Frequently Asked Questions - FAQ

Fields of application of the Monitor of Settlement and Open Space Development as well as relevance to other information portals

Which topics are presented in the IOER Monitor?

The IOER Monitor only uses official basic geodata (ATKIS Basis-DLM for land use, ALKIS for the analysis of building stocks), specialist geodata (legally designated flood zones, landscape preservation and nature conservation sites) as well as statistical data (population figures, GDP). No original source data is gathered.

How is the IOER Monitor integrated into Germany’s system of spatial monitoring?

A hierarchical classificatory system of land use is used, designed around the classes of usage in the official ATKIS and ALKIS basic geodata. The basic types of use, namely, settlement, transportation and open space, are each subdivided into two to three sub-types, leading to a total of 34 specific forms of land use. The ratio of land use to total area as well as the development over time are presented for the most important of these.

How do the indicator values on land usage within the IOER Monitor differ from those provided by public authorities?

The IOER Monitor uses official geo-topographical data (ATKIS Basis-DLM) rather than official land-use statistics, which are derived from property cadastres (ALKIS). In contrast to such cadastral data, geo-topographical data is regularly updated for the whole country. However, the smallest observed spatial unit is somewhat larger. This drawback will be resolved by as the harmonization of ALKIS and ATKIS.

Which actors can use the indicator values for which tasks?

Likely applications of indicator values, which are supplied at small-scale and over long time series for the whole country, are in devising policies of land saving, in environmental monitoring as well as spatial planning. For example:

  • Tasks of the federal and state governments (changes in primary indicators such as settlement and transportation infrastructure, land consumption, settlement density, loss of open space per resident, ecosystem services)
  • Environmental agencies of the individual Länder (e.g. comparison with other Länder)
  • Urban planning and environmental management (inner-city analysis within a raster map or at the level of urban districts). E.g. the accessibility of green areas.
  • Regional planning (support for communication and moderation)
  • Planning associations and municipal authorities (counties and municipalities)
  • Public surveying agencies or providers of basic geodata (information on data problems regarding implausible indicator values or changes in values)
  • NGOs - Media (basic information on the current state of land usage and development)
  • Research and teaching in the spatial sciences as well as the social sciences

Source data, nomenclature, methods of calculation, time periods and reliability

Which data sources are used to derive indicators?

The IOER Monitor only uses official basic geodata (ATKIS Basis-DLM for land use, ALKIS for the analysis of building stocks), specialist geodata (legally designated flood zones, landscape preservation and nature conservation sites) as well as statistical data (population figures, GDP). No original source data is gathered. 

Which forms of land usage are distinguished?

A hierarchical classificatory system of land use is used, designed around the classes of usage in the official ATKIS and ALKIS basic geodata. The basic types of use, namely, settlement, transportation and open space, are each subdivided into two to three sub-types, leading to a total of 34 specific forms of land use. The ratio of land use to total area as well as the development over time are presented for the most important of these. 

How reliable are the indicator values for spatial comparison?

The land use data of ATKIS Basis-DLM is gathered under a model designed by the Working Committee of the Surveying Authorities of the States (Arbeitsgemeinschaft der Vermessungsverwaltungen, AdV) on behalf of the Länder. There are some small differences between the individual Länder due to varying interpretations of the data gathering guidelines. It should be noted that for increasingly high data resolution, i.e. smaller spatial units or cell widths, the uncertainty in indicator values rises due to geometrical imprecision or disparities in the age of data. Hence, indicator values at municipal level tend to be less reliable than at the level of the Länder.

How reliable are indicator values for temporal comparison?

Temporal comparison is assured for indicator values by considering the indicated period of data capture, i.e. the values of the selected spatial unit for a particular time period correspond to the data supplied at the end of the respective year (also see next question). It should be noted that there exist differences in the gathering and updating of ATKIS data between the various Länder. The temporal comparison of data was undermined for some time as a result of the migration of ATKIS Basis-DLM (from 2008 – 2013 depending on the Land). Such effects are explicitly indicated in the tabular presentation.

How are indicator values checked?

Following the calculation process, indicator values are subject to a spatial comparison. The values are classified by administrative level and checked by means of aerial images for minimum and maximum values. Frequently, outlying values are due to errors in data capture; these are marked as such in the table tool. Subsequently, a comparison is undertaken between new indicator values and previous values of the time series. Clear disparities are checked by means of aerial imagery; these disparities are marked as data errors if they appear implausible and indicate an error in data capture.

How topical is the geodata used to derive the indicator values?

The ATKIS geodata used to derive the indicator values for a new time period is always captured at year-end (status as of 31.12.). This geodata is made available at the beginning of the following year as soon as the BKG has homogenised all data from the individual Länder. Then the indicator values are calculated for the IOER Monitor, reviewed in part by IOER Monitor team, and normally made publically available from March. Some indicators derived from other data sources are treated differently.

How topical is the geodata of each time period?

Every indicator map derived from ATKIS data is accompanied by an additional map indicating the mean topicality of the underlying data.

How are the administrative boundaries determined when calculating indicator values?

The indicator values are calculated for the latest valid administrative boundaries for which population data is available. Earlier timeframes are being converted accordingly. The official geometry of the administrative unit at scale 1:25,000 (VG25) is adopted for each administrative level. 

What do I have to observe when comparing indicator values over time?

Indicators on land usage are derived from topographical base geodata at the highest possible resolution. The nationwide updating of this data (changes in land use are determined by a comparison of aerial imagery) is a complex, time-consuming process and is carried out by the surveying agencies of the Länder in cycles of three to five years. The true age of data (basic topicality) therefore differs from the selected time period. This is indicated on an additional map as well as in the table of indicator values if relevant for the selected indicator. 

Why are indicator values missing for some spatial units?

Missing input data. Data needed to calculate the indicator is missing for the area in question.

Value cannot be calculated. Although data is available, the indicator value cannot be determined. This occurs in the case of relative parameters/indicators if the object type in the reference area is not present in the spatial unit (division by zero).

Wrong/implausible value. Despite a correct calculation, the indicator value is implausible. This particularly occurs in the case of incorrect base geodata (e.g. incorrect geometry or object types/attributes).

Why is it that gemeindefreie Gebiete (i.e. areas which do not belong to any municipality) in some cases show very high or implausible indicator values regarding settlements?

Due to the smallest inaccuracies in the geometries of the input data (ATKIS), settlement areas can be determined to protrude beyond actual administrative boundaries, i.e. into areas where no settlement actually exists. In the case of gemeindefreie Gebiete, generally no larger settlement areas exist to mask this error, so that such small erroneous settlement areas become highly significant. Such errors are preserved due to the fact that the official data is basically unaltered during the derivation of indicator values. In the tabular overview such gemeindefreie Gebiete are therefore hidden from view (they are shown in the map overview). However, they can be revealed by clicking on the menu selection.

Why do indicator values differ from official land survey data?

The disparities can be attributed to the use of different sources of input data. The indicator values of the Monitor of Settlement and Open Space Development are based on the ATKIS Basis-DLM, while the values of official land-use surveys according to the type of actual use are based on public cadastres (ALKIS). 

Which additional information is provided alongside the indicator values?

The derived indicator values are checked for plausibility. In certain cases additional notifications are given to assist in interpreting the values. No guarantee is given that such information is available in all cases. Notifications are:

Restricted comparison with previous values (change in attributes). Conversion of land form or corrections to the Basis-DLM data may undermine a comparison of indicator values between different time periods. In this case, large disparities in values do not reflect an actual trend but are mainly due to data corrections.

Calculated values based on a very small area. Small splintered areas arising from the unintended overlapping of objects in settlements over municipal boundaries can lead to very high indicator values, giving a distorted image of the real situation (cf. the question of implausible values in so-called gemeindefreie Gebiete).

The calculated indicator value incorporates large recreational areas (wildlife park, golf course, etc.) Wildlife parks and golf courses are areas of open space within settlements which are classified as settlement. Municipalities with such facilities may in some cases display a very high ratio of settlement area, even if these are actually areas of forest or meadow.

The calculated indicator value incorporates large open-cast mines. Open-cast mines are generally classified as open space. However, in certain constellations of spatial overlapping of the object types mining facility and industrial and commercial area, it can happen that these areas become classified (for technical reasons) as settlement area.

The calculated indicator value incorporates a military site. When interpreting indicator values for this spatial unit, it should be remembered that the values can be influenced by the presence of large military training areas.

Other notifications. In certain special cases other notifications are provided on published values. Such notifications are listed separately in the tabular view.

Questions regarding presentation and functionality

For which spatial configurations are indicators values given?

Indicators are generally calculated for all administrative units from the national, state (Land), district (divided into independent cities and counties), municipal associations to the municipal level for the entire national territory of the Federal Republic of Germany (excluding maritime areas) as well as for spatial and regional planning areas. In addition, selected indicators may be provided for cities with more than 50,000 residents as well as their administrative subdivisions (Stadtbezirke, Ortsteile or similar units). Values are not provided for municipalities if these are deemed to be unreliable. Indicator values are given in INSPIRE-compliant raster maps of cells width 100 m, 200 m, 500 m, 1,000 m, 5,000 m and 10,000 m. This enables an inter-municipal evaluation of the settlement and landscape structure. 

Do changes in administrative boundaries prevent temporal comparison?

No, indicator values of all time slices are calculated corresponding to the latest administrative boundaries. In this way the development of indicators can be followed back in time. In most cases it is possible to make a (more or less exact) forwards and backwards comparison over time.

The raster maps are independent of changes in administrative boundaries so that a forwards and backwards comparison is given in all cases.

Where can I find detailed background information on the indicators?

The method of calculation, the input data, the significance and interpretation of every indicator are provided in an indicator data sheet, which also specifies relevant references and publications. The meaning of each indicator value is often better understood by revealing the local geo-topography (WebAtlasDE, TopPlus). The visibility of such background maps can be changed using a slider. 

Can several areas be viewed at the same time?

Yes. Several areas can be selected at once within the map viewer (".Menüpunkt..") by searching for their names in the field "...XX". You can add and remove them by clicking on the names.


Several territorial units of one spatial level can be aggregated to form larger regions as described above (e. g. districts to metropolitan regions). After selecting any indicator, a corresponding map can be saved permanently under a number on the IOER server (Export: Create map link). When the map with this number is called up later (Load map link), the selected territorial units of the desired region appear. On this basis, other indicators for other times can also be displayed permanently.

How are values automatically classified?

Generally, classification is based on the values of the displayed areas, with the aim of achieving an even spread of classes (quantiles). In most cases this method of classification ensures a highly differentiated and well-contrasted presentation of values. Alternatively, values can be displayed in classes of equal width (Equal Intervals). 

Can several time periods be shown on the same map?

Yes, but only for raster maps. Under the “compare” mode you can compare two time periods by means of an interactive viewer. There also the grid size and indicators can be chosen freely.  

Can the map be supplemented with topographical information?

Yes. Under the background maps (top right corner), you can superimpose the borders of the Land and/or the city/county as well as rivers, railway network and the Autobahn/road network.

Is there an explanation of terms?

Click on the button in the top navigation bar (under "methodology") to go to a glossary of terms, which provides an explanation of the most important terms used by the IOER Monitor.

Questions regarding the data transfer of results from the IOER Monitor

Is it permissible to publish results from the IOER Monitor?

Yes. Every map, table or figure from the IOER Monitor may be published. However, data must be marked with the copyright notice “IOER Monitor©Leibniz Institute of Ecological Urban and Regional Development”.

How can I permanently save maps or send a link to a map in the IOER Monitor?

Every map as well additional settings selected by a user of the IOER Monitor system (classification, colour coding additional map elements, etc.) can be permanently saved as a map link, which can then be used to retrieve the map. Simply click on “generate map link” in order to save the current settings under a unique code. This code can be used to retrieve at any time.

Is it possible to integrate data from the IOER Monitor into my own GIS projects?

Yes. Most indicators are also provided as geo services, enabling the presentation of indicator maps (WMS) as well as data queries via WCS and WFS in other GI systems. 

For further use of the data please regard our terms of use.

How can I export data from the IOER Monitor?

Data can be exported directly from the IOER Monitor by clicking on geo services where available under the button “map integration/saving”. In addition, the map visualizations and data references can also be obtained via

Questions regarding further developments

Which new content is planned for the Monitor?

The database of the Monitor of Settlement and Open Space Development is regularly supplemented with new data for current time periods (geodata from the previous year is introduced at the beginning of March alongside the step-by-step compiling of data for earlier time periods) as well as new indicators. We are currently working on additional indicators to describe the level of soil sealing, on infill development and as well as the availability of development plots in built-up areas.