39,365 research outputs found
Discriminating small wooded elements in rural landscape from aerial photography: a hybrid pixel/object-based analysis approach
While small, fragmented wooded elements do not represent a large surface area in
agricultural landscape, their role in the sustainability of ecological processes is
recognized widely. Unfortunately, landscape ecology studies suffer from the lack
of methods for automatic detection of these elements. We propose a hybrid
approach using both aerial photographs and ancillary data of coarser resolution
to automatically discriminate small wooded elements. First, a spectral and textural
analysis is performed to identify all the planted-tree areas in the digital photograph.
Secondly, an object-orientated spatial analysis using the two data sources
and including a multi-resolution segmentation is applied to distinguish between
large and small woods, copses, hedgerows and scattered trees. The results show the
usefulness of the hybrid approach and the prospects for future ecological
applications
Urban detection, delimitation and morphology: comparative analysis of selective "megacities"
Postprint (published version
Relating visual and semantic image descriptors
This paper addresses the automatic analysis of visual content and extraction of metadata beyond pure visual descriptors. Two approaches are described: Automatic Image Annotation (AIA) and Confidence Clustering (CC). AIA attempts to automatically classify images based on two binary classifiers and is
designed for the consumer electronics domain. Contrastingly, the CC approach does not attempt to assign a unique label to images but rather to organise the database based on concepts
The visual preferences for forest regeneration and field afforestation : four case studies in Finland
The overall aim of this dissertation was to study the public's preferences for forest regeneration fellings and field afforestations, as well as to find out the relations of these preferences to landscape management instructions, to ecological healthiness, and to the contemporary theories for predicting landscape preferences. This dissertation includes four case studies in Finland, each based on the visualization of management options and surveys.
Guidelines for improving the visual quality of forest regeneration and field afforestation are given based on the case studies. The results show that forest regeneration can be connected to positive images and memories when the regeneration area is small and some time has passed since the felling. Preferences may not depend only on the management alternative itself but also on the viewing distance, viewing point, and the scene in which the management options are implemented.
The current Finnish forest landscape management guidelines as well as the ecological healthiness of the studied options are to a large extent compatible with the public's preferences. However, there are some discrepancies. For example, the landscape management instructions as well as ecological hypotheses suggest that the retention trees need to be left in groups, whereas people usually prefer individually located retention trees to those trees in groups. Information and psycho-evolutionary theories provide some possible explanations for people's preferences for forest regeneration and field afforestation, but the results cannot be consistently explained by these theories.
The preferences of the different stakeholder groups were very similar. However, the preference ratings of the groups that make their living from forest - forest owners and forest professionals - slightly differed from those of the others. These results provide support for the assumptions that preferences are largely consistent at least within one nation, but that knowledge and a reference group may also influence preferences.VÀitöskirjassa tutkittiin ihmisten maisemapreferenssejÀ (maisemallisia arvostuksia) metsÀnuudistamishakkuiden ja pellonmetsitysten suhteen sekÀ analysoitiin nÀiden preferenssien yhteyksiÀ maisemanhoito-ohjeisiin, vaihtoehtojen ekologiseen terveyteen ja preferenssejÀ ennustaviin teorioihin. VÀitöskirja sisÀltÀÀ neljÀ tapaustutkimusta, jotka perustuvat hoitovaihtoehtojen visualisointiin ja kyselytutkimuksiin.
Tapaustutkimusten pohjalta annetaan ohjeita siitÀ, kuinka uudistushakkuiden ja pellonmetsitysten visuaalista laatua voidaan parantaa. VÀitöskirjan tulokset osoittavat, ettÀ uudistamishakkuut voivat herÀttÀÀ myös myönteisiÀ mielikuvia ja muistoja, jos uudistusala on pieni ja hakkuun vÀlittömÀt jÀljet ovat jo peittyneet. Preferensseihin vaikuttaa hoitovaihtoehdon lisÀksi mm. katseluetÀisyys, katselupiste ja ympÀristö, jossa vaihtoehto on toteutettu.
Eri viiteryhmien (metsÀammattilaiset, pÀÀkaupunkiseudun asukkaat, ympÀristönsuojelijat, tutkimusalueiden matkailijat, paikalliset asukkaat sekÀ metsÀnomistajat) maisemapreferenssit olivat hyvin samankaltaisia. Kuitenkin ne ryhmÀt, jotka saavat ainakin osan elannostaan metsÀstÀ - metsÀnomistajat ja metsÀammattilaiset - pitivÀt metsÀnhakkuita esittÀvistÀ kuvista hieman enemmÀn kuin muut ryhmÀt. NÀmÀ tulokset tukevat oletusta, ettÀ maisemapreferenssit ovat laajalti yhtenevÀisiÀ ainakin yhden kansan tai kulttuurin keskuudessa, vaikka myös viiteryhmÀ saattaa vaikuttaa preferensseihin jonkin verran.
Nykyiset metsÀmaisemanhoito-ohjeet ovat pitkÀlti samankaltaisia tÀssÀ vÀitöskirjassa havaittujen maisemapreferenssien kanssa. MyöskÀÀn tutkittujen vaihtoehtoisten hoitotapojen ekologisen paremmuuden ja niihin kohdistuvien maisemallisten arvostusten vÀlillÀ ei ollut suurta ristiriitaa. Kuitenkin joitakin eroavaisuuksia oli; esimerkiksi sekÀ maisemanhoito-ohjeiden ettÀ ekologisten hypoteesien mukaan sÀÀstöpuut tulisi jÀttÀÀ ryhmiin, kun taas ihmiset pitivÀt eniten yksittÀin jÀtetyistÀ puista. Informaatiomalli ja psyko-evolutionaarinen teoria tarjoavat mahdollisia selityksiÀ uudistushakkuisiin ja pellonmetsitykseen kohdistuville preferensseille, vaikkakaan tutkimuksen tuloksia ei voida tÀysin selittÀÀ nÀillÀ teorioilla
Hybrid image representation methods for automatic image annotation: a survey
In most automatic image annotation systems, images are represented with low level features using either global
methods or local methods. In global methods, the entire image is used as a unit. Local methods divide images into blocks where fixed-size sub-image blocks are adopted as sub-units; or into regions by using segmented regions as sub-units in images. In contrast to typical automatic image annotation methods that use either global or local features exclusively, several recent methods have considered incorporating the two kinds of information, and believe that the combination of the two levels of features is
beneficial in annotating images. In this paper, we provide a
survey on automatic image annotation techniques according to
one aspect: feature extraction, and, in order to complement
existing surveys in literature, we focus on the emerging image annotation methods: hybrid methods that combine both global and local features for image representation
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