The effect of seasonal variation on automated land cover mapping from multispectral airborne laser scanning data

Multispectral airborne laser scanning (MS-ALS) sensors are a new promising source of data for auto-mated mapping methods. Finding an optimal time for data acquisition is important in all mapping applica-tions based on remotely sensed datasets. In this study, three MS-ALS datasets acquired at different times of the growing season were compared for automated land cover mapping and road detection in a suburban area. In addition, changes in the intensity were studied. An object-based random forest classi-fication was carried out using reference points. The overall accuracy of the land cover classification was 93.9% (May dataset), 96.4% (June) and 95.9% (August). The use of the May dataset acquired under leafless conditions resulted in more complete roads than the other datasets acquired when trees were in leaf. It was concluded that all datasets used in the study are applicable for suburban land cover map-ping, however small differences in accuracies between land cover classes exist

TanDEM-X digital surface models in boreal forest above-ground biomass change detection

Satellite images provide spatially explicit information on forest change covering wide areas. In this study, bistatic TanDEM-X (TDX) synthetic aperture radar (SAR) satellite data were used to derive digital surface models (DSMs) of forest areas using SAR interferometry (InSAR). The capability of change features derived from bi-temporal InSAR DSMs to detect forest height (90th percen-tile of canopy height distribution, H90) and density variations was investigated. Moreover, changes in the forest above-ground bio-mass (AGB) were estimated from height changes between two In-SAR DSMs. Bi-temporal airborne laser scanning (ALS) data, aerial orthoimages and an ALS-based AGB change map from a study area in Southern Finland were used as references. The results indicate that the InSAR height change of a forested area correlates more with vegetation density change than with height change. The corre-lation between the InSAR mean height change and the height change feature from ALS was 0.76 at stand level. Correspondingly, the correlation between the InSAR mean height change and the ALS penetration rate change was 0.89. The AGB changes predicted based on InSAR height change agreed well with the reference data; the root-mean-square error (RMSE) was 20.7 Mg/ha (18.5% of the mean biomass in 2012) at stand level and 27.4 Mg/ha (27.0%) for 16 × 16 m grid cells. The results show that TDX DSMs can be used to detect biomass changes of different orders of magnitude, e.g. due to logging and thinning

Review on Active and Passive Remote Sensing Techniques for Road Extraction

Digital maps of road networks are a vital part of digital cities and intelligent transportation. In this paper, we provide a comprehensive review on road extraction based on various remote sensing data sources, including high-resolution images, hyperspectral images, synthetic aperture radar images, and light detection and ranging. This review is divided into three parts. Part 1 provides an overview of the existing data acquisition techniques for road extraction, including data acquisition methods, typical sensors, application status, and prospects. Part 2 underlines the main road extraction methods based on four data sources. In this section, road extraction methods based on different data sources are described and analysed in detail. Part 3 presents the combined application of multisource data for road extraction. Evidently, different data acquisition techniques have unique advantages, and the combination of multiple sources can improve the accuracy of road extraction. The main aim of this review is to provide a comprehensive reference for research on existing road extraction technologies.Peer reviewe

Toward utilizing multitemporal multispectral airborne laser scanning, Sentinel-2, and mobile laser scanning in map updating

The rapid development of remote sensing technologies pro-vides interesting possibilities for the further development of nationwide mapping procedures that are currently based mainly on passive aerial images. In particular, we assume that there is a large undiscovered potential in multitemporal airborne laser scanning (ALS) for topographic mapping. In this study, automated change detection from multitemporal multispectral ALS data was tested for the first time. The results showed that direct comparisons between height and intensity data from different dates reveal even small chang-es related to the development of a suburban area. A major challenge in future work is to link the changes with objects that are interesting in map production. In order to effectively utilize multisource remotely sensed data in mapping in the future, we also investigated the potential of satellite images and ground-based data to complement multispectral ALS. A method for continuous change monitoring from a time series of Sentinel-2 satellite images was developed and tested. Finally, a high-density point cloud was acquired with terres-trial mobile laser scanning and automatically classified into four classes. The results were compared with the ALS data, and the possible roles of the different data sources in a fu-ture map updating process were discussed

Genomförandeplan för rekommendationerna för utveckling av utbildningarna inom småbarnspedagogik

Utvecklingsforumet för utbildningarna inom småbarnspedagogik, som var verksamt 2019–2020, utredde nuläget för utbildningarna inom småbarnspedagogik och utarbetade ett program för utveckling av utbildningarna. I början av 2021 tillsattes det en expertgrupp för att fortsätta arbetet med utvecklingsprogrammets rekommendationer för utveckling av utbildningarna. Gruppens uppgift var att utarbeta en genomförandeplan som grundar sig på dessa rekommendationer. Expertgruppen överlämnade sitt förslag till genomförandeplan till undervisnings- och kulturministeriet i april 2021. Genomförandeplanen presenteras i den här publikationen. I planen redogörs det för sätt att genomföra utvecklingsrekommendationerna och anges också en ansvarig aktör/ansvariga aktörer och en tidsplan för varje föreslagen åtgärd. Dessutom innehåller planen förslag till mål, uppgifter, struktur, verksamhet och behövliga resurser för det nya Utvecklingsforumet för utbildningarna inom småbarnspedagogik som tillsätts 2021

Varhaiskasvatuksen koulutusten kehittämissuositusten toimeenpanosuunnitelma

Vuosina 2019–2020 toiminut Varhaiskasvatuksen koulutusten kehittämisfoorumi selvitti varhaiskasvatuksen koulutusten nykytilaa ja laati varhaiskasvatuksen koulutusten kehittämisohjelman. Kyseiseen kehittämisohjelmaan sisältyneiden koulutuksen kehittämissuositusten jatkotyöstämistä varten perustettiin alkuvuodesta 2021 asiantuntijatyöryhmä, jonka tehtävänä oli laatia näihin suosituksiin pohjautuva toimeenpanosuunnitelma. Asiantuntijaryhmä luovutti tässä julkaisussa esitellyn toimeenpanosuunnitelmaehdotuksensa opetus- ja kulttuuriministeriölle huhtikuussa 2021. Toimeenpanosuunnitelmassa eritellään kehittämissuositusten toteuttamisen tavat, esitetään kunkin toimenpide-ehdotuksen kohdalla sen toteuttamisen vastuutaho/vastuutahot ja tavoiteltava aikataulu. Lisäksi tehdään ehdotus myöhemmin vuonna 2021 asetettavan uuden Varhaiskasvatuksen koulutusten kehittämisfoorumin tavoitteista, tehtävistä, rakenteesta, toiminnasta ja tarvittavista resursseista

Airborne Laser Scanning Outperforms the Alternative 3D Techniques in Capturing Variation in Tree Height and Forest Density in Southern Boreal Forests

The objective of this study is to better understand the relationship between forest structure and point cloud features generated from certain airborne and space borne sensors. Point cloud features derived from airborne laser scanning (ALS), aerial imagery (AI), WorldView-2 imagery (WV2), TerraSAR-X, and Tandem-X (TDX) data were classified as features characterizing forest height and density as well as variation in tree height. Correlations between these features and field-measured attributes describing forest height, density and tree height variation were investigated at plot scale. From the field-measured attributes, basal area (G) and the number of trees per unit area (N) were used as forest density indicators whereas maximum tree height (H-max) and standard deviation in tree height (H-std) were used as indicators for forest height and tree height variation, respectively. In the analyses, field observations from 91 sample plots (32 m x 32 m) located in southern Finland were used. Even though ALS was found to be the most accurate data source in characterizing forest structure, AI, WV2, and TDX were also capable of characterizing forest height at plot scale with correlation coefficients stronger than 0.85. However, ALS was the only data source capable of providing separate features for characterizing also the variation in tree height and forest density. Features related to forest height, generated from the other data sources besides ALS, also provided strongest correlation with the forest density attributes and variation in tree height, in addition to H-max. Due to these more diverse characterization capabilities, forest structural attributes can be predicted more accurately by using ALS, also in the areas where the relation between the attributes of interest is not solely dependent on forest height, compared to the other investigated 3D remote sensing data sources.Peer reviewe

Airborne laser scanning outperforms the alternative 3D techniques in capturing variation in tree height and forest density in southern boreal forests.

ArticleBaltic Forestry. 24(2): 268-277. (2018)journal articl

Monitoring Changes in Rice Cultivated Area from SAR and Optical Satellite Images in Ben Tre and Tra Vinh Provinces in Mekong Delta, Vietnam

The objective of this study was to obtain up-to-date information on land use and to identify long term changes in land use, especially rice, aquaculture and other crops in Ben Tre and Tra Vinh provinces in Vietnam’s Mekong Delta. Long-term changes in land-use of the study area have not been studied using long time series of SAR and optical Earth observation (EO) data before. EO data from 1979–2012 was used: ENVISAT ASAR Wide Swath Mode, SPOT and Landsat imagery. An unsupervised ISODATA classification was performed on multitemporal SAR images. The results were validated using ground truth data. Using the Synthetic Aperture Radar (SAR) imagery maps for 2005, 2009 and 2011 were obtained. Different rice crops, aquaculture and fruit trees could be distinguished with an overall accuracy of 80%. Using available optical imagery the time series was extended from 2005 to 1979. Long-term decrease in the rice acreage and increase in the aquaculture acreage could be detected