GIS and Cartography Workgroup
AVISO Geographic Information System
AVISO is mapping software with tools for data management and professional map editing. Its range of use is as wide as cartography itself and includes:
- Statistical, census, population and election mapping
- Cartographic visualization for environmental research including geology, geomorphology, soils, botany, and other fields
- Business and economic data visualization
- Decision support for spatial planning and zoning
- Topographic map production
AVISO supports a range of cartographic presentations suitable for point, line and area geographic objects. As usually in GI systems, map contents is organized into layers. Simple presentation layers have single graphic style applied to whole set of objects. Color, line width and style, text properties, fill patterns and transparency are supported. Complex presentations differentiate objects according to their data and apply different graphic styles within a single layer. For instance, objects may be grouped into continuous ranges based on a numeric variable or discrete categories based on text variable. Further, objects may be transformed from their native geometry (eg. point or area) into different presentation object like text label or diagram. AVISO supports multi-variable bar and pie diagrams with many control options.
- Vector-based fill patterns assure that maps with filled areal units will print exactly as designed on screen. They can be composed of either symbols or lines with user-defined layout, density and angle.
- Range presentations can be built on two variables simultaneously. For instance it is possible to define a rectangular matrix of colors (or any other graphics property) for income-by-unemployment presentation.
- Special kind of layer, named “clone”, is a dynamic copy of other layer’s objects with re-defined graphic style(s). This can be used to overlay additional shading pattern, drop shadows for text, build compound symbols, make inner fill for road network and other creative effects.
- Whole map can be embedded within a layer of another map.
- A ”shaded line” graphics style varies color along linear object according to lightning angle. It is suited especially well for contour lines and, provided appropriate density, turns map into 3-dimentional relief model.
As a true GIS, AVISO is built around a database system which holds all data necessary for map production. This includes attribute data (numeric, categorial or text characteristics of objects being mapped) and geometry data (shape and geographic position of objects being mapped). Conforming to well known relational database model, data is stored in tables with columns and rows, and may be worked upon directly or accessed by queries expressed in SQL (structured query language). AVISO is self-sufficient in terms of data maintenance – no external DBMS is needed and the data can be transferred between computers easily.
- SQL queries are fully dynamic, meaning the result is always up to date without user intervention. Still, data accessed by query may be edited "live”.
AVISO is vector-based system. Geometry data can be exchanged with other GI systems via MapInfo and ArcGIS import/export or digitized. Here AVISO provides a full path from paper-based source map to vector data. Scanned image is first registered and tools are available for on-screen digitizing. Finally, geometry can be checked for errors and stored in database table one-by-one or in batch. Geometries are stored independently, without building full topology structure. However, proper topological relations can be maintained with the help of digitizing tools (for example by tracking existing vector lines or simultaneous editing of objects in multiple layers).
- A tool for semi-automatic line tracing on raster image is provided to ease digitizing of lines or areal units’ boundaries.
- It is possible to digitize without knowing projection on raster map.
AVISO employs simple and radical approach towards coordinates handling: geometric data is stored and processed internally in geographic coordinates only, projections or transformations are applied automatically when needed. This way, the user is never confronted with a mix of coordinate systems in database or map and never obliged to transform coordinates for a given purpose.
Contrary to some other GIS software, which claim ”on the fly projections” and actually store projected data, AVISO silently performs projection transformation each time a map is redrawn.
Once digitized, geometric data becomes content of map and can be edited again. This cartographic editing may involve changing graphics style like color, text size, line width etc. or adjusting geometric properties like position or shape. Changes may be applied to any individual object or group of objects.
A truly unique feature of AVISO is it’s ability to maintain these modifications even after the contents of a map must be refreshed from the database. Apart from “generating” a map from a database, AVISO provides “synchronizing” procedure, which preserves manual changes during the fetch from database. This works at individual object level and individual graphics property level. It is possible then, to replace the text of the labels and keep their adjusted positions or different font applied to some of them. Diagrams can have their structure changed and remain at adjusted positions. Any special object can keep single graphics property preserved while having all other properties consistent with the database.
Many faces of AVISO
Standalone AVISO system has never been released as a commercial product, though it has been used in some public institutions. The most important use in IGiPZ was for 1:300.000 and 1:200.000 road atlases of Poland and related Digital Map of Poland. AVISO still works for us though it needs a major upgrade.
During many years of development, AVISO accumulated thousands lines of code, which become a “mapping engine” useful in subsequent projects. These include AIMS (Aviso Internet Map Server) and two transportation modelling systems: WMDT and OGAM (Open Graph Accesibility Model). It is clear that this kind of co-development is beneficial for all projects, because common GIS code is improved all the time and improvements are instantly available in all related systems. I hope one day new, modern standalone AVISO will be released again.