CoGIS platform. How it works.

Preamble

CoGIS platform is provided for publishing and co-operative work with geodata via web browser and mobile application. One of the distinctive features of CoGIS platform is the ability to perform various operations such as creating thematic web map applications, managing access to data, applying tools for spatial analysis, importing and processing of data, generating reports and preparing statistics as widgets without resorting to classical programming.

The platform is developed based on the open architecture, which allows you to integrate its components to the existing IT infrastructure of any organization or enterprise almost unrestrictedly.

The geodata can be stored in DBMS as PostgreSQL or MSSQL without additional convertors, which means that for publishing data in CoGIS, the ready-made databases can be used, including the possibility to edit this data by means of CoGIS platform. The raster data is also supported in CoGIS.

Before publishing, you need to prepare your geodata, i.e., to set the rendering style, to specify labels, to establish connection with reference books for attributes, etc., that is, to create a map project. The map project creation is done using the free desktop software QGIS, which files can be directly read with CoGIS without any additional processing. Besides this, the ready-made maps in KML/KMZ, CMF2 formats, as well as data in GeoPackage format or shapefiles can be used for publication.

The next step is publishing of prepared map projects as web services and creating cartographic applications based on published web services. GIS server supports OGC and AGS standards which allows you to integrate the published map services to other systems. At this step, GIS administrator sets up the available protocols and operations, the rights to access and edit layers and objects.

The published maps are displayed as a hierarchical catalog and are available both in CoGIS web portal and in mobile application CoGIS Mobile.

Geodata

The platform functionality is provided to solve various tasks related with storage, publishing and getting access to geodata.

The core of any geoinformation system is vector and raster data:

• Vector spatial data – in most cases these are tables with objects, which attributes and geometry are described by the vertices. Such tables are called feature classes. The geometry types are point, multipoint, polyline and polygon. If needed, in each geometry vertex a Z coordinate can be defined. The geometry coordinates are specified based on the selected coordinate system (either geographic or projected). As a rule, the vector data is stored in the database, for example, PostgreSQL/PostGIS or MSSQL Server. The objects can be also stored in the data exchange formats (for example, shapefile) and in the local file storages (for example, GeoPackage). Besides the spatial data, in the storage there can be also the table data as reference books or other not georeferenced objects (agreements, list of contractors etc.).
• Raster data – as a rule, these are orthophotomaps, in particular, satellite images or drone photos. The most popular raster format is GeoTIFF.

All the above mentioned formats and other more specific file and data formats are supported in CoGIS. The list of supported DBMS and file formats can be extended upon request.

Management of the database scheme is done via administrative consoles (pgAdmin for PostgreSQL/PostGIS, MS SQL Management Studio for MS SQL Server), and the main functions are also available via the free desktop application QGIS.

Map projects

The geodata describes attribute and spatial properties of the objects but does not describe how to display this data. One and the same feature class can be used in different maps with different modes of data display and representation, including:

• Displaying objects on the map
  
  • Objects coloring, including coloring by unique values, by values ranges, etc.
  • Object labels
  • Visibility scale ranges
  • Default visibility of objects
• Data representation
  
  • Object name template
  • Fields aliases
  • Hidden fields and changed fields order
  • Reference books for fields with specified pair ‘code-value’
• Objects filtration (as a rule, by predefined SQL condition)
• Name of objects selection.

A collection of spatial features related to one feature class within specified territory is called a layer. The layer-by-layer representation of data is the most popular method of organizing spatial data in geoinformation systems. Based on the graphic data storage method, the layers types can be vector, raster, topography, etc.

A map project is a hierarchical set of layers with the following additional information:

• Coordinate system used for the geodata rendering (if needed, with the on-the-fly transformation from other coordinate system of the feature class)
• Attribute relationship between objects from different layers
• Metadata (author, description, key words, etc.)
• Spatial limitation of visibility area for all layers.

Integration with QGIS

The platform is developed based on the open architecture, which allows you to integrate its components to the existing IT infrastructure of any organization or enterprise almost unrestrictedly. To extend the options of work with map projects, CoGIS supports integration with the free desktop solution QGIS, which allows you to publish the created and saved qgs/qgz file via drag&drop operation.

In the map project, both vector layers (PostgreSQL, MSSQL, GeoPackage, Shapefile), and raster layers (GeoTIFF) are supported. At that, installation of QGIS software on the server is not required, as qgs/qgz files can be read directly.

By publishing, all general project settings are preserved: layers hierarchy, coloring type (symbology, clusters, heat map), labels, visibility scales, time layer settings, fields settings (visibility, order, aliases, domain/reference books, editability), coordinate systems and transformations, etc.

As the additional options for designing your map project, that are not supported in QGIS, it is possible to specify variables for layers and the whole project. This can be definition of subtypes, monitoring data about the author and the method of object’s creation or editing, extended clusterization options (pie chart, independent calculation by different regions, etc.), using pseudo-3D mode for buildings and other polygon objects, heat map with interpolation between points, semi scale dependance (when the symbol size increases by zoom but not linearly as for the classic scale dependance), mask layer for cropping image by the polygon, etc.

Map services

The ready map project should be published to provide web access to other users. Publishing of the map project file is done on the GIS server. As the result of publishing, a map service is generated, that uses GET/POST web methods to obtain information about it.

The following parameters are set at the GIS server level:

• The access rights for each service – unlimited, for all authorized users, for authorized users from selected groups
• Available protocols - OGC (WMS, WFS, WMTS, TMS) and ArcGIS Server REST API
• Available functionality – generation of map image by specified extent, generation and output of tile cache, objects identification, searching for objects, etc.

CoGIS platform has its own GIS server eLiteGIS, which, in turn, has web application eLiteGIS Manager, provided for system administrators and services publishers. Using web application eLiteGIS Manager, it is possible to publish and update map services and also to specify access rights and functionality of services.

Interactive maps and map applications

The map services are available via REST API and do not have user interface. For work with services, you will need the interactive map which is generated from one or a few map services. In CoGIS, the interactive map is set in CoGIS Designer via web interface and can be shown to users:

• As a web page of CoGIS geoportal
• As a branded mobile app for Android and iOS devices developed based on CoGIS Mobile application.

The interactive map provides the following standard tools and controls:

• Map pan/zoom
• Managing layers visibility
• Selection of basemap
• Objects identification by click on the map
• Single line search for objects by attributes
• Viewing attribute table of layers
• Editing objects.

CoGIS platforms introduces a large set of ready-made tools and functions, when configured and implemented, the interactive map can be called a fully functional map application for solving various business problems, for example:

• Visual map analysis using data coloring and filtration
• Generation of statistics on map data
• Generation of word/excel reports by data or by selected object
• Using geoprocessing tools via running geoprocessing services on GIS server for data analysis, calculation or specific editing
• Importing and exporting data.