Skopje spoprijema z izjemno mocnimi ucinki mestnih toplotnih otokov. Za proucevanje vloge pozidanih in zelenih površin pri nastanku površinskega mestnega toplotnega otoka je avtorica uporabila satelitske podatke Landsat ETM+, na podlagi katerih je analizirala temperaturo tal, in posnetke satelita Planet Scope DOVE visoke locljivosti, na podlagi katerih je analizirala pozidane in zelene površine. Za geostatisticne analize je uporabila 17 nakljucno izbranih podobmocij v Skopju. Izsledki raziskave kažejo pomembno povezavo med mestnim toplotnim otokom in pozidanimi površinami ter mocno povezavo med zelenimi površinami in obmocji, na katerih ni mestnega toplotnega otoka, kar kaže, da se lahko ucinek mestnih toplotnih otokov pomembno zmanjša z dodatnimi zelenimi površinami. Eden izmed pomembnih izsledkov raziskave je, da idealno razmerje med deležem pozidanih in zelenih površin, pri katerem je ucinek mestnega toplotnega otoka šibek, v nekaterih primerih pa ga celo ni, znaša 40 : 60. Nadaljnje raziskave bi se morale osredotocati še na druge dejavnike, ki lahko vplivajo na nastanek mestnega toplotnega otoka.
The monograph presents a fully automated procedure for geometric correction of optical satellite images, without any manual intervention during the processing. The resulting orthorectified image is ...in the national coordinate system and constitutes a suitable source for spatial analyses. In the monograph the original procedure connects several different methods into a single, robust system for automatic generation of orthoimages is documented in detail. The work describes the whole automatic orthorectification process, which comprises four basic modules: a module for extracting and preparing the metadata, a module for automatic extraction of ground control points, a module for calculation of parameters of the geometric model, and a module for orthorectification. The experiments and results with RapidEye and WorldView-2 images are also presented. The experiments evaluate the procedure for automatic extraction of points, the geometric model, the elimination of gross errors, and the positional accuracy of the orthoimages. The analisys of the results indicate that the automated procedure produces orthoimages with a positional accuracy of about two pixels or better, even if several gross errors are present among the automatically extracted ground control points.
V prispevku je obravnavana uporabnost postopkov strojnega učenja pri ugotavljanju poplavljenih območij v zgornjem delu Selške doline, ki jo je 18. 9. 2007 prizadelo hudourniško deževje. Hitro ...prepoznavanje poplavljenih območij je ključnega pomena za učinkovito reševanje in povračilo škode od zavarovalnic. Pri tem so zelo uporabni satelitskiposnetki, saj omogočajo hitro določitev poplavljenih območij, tudi če so prizadeti zelo veliki predeli. Za prepoznavanje poplavljenih območij v Selški dolini so bile uporabljene tehnike strojnega učenja zrazličnimi vhodnimi podatki: satelitski posnetek SPOT (multispektralni in pankromatski), indeks NDVI, relief in njegovi izdelki (nadmorska višina, naklon, ukrivljenost), oddaljenost od vodotokov in raba tal. Učni vzorci, ki so bili uporabljeni za oblikovanje modela klasifikacije, so vsebovali 400, 255 oziroma49 vzorčnih točk. : This paper discusses the usefulness of machinelearning procedures for determining flooded areas in the upper part of the Selška valley. The area was affected by torrential rains on 18.9.2007. Rapid identification of flooded areas is essential for effective implementation of rescue operations and damage assessments. In this case, satellite images are very useful because they enable quick identification of flooded areas even in very large areas. To determine the flooded areas, machine learning techniques were applied to different input data. SPOT satellite image (multispectral and panchromatic), NDVI index, relief and its derivatives (altitude, slope, curvature), distance from rivers and land use were used. The learning samples consisted of 400, 255 and 49 sample points, which were used to build three different classification models.
An application of data mining for the determination of flooded areas was published in the Journal Geodetski vestnik (no. 54/2010-4). This paper analyses the usefulness of these results for further ...analyses of hydraulic parameters. The velocity and discharges were computed for six locations. The study showed that the flooded areas determined by satellite images can be used for further analyses. Nevertheless, other layers have to be sufficiently precise, especially the digital terrain model (DTM). DTM 12.5 was used. The study showed that DTM 12.5 is not precise enough. The observed area is very rough and the hydraulic parameters (cross sectional area of flow, wetted perimeter, hydraulic radius, river-bottom slope, flow velocity, discharge) cannot be detected with sufficient precision. Consequently, the calculated hydraulic radiuses, velocities and discharges are out of expectations. In the first part of the article, some basic information about remote sensing and its techniques is presented. Some practical examples of their usage (especially satellite images) for the observation of natural disasters are also given.
V članku je opisana izdelava digitalnega model površja (DMP) in ortopodob iz pankromatskega in multispektralnega stereopara posnetkov Ikonos. Pri tem se ugotavlja primernost posnetkov za ...kartiranjevišine vegetacije večjega območja in uporabnost rezultatov za namene različnih prostorskih analiz. Koraki obdelave so vključevali izravnavo posnetkov s snopi z različnimi razporeditvami in številomoslonilnih točk, izdelavo digitalnega modela površja in ortopodob ter vrednotenje rezultatov. DMP je bil zaradi boljše ločljivosti posnetkov izdelan samo iz pankromatskega stereopara. Rezultati so bilivrednoteni s primerjavo z zelo natančnim modelom površja, izdelanim iz lidarskih podatkov. Analize so pokazale, da je povprečna višinska razlika med modeloma 8,2 metra, pri čemer je samo tretjinarazlik manjših od 3 metrov. Rezultati so bili slabši na strmih pobočjih z visoko vegetacijo in območjih s sencami, ki so jih povzročili hribi in oblaki. Po drugi strani so bili rezultati vrednotenja ortopodob z ortofoto posnetki veliko boljši, saj so RMSE (koren povprečne kvadratne napake) položaja znašali pod 1,5 piksla zaoba uporabljena stereopara. ; The paper describes the generation of a digital surface model (DSM) and orthoimages from panchromaticand multispectral Ikonos stereopairs. It assesses the suitability of the images for vegetation height mapping of a large area and the applicability of the results for various spatial analyses. The processing steps involved stereo bundle adjustment with varioussets of ground control points, digital surface model extraction, orthoimage generation and evaluation of the results. Although both multispectral and panchromatic stereoimages were processed, the DSMwas generated only for the panchromatic stereopair due to its higher resolution. For evaluation purposes it was compared to very accurate lidar elevation data. The analysis revealed an overall vertical difference between the models of 8.2 m, where only one thirdof the differences are below 3 m. The results were worse in steep areas with high vegetation and regions with shadows caused by hills or clouds. Better results can be obtained with previous manual or automatic editing of the automatically extracted model. On theother side, orthoimages that were also produced are very accurate – the evaluation showed results with horizontal RMSE errors below 1.5 pixels for both stereopairs when compared to aerial orthophotos
V članku je opisana izdelava digitalnega model površja (DMP) in ortopodob iz pankromatskega in multispektralnega stereopara posnetkov Ikonos. Pri tem se ugotavlja primernost posnetkov za ...kartiranjevišine vegetacije večjega območja in uporabnost rezultatov za namene različnih prostorskih analiz. Koraki obdelave so vključevali izravnavo posnetkov s snopi z različnimi razporeditvami in številomoslonilnih točk, izdelavo digitalnega modela površja in ortopodob ter vrednotenje rezultatov. DMP je bil zaradi boljše ločljivosti posnetkov izdelan samo iz pankromatskega stereopara. Rezultati so bilivrednoteni s primerjavo z zelo natančnim modelom površja, izdelanim iz lidarskih podatkov. Analize so pokazale, da je povprečna višinska razlika med modeloma 8,2 metra, pri čemer je samo tretjinarazlik manjših od 3 metrov. Rezultati so bili slabši na strmih pobočjih z visoko vegetacijo in območjih s sencami, ki so jih povzročili hribi in oblaki. Po drugi strani so bili rezultati vrednotenja ortopodob z ortofoto posnetki veliko boljši, saj so RMSE (koren povprečne kvadratne napake) položaja znašali pod 1,5 piksla zaoba uporabljena stereopara.The paper describes the generation of a digital surface model (DSM) and orthoimages from panchromaticand multispectral Ikonos stereopairs. It assesses the suitability of the images for vegetation height mapping of a large area and the applicability of the results for various spatial analyses. The processing steps involved stereo bundle adjustment with varioussets of ground control points, digital surface model extraction, orthoimage generation and evaluation of the results. Although both multispectral and panchromatic stereoimages were processed, the DSMwas generated only for the panchromatic stereopair due to its higher resolution. For evaluation purposes it was compared to very accurate lidar elevation data. The analysis revealed an overall vertical difference between the models of 8.2 m, where only one thirdof the differences are below 3 m. The results were worse in steep areas with high vegetation and regions with shadows caused by hills or clouds. Better results can be obtained with previous manual or automatic editing of the automatically extracted model. On theother side, orthoimages that were also produced are very accurate – the evaluation showed results with horizontal RMSE errors below 1.5 pixels for both stereopairs when compared to aerial orthophotos.
In the article, the application of stereopairs of panchromatic and multispectral SPOT satellite imagery in photogrammetric applications is presented. Theoretical basis of the generation of digital ...elevation models and orthoimages and a description of the practical processing of orthoimages are given. Examined are the possibilities of the application of the middle-resolution images from mountainousregions. The accuracy of the orthoimages has been determined by comparing with orthophotos DOF 5. The results are unexpectedly good and show the potential of SPOT imagery. The accuracy of the resultshas been, in addition to the input data, affected by the restrictions of the digital, automatic processing techniques in the software applied.
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