Concept

Below each decision, open discussion on features is presented. Your contributions are welcome.

WikiPedia has a short article on Thuban in German.

Programming Language

Thuban is implemented using the Python programming language. Python has been choosen as a multi-platform, object-oriented scripting language that allows simple incorporation of modules written in other languages (e.g. computational intensive tasks in C). It is taken care that Thuban is compatible with Python 2.2.1; newer versions should work as well.

As a multi-platform GUI toolkit, Thuban uses wxPython. wxPython is based upon wxWindows, a GUI toolkit that uses a platform's native GUI to embed consistently into the users system (i.e. GTK on Linux or Microsoft Windows NT). Thuban requires wxPython of at least version 2.4.0.4. It is taken care that Thuban is compatible with the latest release of the 2.4 series; newer versions should work as well.

Data Types and Formats

• Line
• Polygon
• Point
• Georeferenced Image

We do not intend to develop new software for reading GIS files in various formats. Instead Thuban will only support formats for which adequate libraries are available. The initial releases use Frank Warmerdams Shapelib and thus can handle the Shapefile format only.

The shapelib is to be substituted by the GDAL / OGR library for a broader range of vector and raster formats.

Thuban will connect to databases, e.g. the GRASS database and PostGIS.

Simple add-ons for and whole applications based on Thuban

We think that extending Thuban via Add-ons is a good alternative to directly adding features to Thuban. It allows you to add some specific elements you need for your work. It even is possible to create your own custom applications with all the features of Thuban without the need of forking the development and maintaining your own branch of Thuban.

One example for a comprehensive extension of Thuban is GREAT-ER. It is a environmental simulation tool for chemical exposure in river networks.

It is possible

• to add additional menus to the menu bar
• to add additional menu items to existing menus
• to add tools
• to store additional information in the xml-based session

Session storage

The routine to read/write a .thuban-file are kept central in Thuban/Model/load.py and Thuban/Model/save.py. We've decided against distributing the knowledge how to write each object with the object itself in order to better maintain different versions of the file format and different file formats in general.

Some features are not too easy to decide on. Please feel free to contribute to the following feature discussions (or even raise a new one).

• Handling of Cartouches (North Arrows)
• Multiple Maps in One Session
• String Encoding and i18n
• The Edit Menu
• Tool Activation via Menu

Featuring a northarrow very much reaveals the same problem as a scalebar.

Currently a session contains only one map to work with.

As brought up by Evgeny Cherkashin, it is desirable to handle other encodings than latin-1 (like russian encoding).

As first steps, Thuban should support i18n and should be made unicode-clean.

The question on how to handle filenames best remains open.

The Edit Menu

Many programs offer an "Edit" menu where general edit opportunities are summarized. Users get used this though it does not make sense in some cases. We think that Thuban should have one.

Currently Thuban allows the activation of tools either via the toolbar or via the menu. Once selected, a tool is active until another one is selected.

It occured in a discussion that it might make sense to have the menu-way select a tool for exactly one action and then return to the previously active tool.

2004/11/03