Digital Photography in the Diagnosis and Follow-up of Ocular Diseases

Purpose: The aim of the present study was to develop and test new digital imaging equipment and methods for diagnosis and follow-up of ocular diseases. Methods: The whole material comprised 398 subjects (469 examined eyes), including 241 patients with melanocytic choroidal tumours, 56 patients with melanocytic iris tumours, 42 patients with diabetes, a 52-year old patient with chronic phase of VKH disease, a 30-year old patient with an old blunt eye injury, and 57 normal healthy subjects. Digital 50° (Topcon TRC 50 IA) and 45° (Canon CR6-45NM) fundus cameras, a new handheld digital colour videocamera for eye examinations (MediTell), a new subtraction method using the Topcon Image Net Program (Topcon corporation, Tokyo, Japan), a new method for digital IRT imaging of the iris we developed, and Zeiss photoslitlamp with a digital camera body were used for digital imaging. Results: Digital 50° red-free imaging had a sensitivity of 97.7% and two-field 45° and 50° colour imaging a sensitivity of 88.9-94%. The specificity of the digital 45°-50° imaging modalities was 98.9-100% versus the reference standard and ungradeable images that were 1.2-1.6%. By using the handheld digital colour video camera only, the optic disc and central fundus located inside 20° from the fovea could be recorded with a sensitivity of 6.9% for detection of at least mild NPDR when compared with the reference standard. Comparative use of digital colour, red-free, and red light imaging showed 85.7% sensitivity, 99% specificity, and 98.2 % exact agreement versus the reference standard in differentiation of small choroidal melanoma from pseudomelanoma. The new subtraction method showed growth in four of 94 melanocytic tumours (4.3%) during a mean ±SD follow-up of 23 ± 11 months. The new digital IRT imaging of the iris showed the sphincter muscle and radial contraction folds of Schwalbe in the pupillary zone and radial structural folds of Schwalbe and circular contraction furrows in the ciliary zone of the iris. The 52-year-old patient with a chronic phase of VKH disease showed extensive atrophy and occasional pigment clumps in the iris stroma, detachment of the ciliary body with severe ocular hypotony, and shallow retinal detachment of the posterior pole in both eyes. Infrared transillumination imaging and fluorescein angiographic findings of the iris showed that IR translucence (p=0.53), complete masking of fluorescence (p=0.69), presence of disorganized vessels (p=0.32), and fluorescein leakage (p=1.0) at the site of the lesion did not differentiate an iris nevus from a melanoma. Conclusions: Digital 50° red-free and two-field 50° or 45° colour imaging were suitable for DR screening, whereas the handheld digital video camera did not fulfill the needs of DR screening. Comparative use of digital colour, red-free and red light imaging was a suitable method in the differentiation of small choroidal melanoma from different pseudomelanomas. The subtraction method may reveal early growth of the melanocytic choroidal tumours. Digital IRT imaging may be used to study changes of the stroma and posterior surface of the iris in various diseases of the uvea. It contributed to the revealment of iris atrophy and serous detachment of the ciliary body with ocular hypotony together with the shallow retinal detachment of the posterior pole as new findings of the chronic phase of VKH disease. Infrared translucence and angiographic findings are useful in differential diagnosis of melanocytic iris tumours, but they cannot be used to determine if the lesion is benign or malignant.

Shooting from the Wild Zone : A Study of the Chicana Art Photographers Laura Aguilar, Celia Álvarez Muñoz, Delilah Montoya, and Kathy Vargas

The dissertation analyzes and elaborates upon the changing map of U.S. ethno-racial formation from the vantage point of North American Studies, multi-disciplinary cultural studies, and the criticism of visual culture. The focus is on four contemporary Mexican American (Chicana) women photographers, whose art production is discussed, on the one hand, in the context of the Euro-American history of photographic genres and, on the other hand, in the context of so-called decolonizing cultural and academic discourses produced by Mexican Americans themselves. The manuscript consists of two parts. Part I outlines the theoretical and methodological domain of the study, positioning it in the interstices of American studies, European postmodern criticism, postcolonial feminist theory, and the theories of visual culture, particularly of art photography. In addition, the main issues and paradigms of Chicano Studies (Mexican American ethnic studies) are introduced. Part II consists of seven essays, each of which discusses rather independently a particular photographic work or a series of photographs, formulating and defending arguments about their meaning, position in the history of photographic genres, and their cultural and socio-political significance. The study closes with a discussion about ethno-racial identity formation and the role of Chicana photography therein - in embodying and reproducing new subjectivities, alternative categories of knowledge, and open ended historical narratives. It is argued that, symbolically, the "Wild Zone" of gendered and race-specific knowledge becomes associated with the body of the mother, a recurrent image in Chicana art works under discussion. Embedded in this image, the construction of an alternative notion of a family thus articulates the parameters of a matrifocal ethno-racial community unified by the proliferation of differences rather than by conformities typical of nationalistic ideologies. While focusing on art photography, the study as a whole simultaneously constructs, from a European vantage point, a "thick" description of Mexican American history, identities, communities, cultural practices, and self-representations about which very little is known in Finland.

La modernización entre cafetales : San José, Costa Rica, 1880-1930

This work examines the urban modernization of San José, Costa Rica, between 1880 and 1930, using a cultural approach to trace the emergence of the bourgeois city in a small Central American capital, within the context of order and progress. As proposed by Henri Lefebvre, Manuel Castells and Edward Soja, space is given its rightful place as protagonist. The city, subject of this study, is explored as a seat of social power and as the embodiment of a cultural transformation that took shape in that space, a transformation spearheaded by the dominant social group, the Liberal elite. An analysis of the product built environment allows us to understand why the city grew in a determined manner: how the urban space became organized and how its infrastructure and services distributed. Although the emphasis is on the Liberal heyday from 1880-1930, this study also examines the history of the city since its origins in the late colonial period through its consolidation as a capital during the independent era, in order to characterize the nineteenth century colonial city that prevailed up to 1890 s. A diverse array of primary sources including official acts, memoirs, newspaper sources, maps and plans, photographs, and travelogues are used to study the initial phase of San Jose s urban growth. The investigation places the first period of modern urban growth at the turn of the nineteenth century within the prevailing ideological and political context of Positivism and Liberalism. The ideas of the city s elite regarding progress were translated into and reflected in the physical transformation of the city and in the social construction of space. Not only the transformations but also the limits and contradictions of the process of urban change are examined. At the same time, the reorganization of the city s physical space and the beginnings of the ensanche are studied. Hygiene as an engine of urban renovation is explored by studying the period s new public infrastructure (including pipelines, sewer systems, and the use of asphalt pavement) as part of the Saneamiento of San José. The modernization of public space is analyzed through a study of the first parks, boulevards and monuments and the emergence of a new urban culture prominently displayed in these green spaces. Parks and boulevards were new public and secular places of power within the modern city, used by the elite to display and educate the urban population into the new civic and secular traditions. The study goes on to explore the idealized image of the modern city through an analysis of European and North American travelogues and photography. The new esthetic of theatrical-spectacular representation of the modern city constructed a visual guide of how to understand and come to know the city. A partial and selective image of generalized urban change presented only the bourgeois facade and excluded everything that challenged the idea of progress. The enduring patterns of spatial and symbolic exclusion built into Costa Rica s capital city at the dawn of the twentieth century shed important light on the long-term political social and cultural processes that have created the troubled urban landscapes of contemporary Latin America.

Ajan sisäkkäiset tilat. Arkkitehtuuri, valokuva ja menneisyyden esittäminen W. G. Sebaldin romaanissa Austerlitz

In her thesis, Kaisa Kaakinen analyzes how the German emigrant author W. G. Sebald (1944-2001) uses architecture and photography in his last novel "Austerlitz" to represent time, history and remembering. Sebald describes time in spatial terms: it is like a building, the rooms and chambers of which are connected to each other. The poetics of spatial time manifests itself on multiple levels of the text. Kaakinen traces it in architectural representations, photographic images, intertextuality, as well as in the form of the text, using the concept of spatial form by Joseph Frank. Architectural and photographic representations serve as meeting points for different aspects and angles of the novel and illustrate the idea of a layered present that has multiple connections to the past. The novel tells a story of Jacques Austerlitz, who as a small child was sent from Prague to Britain in one of the so-called Kindertransports that saved children from Central Europe occupied by the National Socialists. Only gradually he remembers his Jewish parents, who have most likely perished in Nazi concentration camps. The novel brings the problematic of writing about another person's past to the fore by the fact that Austerlitz's story is told by an anonymous narrator, Austerlitz's interlocutor, who listens to and writes down Austerlitz's story. Kaakinen devotes the final part of her thesis to study the demands of representing a historical trauma, drawing on authors such as Dominick LaCapra and Michael Rothberg. Through the analysis of architectural and photographic representations in the novel, she demonstrates how Austerlitz highlights the sense of singularity and inaccessibility of memories of an individual, while also stressing the necessity - and therefore a certain kind of possibility - of passing these memories to another person. The coexistence of traumatic narrowness and of the infinity of history is reflected in ambivalent buildings. Some buildings in the novel resemble reversible figures: they can be perceived simultaneously as ruins and as construction sites. Buildings are also shown to be able to both cover and preserve memories - an idea that also is repeated in the use of photography, which tends to both replace memories and cause an experience of the presence of an absent thing. Commenting and critisizing some recent studies on Sebald, the author develops a reading which stresses the ambivalence inherent in Sebald's view on history and historiography. Austerlitz shows the need to recognize the inevitable absence of the past as well as the distance from the experiences of others. Equally important, however, is the refusal to give up narrating the past: Sebald's novel stresses the necessity to preserve the sites of the past, which carry silent traces of vanished life. The poetics of Austerlitz reflects the paradox of the simultaneous impossibility and indispensability of writing history.

Kuvan ja tekstin välissä : Kuvateksti uutiskuvan ja lehtijutun elementtinä

The study focuses on picture captions: their grammar and interplay with photographs and their position as semi-independent elements of the news stories. The research was conducted in the framework of critical discourse analysis, social semiotic visual theory and fennistic syntactical research. The data consist of 441 press photographs, 1,815 captions and a number of news items from Finnish dailies. The generic structure potential of the caption includes the caption headline, the caption proper, i.e. the verbalization of the picture content, and the frame. In the data, 41 per cent of the captions have a headline, and 44 per cent contain a caption proper. Characteristic of the caption proper is omission of the finite verb and the use of the present tense, both of which have decreased in Finnish papers during the 20th century. The caption proper is typically a main clause, and both subordinate clauses and participal phrases occur mostly in the frame. While comparing caption variants attached to the same pictures, the processes and their participants proved to be identified considerably identically, following the news agency captions. Instead, the reader?s interpretations of a picture could be directed by framing it in different ways. For example, the caption may focus on the only person depicted, deal with a whole group, or give an abstract account of the situation. The caption is a paratext, a typographically marked, semi-independent element of a news story. Between the headline and the caption, four semantic relations have been identified. The caption may be a paraphrase of the headline, or a close-up illustrating an abstract headline with a concrete example. If the name of the person depicted is their only common factor, the relation between the caption and the headline is additive. A specifying caption will give more details than the headline. The caption may complete, repeat, or summarize the body copy. Naturally, most captions completing the story verbalize the content of the picture. As the caption is often based on the story, it may even repeat the body copy verbatim. The summarizing function is probably becoming increasingly important, as most Finnish newspapers have abandoned the use of a separate standfirst.

Multiangular Spectrometry and Optical Properties of Debris Covered Surfaces

Due to the recent development in CCD technology aerial photography is now slowly changing from film to digital cameras. This new aspect in remote sensing allows and requires also new automated analysis methods. Basic research on reflectance properties of natural targets is needed so that computerized processes could be fully utilized. For this reason an instrument was developed at Finnish Geodetic Institute for measurement of multiangular reflectance of small remote sensing targets e.g. forest understorey or asphalt. Finnish Geodetic Institute Field Goniospectrometer (FiGIFiGo) is a portable device that is operated by 1 or 2 persons. It can be reassembled to a new location in 15 minutes and after that a target's multiangular reflectance can be measured in 10 - 30 minutes (with one illumination angle). FiGIFiGo has effective spectral range approximately from 400 nm to 2000 nm. The measurements can be made either outside with sunlight or in laboratory with 1000 W QTH light source. In this thesis FiGIFiGo is introduced and the theoretical basis of such reflectance measurements are discussed. A new method is introduced for extraction of subcomponent proportions from reflectance of a mixture sample, e.g. for retrieving proportion of lingonberry's reflectance in observation of lingonberry-lichen sample. This method was tested by conducting a series of measurements on reflectance properties of artificial samples. The component separation method yielded sound results and brought up interesting aspects in targets' reflectances. The method and the results still need to be verified with further studies, but the preliminary results imply that this method could be a valuable tool in analysis of such mixture samples.

Remote sensing of leaf area index: enhanced retrieval from close-range and remotely sensed optical observations

A wide range of models used in agriculture, ecology, carbon cycling, climate and other related studies require information on the amount of leaf material present in a given environment to correctly represent radiation, heat, momentum, water, and various gas exchanges with the overlying atmosphere or the underlying soil. Leaf area index (LAI) thus often features as a critical land surface variable in parameterisations of global and regional climate models, e.g., radiation uptake, precipitation interception, energy conversion, gas exchange and momentum, as all areas are substantially determined by the vegetation surface. Optical wavelengths of remote sensing are the common electromagnetic regions used for LAI estimations and generally for vegetation studies. The main purpose of this dissertation was to enhance the determination of LAI using close-range remote sensing (hemispherical photography), airborne remote sensing (high resolution colour and colour infrared imagery), and satellite remote sensing (high resolution SPOT 5 HRG imagery) optical observations. The commonly used light extinction models are applied at all levels of optical observations. For the sake of comparative analysis, LAI was further determined using statistical relationships between spectral vegetation index (SVI) and ground based LAI. The study areas of this dissertation focus on two regions, one located in Taita Hills, South-East Kenya characterised by tropical cloud forest and exotic plantations, and the other in Gatineau Park, Southern Quebec, Canada dominated by temperate hardwood forest. The sampling procedure of sky map of gap fraction and size from hemispherical photographs was proven to be one of the most crucial steps in the accurate determination of LAI. LAI and clumping index estimates were significantly affected by the variation of the size of sky segments for given zenith angle ranges. On sloping ground, gap fraction and size distributions present strong upslope/downslope asymmetry of foliage elements, and thus the correction and the sensitivity analysis for both LAI and clumping index computations were demonstrated. Several SVIs can be used for LAI mapping using empirical regression analysis provided that the sensitivities of SVIs at varying ranges of LAI are large enough. Large scale LAI inversion algorithms were demonstrated and were proven to be a considerably efficient alternative approach for LAI mapping. LAI can be estimated nonparametrically from the information contained solely in the remotely sensed dataset given that the upper-end (saturated SVI) value is accurately determined. However, further study is still required to devise a methodology as well as instrumentation to retrieve on-ground green leaf area index . Subsequently, the large scale LAI inversion algorithms presented in this work can be precisely validated. Finally, based on literature review and this dissertation, potential future research prospects and directions were recommended.

Geospatial environmental data modelling applications using remote sensing, GIS and spatial statistics

This thesis presents novel modelling applications for environmental geospatial data using remote sensing, GIS and statistical modelling techniques. The studied themes can be classified into four main themes: (i) to develop advanced geospatial databases. Paper (I) demonstrates the creation of a geospatial database for the Glanville fritillary butterfly (Melitaea cinxia) in the Åland Islands, south-western Finland; (ii) to analyse species diversity and distribution using GIS techniques. Paper (II) presents a diversity and geographical distribution analysis for Scopulini moths at a world-wide scale; (iii) to study spatiotemporal forest cover change. Paper (III) presents a study of exotic and indigenous tree cover change detection in Taita Hills Kenya using airborne imagery and GIS analysis techniques; (iv) to explore predictive modelling techniques using geospatial data. In Paper (IV) human population occurrence and abundance in the Taita Hills highlands was predicted using the generalized additive modelling (GAM) technique. Paper (V) presents techniques to enhance fire prediction and burned area estimation at a regional scale in East Caprivi Namibia. Paper (VI) compares eight state-of-the-art predictive modelling methods to improve fire prediction, burned area estimation and fire risk mapping in East Caprivi Namibia. The results in Paper (I) showed that geospatial data can be managed effectively using advanced relational database management systems. Metapopulation data for Melitaea cinxia butterfly was successfully combined with GPS-delimited habitat patch information and climatic data. Using the geospatial database, spatial analyses were successfully conducted at habitat patch level or at more coarse analysis scales. Moreover, this study showed it appears evident that at a large-scale spatially correlated weather conditions are one of the primary causes of spatially correlated changes in Melitaea cinxia population sizes. In Paper (II) spatiotemporal characteristics of Socupulini moths description, diversity and distribution were analysed at a world-wide scale and for the first time GIS techniques were used for Scopulini moth geographical distribution analysis. This study revealed that Scopulini moths have a cosmopolitan distribution. The majority of the species have been described from the low latitudes, sub-Saharan Africa being the hot spot of species diversity. However, the taxonomical effort has been uneven among biogeographical regions. Paper III showed that forest cover change can be analysed in great detail using modern airborne imagery techniques and historical aerial photographs. However, when spatiotemporal forest cover change is studied care has to be taken in co-registration and image interpretation when historical black and white aerial photography is used. In Paper (IV) human population distribution and abundance could be modelled with fairly good results using geospatial predictors and non-Gaussian predictive modelling techniques. Moreover, land cover layer is not necessary needed as a predictor because first and second-order image texture measurements derived from satellite imagery had more power to explain the variation in dwelling unit occurrence and abundance. Paper V showed that generalized linear model (GLM) is a suitable technique for fire occurrence prediction and for burned area estimation. GLM based burned area estimations were found to be more superior than the existing MODIS burned area product (MCD45A1). However, spatial autocorrelation of fires has to be taken into account when using the GLM technique for fire occurrence prediction. Paper VI showed that novel statistical predictive modelling techniques can be used to improve fire prediction, burned area estimation and fire risk mapping at a regional scale. However, some noticeable variation between different predictive modelling techniques for fire occurrence prediction and burned area estimation existed.

Hila- ja kuviotason laskennan vaikutus kuvion kokonaistilavuuteen, tallennustilaan ja laskentaaikaan teoreettista läpimittajakaumaa ja runkolukusarjaa käyttämällä

Metsäsuunnittelussa tarvittavan metsävaratiedon keräämisessä ollaan Suomessa siirtymässä kuvioittaisesta arvioinnista laserkeilaus- ja ilmakuvapohjaiseen kaukokartoitukseen. Tämän tutkimuksen tarkoitus oli selvittää kuvion kokonaistilavuuden ja läpimittajakauman ennustamisen tarkkuus koealan metsikkö- ja puustotunnuksista MSN-, PRM-, ML- ja FMM-menetelmiä sekä Weibull-jakaumaa hyödyntäen seuraavilla tavoilla: 1. PRM-menetelmällä hilatasolla, 2. PRMmenetelmällä kuviotasolla, 3. ML-menetelmällä hilatasolla ja 4. ML-menetelmällä kuviotasolla. Lisäksi kuvion kokonaistilavuuden ennustamisen tarkkuus selvitettiin hyödyntäen kuviolle tuotettua runkolukusarjaa. Tulokset laskettiin puulajikohtaisesti männylle, kuuselle, koivulle ja muille puulajeille. Puulajien tulokset laskettiin kuviotasolla yhteen. Lisäksi selvitettiin menetelmien laskenta-ajan ja tallennustilan tarve. Tutkimuksen aineistona käytettiin Hämeen ammattikorkeakoulun Evon toimipisteen metsistä mitattuja kiinteäsäteisiä ympyräkoealoja, joita oli 249 kappaletta. Hakkuukoneella mitattiin 12kuvion, joiden pinta-alat vaihtelivat välillä 0,2 – 1,94 hehtaaria, puustotiedot. Aluepohjaisen laserkeilausaineiston pulssin tiheys oli 1,8/m2 ja ilmakuvien pikselikoko 0,5 metriä. Kuvion kokonaistilavuus ennustettiin tai estimoitiin laserkeilaus- ja ilmakuva-aineiston piirteiden avulla koealojen puustotunnuksista. Tulokset laskettiin erikseen kaikille kuvioille ja kuvioille, joiden pinta-ala oli yli 0,5 hehtaaria. Yli 0,5 hehtaarin kuvioita oli 8 kappaletta. Kuvion hilojen naapureina käytettiin 1 - 10 koealaa. Menetelmästä ja naapurien määrästä riippuen kokonaistilavuuden suhteellinen RMSE ja harha vaihtelivat välillä 20,76 – 52,86 prosenttia ja -12,04 – 46,54 prosenttia. Vastaavat luvut yli 0,5 hehtaarin kuvioilla olivat 6,74 – 59,41 prosenttia ja -8,04 – 49,59 prosenttia. Laskenta-aika vaihteli menetelmien ja käytettyjen naapurien määrän mukaan voimakkaasti. Kehittyneemmällä ohjelmoinnilla ja ohjelmistolla laskenta-ajat voivat laskea merkittävästi. Tallennustila ei testatuilla menetelmillä ole rajoittava tekijä laajassakaan mittakaavassa. Läpimittajakauman perusteella PRM-menetelmä ennustaa puulajille erittäin kapean läpimittajakauman, jos koeala koostuu vain muutamasta lähes samankokoisesta puusta. Tämä vaikutti tuloksiin erityisesti menetelmällä PRM2.

Valokuvallistettu luonto : I. K. Inhan tuotanto luonnon merkityksellistäjänä

Photographized nature I. K. Inha s work as a signification of nature The dissertation examines, through the work of the Finnish photographer and writer I. K. Inha (formerly Konrad Into Nyström) (1865 1930), the different ways in which the signification of nature is achieved. The principal material consists of Inha s work from 1890 to 1925, from which a number of photographs and texts are considered and upon which the photographization of nature is contemplated. The dissertation addresses the issue of how nature is conceived and how the act of photographizing it can be defined. The methodical context of the study is composed of three thematic baskets that structure the material and which consist of narrations on Finnish national perception, nature conservation and understanding the world. In the first case nature is seen as the natural environment encompassing lakes, seashores, forests, and hills, which at the time were often perceived from a utilitarian viewpoint. By the photographization they generated a pictorial narrative that could be shared. The natural environment was thus turned into landscape by means of photography, following the global pictorial concepts picturesque and sublime, as well as the national canons that had been developed in literature and the visual arts. In the narrations concerning nature conservation, the photographization did not merely occur within the limits of presuppositions, but rather nature was given the opportunity to unfold itself. While the photograph was being established as a basis for supporting nature conservation or to highlight the destruction of nature at the hand of Man, an attempt was made to represent subjects that were difficult to convey in photographs, such as nature s power or the miracle of growth. The thesis suggests, that in the third case the concept of nature broke away from its strict interconnection with the natural environment and led to a contemplation of nature that is perceivable in a person. In this context the photograph and the photographization are interpreted as an attempt to understand a person and his or her very existence in the world, while this same existential wonder is seen as being embodied in Inha s portrait of a rune singer and in his photographs of forest interior and water. Further, the thesis asks whether photographing nature could be interpreted as an action similar to the idea of the phenomenological reduction as a means of bypassing the photographer s prevailing way of being.

Kurkistus lapsen arkeen vuorohoidossa

Nonstandard hour child care is a subject rarely studied. From an adult's perspective it is commonly associated with a concern for child's wellbeing. The aim of this study was to view nonstandard hour child care and its everyday routines from children´s perspective. Three research questions were set. The first question dealt with structuring of physical environment and time in a kindergarten providing nonstandard hour child care. The second and third questions handled children s agency and social interaction with adults and peers. The research design was qualitative, and the study was carried out as a case study. Research material was mainly obtained through observation, but interviews, photography and written documents were used as well. The material was analysed by means of content analysis. The study suggests that the physical environment and schedule of a kindergarten providing nonstandard hour child care are similar to those of kindergartens in general. The kindergarten's daily routine enabled children s active agency especially during free play sessions for which there was plenty of time. During free play children were able to interact with both adults and peers. Children s individual day care schedules challenged interaction between children. These special features should be considered in developing and planning nonstandard hour child care. In other word, children's agency and opportunities to social interaction should be kept in mind in organising the environment of early childhood education in kindergartens providing nonstandard hour child care.

Monitoring Indigenous Tropical Montane Forests in the Taita Hills Using Airborne Digital Camera Imagery

The loss and degradation of forest cover is currently a globally recognised problem. The fragmentation of forests is further affecting the biodiversity and well-being of the ecosystems also in Kenya. This study focuses on two indigenous tropical montane forests in the Taita Hills in southeastern Kenya. The study is a part of the TAITA-project within the Department of Geography in the University of Helsinki. The study forests, Ngangao and Chawia, are studied by remote sensing and GIS methods. The main data includes black and white aerial photography from 1955 and true colour digital camera data from 2004. This data is used to produce aerial mosaics from the study areas. The land cover of these study areas is studied by visual interpretation, pixel-based supervised classification and object-oriented supervised classification. The change of the forest cover is studied with GIS methods using the visual interpretations from 1955 and 2004. Furthermore, the present state of the study forests is assessed with leaf area index and canopy closure parameters retrieved from hemispherical photographs as well as with additional, previously collected forest health monitoring data. The canopy parameters are also compared with textural parameters from digital aerial mosaics. This study concludes that the classification of forest areas by using true colour data is not an easy task although the digital aerial mosaics are proved to be very accurate. The best classifications are still achieved with visual interpretation methods as the accuracies of the pixel-based and object-oriented supervised classification methods are not satisfying. According to the change detection of the land cover in the study areas, the area of indigenous woodland in both forests has decreased in 1955 2004. However in Ngangao, the overall woodland area has grown mainly because of plantations of exotic species. In general, the land cover of both study areas is more fragmented in 2004 than in 1955. Although the forest area has decreased, forests seem to have a more optimistic future than before. This is due to the increasing appreciation of the forest areas.