Papers by Christoph Perger
Global land cover is an essential climate variable and a key biophysical driver for earth system ... more Global land cover is an essential climate variable and a key biophysical driver for earth system models. While remote sensing technology, particularly satellites, have played a key role in providing land cover datasets, large discrepancies have been noted among the available products. Global land use is typically more difficult to map and in many cases cannot be remotely sensed. In-situ or ground-based data and high resolution imagery are thus an important requirement for producing accurate land cover and land use datasets and this is precisely what is lacking. Here we describe the global land cover and land use reference data derived from the Geo-Wiki crowdsourcing platform via four campaigns. These global datasets provide information on human impact, land cover disagreement, wilderness and land cover and land use. Hence, they are relevant for the scientific community that requires reference data for global satellite-derived products, as well as those interested in monitoring global terrestrial ecosystems in general. data integration objective • observation design • database creation objective • citizen science design Measurement Type(s) land cover Technology Type(s) image analysis Factor Type(s) Sample Characteristic(s) Earth • planetary surface
International Journal of Spatial Data Infrastructures Research, ,, Feb 3, 2018
Citizen science is quickly becoming one of the most effective tools for the rapid and low-cost co... more Citizen science is quickly becoming one of the most effective tools for the rapid and low-cost collection of environmental information, filling a long recognized gap in in-situ data. Incentivizing citizens to participate, however, remains a challenge, with gaming being widely recognized as an effective solution to overcome the participation barrier. Building upon well-known gaming mechanics, games provide the user with a competitive and fun environment. This paper presents three different applications that employ game mechanics and have generated useful information for environmental science. Furthermore, it describes the lessons learnt from this process to guide future efforts.
Remote Sensing, Jul 22, 2017
Accuracy assessment, also referred to as validation, is a key process in the workflow of developi... more Accuracy assessment, also referred to as validation, is a key process in the workflow of developing a land cover map. To make this process open and transparent, we have developed a new online tool called LACO-Wiki, which encapsulates this process into a set of four simple steps including uploading a land cover map, creating a sample from the map, interpreting the sample with very high resolution satellite imagery and generating a report with accuracy measures. The aim of this paper is to present the main features of this new tool followed by an example of how it can be used for accuracy assessment of a land cover map. For the purpose of illustration, we have chosen GlobeLand30 for Kenya. Two different samples were interpreted by three individuals: one sample was provided by the GlobeLand30 team as part of their international efforts in validating GlobeLand30 with GEO (Group on Earth Observation) member states while a second sample was generated using LACO-Wiki. Using satellite imagery from Google Maps, Bing and Google Earth, the results show overall accuracies between 53% to 61%, which is lower than the global accuracy assessment of GlobeLand30 but may be reasonable given the complex landscapes found in Kenya. Statistical models were then fit to the data to determine what factors affect the agreement between the three interpreters such as the land cover class, the presence of very high resolution satellite imagery and the age of the image in relation to the baseline year for GlobeLand30 (2010). The results showed that all factors had a significant effect on the agreement.
Scientific Data, Jun 13, 2017
Global land cover is an essential climate variable and a key biophysical driver for earth system ... more Global land cover is an essential climate variable and a key biophysical driver for earth system models. While remote sensing technology, particularly satellites, have played a key role in providing land cover datasets, large discrepancies have been noted among the available products. Global land use is typically more difficult to map and in many cases cannot be remotely sensed. In-situ or ground-based data and high resolution imagery are thus an important requirement for producing accurate land cover and land use datasets and this is precisely what is lacking. Here we describe the global land cover and land use reference data derived from the Geo-Wiki crowdsourcing platform via four campaigns. These global datasets provide information on human impact, land cover disagreement, wilderness and land cover and land use. Hence, they are relevant for the scientific community that requires reference data for global satellite-derived products, as well as those interested in monitoring global terrestrial ecosystems in general. data integration objective • observation design • database creation objective • citizen science design Measurement Type(s) land cover Technology Type(s) image analysis Factor Type(s) Sample Characteristic(s) Earth • planetary surface
Представлена открытая интернет-платформа LACO-Wiki.net, целью которой является организация процес... more Представлена открытая интернет-платформа LACO-Wiki.net, целью которой является организация процесса валидации карт растительности и землепользования. Описан весь процесс валидации от загрузки исходной карты до получения отчѐта со стандартными оценками точности. Помимо решения частных задач, валидационные точки накапливаются для последующего использования в других проектах, в том числе для калибровки/валидации глобальных карт. LACO-Wiki может быть полезен в научных, образовательных и практических задачах. brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by International Institute for Applied Systems Analysis (IIASA)
Surveys in Geophysics, May 11, 2019
The land area covered by freely available very high-resolution (VHR) imagery has grown dramatical... more The land area covered by freely available very high-resolution (VHR) imagery has grown dramatically over recent years, which has considerable relevance for forest observation and monitoring. For example, it is possible to recognize and extract a number of features related to forest type, forest management, degradation and disturbance using VHR imagery. Moreover, time series of medium-to-high-resolution imagery such as MODIS, Landsat or Sentinel has allowed for monitoring of parameters related to forest cover change. Although automatic classification is used regularly to monitor forests using medium-resolution imagery, VHR imagery and changes in web-based technology have opened up new possibilities for the role of visual interpretation in forest observation. Visual interpretation of VHR is typically employed to provide training and/or validation data for other remote sensing-based techniques or to derive statistics directly on forest cover/forest cover change over large regions. Hence, this paper reviews the state of the art in tools designed for visual interpretation of VHR, including Geo-Wiki, LACO-Wiki and Collect Earth as well as issues related to interpretation of VHR imagery and approaches to quality assurance. We have also listed a number of success stories where visual interpretation plays a crucial role, including a global forest mask harmonized with FAO FRA country statistics; estimation of dryland forest area; quantification of deforestation; national reporting to the UNFCCC; and drivers of forest change.
The validation of land cover products is an important step in the workflow of generating a land c... more The validation of land cover products is an important step in the workflow of generating a land cover map from remotely-sensed imagery. Many students of remote sensing will be given exercises on classifying a land cover map followed by the validation process. Many algorithms exist for classification, embedded within proprietary image processing software or increasingly as open source tools. However, there is little standardization for land cover validation, nor a set of open tools available for implementing this process. The LACO-Wiki tool was developed as a way of filling this gap, bringing together standardized land cover validation methods and workflows into a single portal. This includes the storage and management of land cover maps and validation data; step-by-step instructions to guide users through the validation process; sound sampling designs; an easy-to-use environment for validation sample interpretation; and the generation of accuracy reports based on the validation proc...
The involvement of citizens in scientific activities from data collection to hypothesis generatio... more The involvement of citizens in scientific activities from data collection to hypothesis generation is referred to as citizen science. The majority of citizen involvement tends to be on the data collection side, where numerous crowdsourcing platforms have been built to involve citizens in image interpretation, online mapping and other micro-tasks that would not otherwise have been possible. There has been increasing attention directed towards how citizen-contributed data can be used for improved calibration and validation of satellite-derived products, such as land cover, as well as data for modeling purposes. This poster will provide examples of tools and applications in the area of citizen science and crowdsourcing within the Earth Observation Systems group of the IIASA Ecosystem Services Program. These tools include Geo-Wiki, mobile gaming apps such as Cropland Capture and Picture Pile, and other high-frequency mobile data collection tools. Some of the crowdsourced data have led t...
Protecting the ocean is essential for the sustainability of the planet. Oceans provide food and l... more Protecting the ocean is essential for the sustainability of the planet. Oceans provide food and livelihood for human populations, host vast biodiversity and ecosystems and provide climate regulatory services. However, due to the vastness of the oceans, monitoring ocean pollution and health is logistically challenging and expensive. This is particularly true for plastics. In the last 50 years, global production of plastics has increased more than 22-fold, and only an estimated 9% of plastics produced have been recycled1; Moreover, there is a lack of information on the volume of plastic that is currently in the ocean, where that plastic accumulates, and the process of how plastic breaks down into microplastic as well as a lack of information on how plastic affects ecosystem or human health. Answering these questions requires new ways of collecting and analyzing data. Citizen science and complementary activities, like targeted beach clean-ups, not only provide a cost effective mechanis...
Global Field Sizes provide the research community with valuable information to tackle the challen... more Global Field Sizes provide the research community with valuable information to tackle the challenge of food security, in particular, of smallholder farmers, who often make up the most vulnerable parts of a population, living in poverty. To fill the gaps of missing information, especially for countries that have a limited food supply and lack a well-developed agricultural monitoring system, in June 2017, the IIASA Geo-Wiki team () ran the Global Field Size campaign, encouraging citizen scientists to classify field sizes on satellite images. The campaign was aimed at developing a global field sizes dataset to create an improved global cropland field sizes map for agricultural monitoring and food security assessments. During the campaign, the crowd was asked to identify whether there were fields in a certain location, and determine the relevant field sizes via visual interpretation of very high-resolution Google and Bing imagery. A "field" was defined as an agricultural area that included annual or perennial croplands, fallow, shifting cultivation, pastures or hayfields. Within one month, 130 participants completed 390,000 tasks -that is, they classified the field sizes in 130,000 locations around the globe. This study presents a new freely available global field sizes dataset as the result of the campaign and a global map of dominant field sizes. These data could be used as input for agricultural management in ecosystem models. The field sizes dataset can also help to determine what types of satellite data are needed for agricultural monitoring in different parts of the world, with areas dominated by small field sizes requiring satellite imagery of increased precision.
Scientific Data, 2019
Forest biomass is an essential indicator for monitoring the Earth’s ecosystems and climate. It is... more Forest biomass is an essential indicator for monitoring the Earth’s ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world’s forests. All plot estimates are geolocated and have a size that allows for direct comparison with many ...
Surveys in Geophysics, 2019
The land area covered by freely available very high-resolution (VHR) imagery has grown dramatical... more The land area covered by freely available very high-resolution (VHR) imagery has grown dramatically over recent years, which has considerable relevance for forest observation and monitoring. For example, it is possible to recognize and extract a number of features related to forest type, forest management, degradation and disturbance using VHR imagery. Moreover, time series of medium-to-high-resolution imagery such as MODIS, Landsat or Sentinel has allowed for monitoring of parameters related to forest cover change. Although automatic classification is used regularly to monitor forests using medium-resolution imagery, VHR imagery and changes in web-based technology have opened up new possibilities for the role of visual interpretation in forest observation. Visual interpretation of VHR is typically employed to provide training and/or validation data for other remote sensing-based techniques or to derive statistics directly on forest cover/forest cover change over large regions. Hence, this paper reviews the state of the art in tools designed for visual interpretation of VHR, including Geo-Wiki, LACO-Wiki and Collect Earth as well as issues related to interpretation of VHR imagery and approaches to quality assurance. We have also listed a number of success stories where visual interpretation plays a crucial role, including a global forest mask harmonized with FAO FRA country statistics; estimation of dryland forest area; quantification of deforestation; national reporting to the UNFCCC; and drivers of forest change.
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Papers by Christoph Perger