Optimizing Land Cover Classification Accuracy for Change Detection: A Combined Pixel-based and Object-based Approach in a Mountainous Area in Mexico

Applied Geography

Applied Geography, Volume 34, May 2012

Jesus Aguirre-Gutiérrez, Arie C. Seijmonsbergen, and Joost F. Duivenvoorden


  • The land cover classification accuracy is optimized with a combined approach.
  • The optimized classification is the input in a change detection analysis.
  • This method produces higher classification and change detection accuracies.
  • This approach can potentially be applied to other mountainous regions.

“Inventories of past and present land cover changes form the basis of future conservation and landscape management strategies. Modern classification techniques can be applied to more efficiently extract information from traditional remote-sensing sources. Landsat ETM+ images of a mountainous area in Mexico form the input for a combined object-based and pixel-based land cover classification. The land cover categories with the highest individual classification accuracies determined based on these two methods are extracted and merged into combined land cover classifications. In total, seven common land cover categories were recognized and merged into single combined best-classification layers. A comparison of the overall classification accuracies for 1999 and 2006 of the pixel-based (0.74 and 0.81), object-based (0.77 and 0.71) and combined (0.88 and 0.87) classifications shows that the combination method produces the best results. These combined classifications then form the input for a change detection analysis between the two dates by applying post-classification, object-based change analysis using image differencing. It is concluded that the combined classification method together with the object-based change detection analysis leads to an improved classification accuracy and land cover change detection. This approach has the potential to be applied to land cover change analyses in similar mountainous areas using medium-resolution imagery.”

Sensor Web Services for Early Flood Warnings Based on Soil Moisture Profiles

XXII ISPRS Congress, 25 August to 01 September 2012, Melbourne, Australia

Thomas Brinkhoff and Stephan Jansen

“Recent disastrous floodings have demonstrated the demand for early flood warnings. This need will be enforced by the expected climate change that probably leads to more torrential rain. In general, flood forecasts concentrate on large rivers considering water gauges. However, there exist a large number of smaller drainage areas with a size of 100 to 1000 square kilometers. In such areas, disastrous drainages may happen after heavy rain that cannot reasonably be observed by gauges because the water level changes very fast without having enough time for warnings.

WEBBOS web client depicting the sensors of a sensor network

WEBBOS web client depicting the sensors of a sensor network.

“Thus, the creation of early flood warnings for small drainage areas is still an unsolved challenge. One promising approach for solving this problem is the observation of the soil humidity because that measure decides how much of the precipitation will drain off. WEBBOS is a joint project of two universities funded by the German Federal Ministry of Education and Research. It has the objective to build a web-based sensor system for early flood warnings by measuring soil moisture profiles. Within this project, special sensors measuring the soil humidity in different depths have been developed and successfully tested. These sensors were integrated into sensor nodes that form local sensor networks. Such a sensor network should be located in an area with a high variety of soil humidity, which typically happens near to small rivers on sloping terrains.

“Like in other early-warning and disaster management systems, it is important to incorporate the sensor measurements into a geospatial information service that allows managing sensor data. This encloses the visualization of the sensor measurements and the control of the soil humidity sensors as well as the detection and processing of alarm events. Interoperability is an important issue for such systems. Therefore, the Open Geospatial Consortium (OGC) started the Sensor Web Enablement (SWE) initiative 5 years ago and specified several services and data models in the meantime. The 52° North Sensor Web framework is the most prominent implementation of SWE specifications.

“WEBBOS implemented its information system using those specifications and the 52° North SWE framework. Many standard requirements can be solved by following such an approach without additional efforts. However, often there are important demands that need more sophisticated solutions. Such cases and their solutions for the WEBBOS project will be discussed in the following:

“The support of early flood warnings based on soil moisture profiles requires temporal 3D measurements and 3D models of soil humidity for each sensor network: Only the relation and difference between the humidity in different depths and their development over the time allow detecting relevant events. The temporal aspect is sufficiently covered by the current SWE specifications. However, these specifications and their implementation are mainly 2D-oriented. The latter is also caused by the underlying spatial database systems which are restricted to simple feature geometries. For solving this challenge, a layered sensor model has been developed and applied to the SWE implementation. This enables us to cope with these restrictions.

“An important issue for such systems is the detection of potentially dangerous situations. This requires the description of spatio-temporal events and their detection. For this purpose, the OCG currently proposed (as discussion papers) the Sensor Event Service (SES) and the Event Pattern Markup Language (EML). The WEBBOS project demonstrated that these specifications can be successfully applied for the evaluation of soil moisture profile measurements.

“Standard visualization tools are often not sufficient for an adequate visualization of sensor data. However, the use of SWE services restricts and formalizes the syntax and semantics of the sensor measurements and of sensor metadata. Therefore, open toolkits are well-suited for developing flexible solutions that can be easily adapted to the requirements of special applications. In case of the WEBBOS project, we followed this approach by extending the popular JavaScript map library “OpenLayers”. We introduced subclasses for sensors and sensor data that can be flexibly used in standard vector layers of OpenLayers. The web client allows retrieving sensor data and metadata by the Sensor Observation Service (SOS) as well as controlling and evaluating the SES.

“Overall, the WEBBOS project demonstrated the strengths and deficiencies of the current SWE services and provided feasible solutions for sensor networks measuring soil moisture on the top of standard geospatial software packages. ”


Crowdsourcing, Citizen Sensing and Sensor Web Technologies for Public and Environmental Health Surveillance and Crisis Management: Trends, OGC Standards and Application Examples

International Journal of Health GeographicsInternational Journal of Health Geographics 10:67, Published 21 December 2011

Maged N Kamel Boulos, Bernd Resch, David N Crowley, John G Breslin, Gunho Sohn, Russ Burtner, William A Pike, Eduardo Jezierski and Kuo-Yu Slayer Chuang

“‘Wikification of GIS by the masses’ is a phrase-term first coined by Kamel Boulos in 2005, two years earlier than Goodchild’s term ‘Volunteered Geographic Information’. Six years later (2005-2011), OpenStreetMap and Google Earth (GE) are now full-fledged, crowdsourced ‘Wikipedias of the Earth’ par excellence, with millions of users contributing their own layers to GE, attaching photos, videos, notes and even 3-D (three dimensional) models to locations in GE.

Mobile CO measurements in the city of Copenhagen (December 2009)

Mobile CO measurements in the city of Copenhagen (December 2009)

“From using Twitter in participatory sensing and bicycle-mounted sensors in pervasive environmental sensing, to creating a 100,000-sensor geo-mashup using Semantic Web technology, to the 3-D visualisation of indoor and outdoor surveillance data in real-time and the development of next-generation, collaborative natural user interfaces that will power the spatially-enabled public health and emergency situation rooms of the future, where sensor data and citizen reports can be triaged and acted upon in real-time by distributed teams of professionals, this paper offers a comprehensive state-of-the-art review of the overlapping domains of the Sensor Web, citizen sensing and ‘human-in-the-loop sensing’ in the era of the Mobile and Social Web, and the roles these domains can play in environmental and public health surveillance and crisis/disaster informatics. We provide an in-depth review of the key issues and trends in these areas, the challenges faced when reasoning and making decisions with real-time crowdsourced data (such as issues of information overload, “noise”, misinformation, bias and trust), the core technologies and Open Geospatial Consortium (OGC) standards involved (Sensor Web Enablement and Open GeoSMS), as well as a few outstanding project implementation examples from around the world. ”

A Land-use and Land-cover Modeling Strategy to Support a National Assessment of Carbon Stocks and Fluxes

Applied Geography

Applied Geography, Volume 34, May 2012

Terry L. Sohl, Benjamin M. Sleeter, Zhiliang Zhu, Kristi L. Sayler, Stacie Bennett, Michelle Bouchard, Ryan Reker, Todd Hawbaker, Anne Wein, Shuguang Liu, Ronald Kanengieter, William Acevedo


  • The USGS is analyzing scenarios of land-cover change and resultant effects on carbon.
  • A unique land-cover modeling framework was developed to support this work.
  • Downscaled scenarios consistent with IPCC scenarios were developed.
  • The FORE-SCE model was used to create spatially explicit land-cover projections.
  • The methodology is demonstrated for the first completed U.S. ecoregion.

“Changes in land use, land cover, disturbance regimes, and land management have considerable influence on carbon and greenhouse gas (GHG) fluxes within ecosystems. Through targeted land-use and land-management activities, ecosystems can be managed to enhance carbon sequestration and mitigate fluxes of other GHGs. National-scale, comprehensive analyses of carbon sequestration potential by ecosystem are needed, with a consistent, nationally applicable land-use and land-cover (LULC) modeling framework a key component of such analyses. The U.S. Geological Survey has initiated a project to analyze current and projected future GHG fluxes by ecosystem and quantify potential mitigation strategies. We have developed a unique LULC modeling framework to support this work. Downscaled scenarios consistent with IPCC Special Report on Emissions Scenarios (SRES) were constructed for U.S. ecoregions, and the FORE-SCE model was used to spatially map the scenarios. Results for a prototype demonstrate our ability to model LULC change and inform a biogeochemical modeling framework for analysis of subsequent GHG fluxes. The methodology was then successfully used to model LULC change for four IPCC SRES scenarios for an ecoregion in the Great Plains. The scenario-based LULC projections are now being used to analyze potential GHG impacts of LULC change across the U.S.”

Spatial Patterns of Biological Diversity in a Neotropical Lowland Savanna of Northeastern Bolivia

Biodiversity and Conservation, Online 22 February 2011

Daniel M. Larrea-Alcázar, Dirk Embert, Luis F. Aguirre, Boris Ríos-Uzeda, and Marlene Quintanilla, et al.

“Understanding large-scale patterns of beta- and alpha diversity is essential for ecoregional conservation planning. Using the 110,000 km2 shallow basin of the Beni savannas of northeastern Bolivia, we examined the spatial patterns of biological diversity of four taxonomic groups (bats, palms, reptiles, and amphibians). Since the Beni savannas are shaped by cycles of drought and flood, and farming, which, together with topography, create a mosaic of sub-ecoregions from Amazonian forests to aquatic vegetation, we hypothesize that this landscape heterogeneity results in a high turnover in species composition across sub-ecoregions. We compiled species lists for each taxon and modeled the potential distribution of each species using the algorithm MaxEnt. For those species whose modeled potential distribution produced incongruous results, we built presence-absence maps. Using the potential distribution maps, we estimated the lists of species for each sub-ecoregion. In order to establish present similarities in species composition between sub-ecoregions, we constructed dendrograms using cluster analysis of presence-absence matrices. The sub-ecoregions associated with the Moxos (southern part of the Beni savannas) were richer than the sub-ecoregions composing the Beni Cerrado (northern part of the Beni savannas). Centers of species richness were detected in the savanna-type sub-ecoregions (bats and reptiles) or associated with the Várzea forests (palms and amphibians). A south-north gradient in the pattern of distribution of four taxonomic groups was also recorded. The results suggest that the patterns of biological diversity partially respond to the mosaic arrangement of the landscape. Future exercises on conservation planning will point to total target areas about 5,000 km². This area seems to be sufficient to contain the biological richness of the region at least for the taxa analyzed.”

Empirical Mapping of Suitability to Dengue Fever in Mexico using Species Distribution Modeling

Applied Geography

Applied Geography, Volume 33, April 2012

Elia Axinia Machado-Machado


  • Mapping dengue fever suitability empirically using species distribution modeling and cases.
  • Providing continuous maps of suitability to dengue fever for each municipality in Mexico.
  • Integrating the interactions between social and climatic factors associated with dengue fever.

“Dengue is considered the most important vector borne virus disease worldwide placing some 2.5 billion people at risk globally. Despite the public health concern about dengue fever, spatially explicit suitability assessments for this disease are limited due to data restrictions and the challenges posed by the complexity of the interactions among its risk factors, which involve social, economic, and ecological processes.

“This paper demonstrates an empirical approach to identify suitable areas for dengue fever using species distribution modeling and evaluates the relative contribution of climatic and socio-economic factors as dengue fever suitability determinants. Several models showing the potential distribution of dengue fever within all the Mexican municipalities are produced using different sets of predictor variables. The results suggest that at the scale of this study the climatic variables were more important determinants of suitability for dengue fever than the socio-economic variables considered in this study. All the models perform well (average testing AUC about 0.8) and show similar patterns. The model with the least number of variables and best performance includes the variables minimum temperature of the coldest month, mean temperature of the wettest quarter, and annual precipitation. However, there is not a high variability of AUC scores among the models generated.”

Use of Spatial Analysis to Evaluate the Quality of Pharmaceutical Services

CIFARP8th International Congress of Pharmaceutical Sciences (CIFARP 2011), Ribeirão Preto, Brazil, 21-24 August 2011


“The pharmaceutical service quality contributes to the rational use of medicines, ensuring the patient a drug therapy used appropriately, safely and effectively when they are accessible to all. Moreover, in countries of the European union the geographic and demographic criteria are considered for evaluating pharmaceutical services. This way, it becomes necessary to investigate the geographical distribution of community pharmacies for an equal access, once there is no law in São Mateus regulating the opening  of new outlets. Thus, this study aims to know the spatial distribution of the community pharmacies in São Mateus city, Espírito Santo state, Brazil and its coverage area. This is the first phase of the project to evaluate the quality of pharmaceutical services in the study area.

Spatial distribution of community pharmacies. São Mateus-ES (A) zoning area (500m buffer) (B) detail of the intersection between coverage areas of two pharmacies (C).

Spatial distribution of community pharmacies. São Mateus-ES (A) zoning area (500m buffer) (B) detail of the intersection between coverage areas of two pharmacies (C).

Evaluation of Maize Variety Suitability on Lodging in Target Environments based on GIS

Annals of GISAnnals of GIS, Volume 17, Issue 4, 2011

Chunqiao Mi, Xiaodong Zhang, Shaoming Li, Jianyu Yang & Dehai Zhu

“Lodging is one of the major problems in maize production which causes severe yield loss every year all over the world. In the present study, the lodging suitability of different maize varieties in target growing environments was investigated based on geographical information science. A total of 401 maize planting counties in northeast China and northern China were selected as study areas. The mean and standard deviation of environment accumulated temperature in vegetative stage of maize were calculated from raw temperature data obtained from 167 meteorology stations in these areas. The variety lodging resistance was determined based on the data of national regional variety trials for maize, and the environment lodging stress was measured using field survey data on lodging. Probability analysis based on the calculated values of environment accumulated temperature in vegetative stage of maize was utilized to determine whether a maize variety can be physically mature in a planting county, and lodging suitability of the variety was evaluated with geographical information science combining variety lodging resistance and local environment lodging stress together. A new maize variety NH1101 was taken as an example to illustrate the modeling and calculating procedures. The result shows that, from southwest to northeast of the study areas, the overall suitability trend changes from nonsuitable to suitable, then to not very suitable. And it is demonstrated that the lodging suitability is not only related to the variety resistance but also to the local environment stress.”

The Spatial Variability of Heat-related Mortality in Massachusetts

Applied Geography

Applied Geography, Volume 33, April 2012

David Hattis, Yelena Ogneva-Himmelberger, and Samuel Ratick


  • We assess the spatial distribution of heat-related mortality in Massachusetts.
  • Areas with high elderly and African–American populations have elevated mortality on hot days.
  • Urban areas do not exhibit significantly higher heat-related mortality than rural areas.

” This study assesses heat-related mortality in Massachusetts during the months of May through September from 1990 to 2008. Daily maximum apparent temperature was interpolated across space via kriging, and aggregated to 29 municipality groups (MGs), a spatial unit composed of municipalities that was designed to have minimal variation in population. Death certificate data were analyzed to determine the spatial distribution of excess mortality on days that exceeded the 85th, 90th, and 95th percentiles of apparent temperature. We find that the average statewide mortality anomalies were 5.11, 6.26, and 7.26 deaths on days exceeding the 85th, 90th, and 95th percentiles of apparent temperature respectively. A linear stepwise regression showed that percent African–American population and percent elderly population (those above the age of 65) were positively associated with an MG’s mortality anomaly on days exceeding the 85th percentile of apparent temperature (p < 0.05). In spite of the urban heat island effect, our measure of urbanization was not associated with higher rates of heat-related mortality.”

Recent Progress in the ANUDEM Elevevation Gridding Procedure

Geomorphometry 2011Geomorphometry 2011, 07-09 September 2011, Esri, Redlands, California

Michael Hutchinson

“Topography plays a fundamental role in modulating land surface and atmospheric processes across a wide range of spatial scales (Hutchinson 2008). Thus digital elevation models (DEMs) have played a key role in supporting mesoscale representations of surface climate as well as in supporting finer scale representations of surface hydrology and catchment processes. The ANUDEM locally adaptive elevation gridding procedure (Hutchinson 1989, 2007) is commonly used to calculate these elevation models in regular grid form. Key features of the method include its computational efficiency, allowing it to be applied to very large data sets, and a range of locally adaptive features, including a drainage enforcement algorithm that attempts to maintain connected drainage structure in the interpolated DEM, and algorithms to incorporate data streamlines, lakes and cliffs. This paper describes current progress in the ANUDEM procedure to better represent lakes and to effectively process noisy, high resolution elevation data. Such data are becoming increasingly common. The underlying multi-grid interpolation procedure remains effective in effectively representing lakes and cliffs and in stably interpolating high resolution elevation data. Correlated errors in source elevation data can also be specifically accommodated. The multi-grid procedure also plays a crucial role in enabling the application of drainage enforcement and in initializing heights on data streamlines. This can prevent corruption of stream heights by noisy elevation values and improve the overall representation of drainage structure in the presence of dense noisy elevation source data.”

All presentation materials and reviewed papers from Geomorphometry 2011 are available at http://geomorphometry.org/content/geomorphometry-2011-programme.