Qt Virtual Chart Table (QVCT) - Frequently Asked Questions

General Questions

Map-related Questions

Device-related Questions

Usage Questions

General Questions

On what platforms does QVCT run?

Currently only Linux. However, being based on Qt, it can theoretically also be compiled for Windows and Mac (or any other platform supported by Qt). QLandkarteGT is a similar open source project that actually supports all formentionned platforms.
Patches to enable QVCT support of new platforms are of course welcome!

Thanks to Olivier Bornet and Samuel Gaist for their contribution to Mac OS X support; Qt, GDAL and GPSD dependencies are readily available as part of the MacPorts project.

How big a project is QVCT?

Excluding blank and comment lines, QVCT totals ∼25'000 lines of C/C++ code (25 KLOC).

Who is behind QVCT (and why)?

I - Cédric Dufour (System and Software Engineer) - am the sole developer of QVCT. As a Linux evangelist, I had become fed up of switching to Windows to perform the navigation planning required by my private pilot activity. Additionaly, I wanted to have a touchscreen-friendly and ergonomic navigation software to use on my (Linux) tablet while under way.

Besides, using a PC to perform navigation tasks while in the same time holding the commands of an airplane or a ship raises several issues which I found weren't properly addressed in other existing (open source, Linux-compatible) software. Among those issues are: use your own (offline) maps (e.g. ICAO or marine charts), provide a clean and efficient user interface (suitable for a moving environment and a fast achievement of tasks), track multiple vessels, using multiple devices (GPS, compass, IAS/loch, pressure altimeter, etc.) for your own vessel (thus being able to distinguish between its true and apparent course), etc. QVCT answers those requirements (at least from my point of view).

Map-related Questions

Are maps provided along with QVCT?

No. You must create/use your own maps.

What kind of maps can I use in QVCT?

Theoretically, any image/file type supported by the Geospatial Data Abstraction Library (GDAL). In practice, you will most likely want to use GeoTIFF files, which are the most common geo-referenced files.

Can I create my own maps?

Can I use elevation data along with maps?

Yes, absolutely! Digital elevation models (DEM) can be converted to a geo-referenced file the same way as maps. They can then be associated to any map (and then even displayed) within QVCT.

Can I use online maps?

How big can maps be?

On recent hardware, maps can be as big as 100-200MB, the Geospatial Data Abstraction Library (GDAL) being very good at working with large files (at least in GeoTIFF format).
I personally have maps of all Switzerland at 1:500000 (ICAO) and 1:200000 (topographic) which weight respectively 30MB and 120MB and which I use daily on an Intel Core i5 2467M tablet.

What is this georeferencing and GDAL all about?

Device-related Questions

What navigation devices are supported by QVCT?

To start with, any device that is supported by the GPS daemon (GPSD), used either as a GPS (single vessel localization) or AIS receiver (dynamic flotilla).

Also, any device that sends Kinetic Avionics's SBS-1 data over the wire may used used as ADS-B receiver (dynamic flotilla).

Can I create my own device?

Yes, provided you have some knowledge of C/C++. The source code of QVCT includes a SAMPLE_DRIVER example that should allow you to create your own device in a matter of minutes (if the device's protocol is simple enough). To give you a clue of the task at hand, each GPS daemon driver (GPS or AIS mode) is less than 400 lines of code.
Please refer to QVCT's Developer Documentation for further information.

Is there any ADS-B (SBS-1) hardware for Linux?

Usage Questions

Why do landmarks get aggregated when saved in GPX format?

The GPX format does not provide a way to gather landmarks (GPX waypoints) in distinct containers. Thus, when landmarks are saved in GPX format, they are all gathered in the same "pot".

Are file formats other than GPX and QVCT (XML) supported?

No, not directly. On the other hand, one can use the gpsbabel utility to convert from/to the GPX format to/from most of the other existing file formats.

What are dynamic flotilla?

QVCT provides two way of managing vessels: either individually, by manually creating each vessel (and optionally associating one or more navigation devices to it for geo-localization purposes) or by associating a device to a flotilla, in which case it becomes dynamic, meaning that vessels will be automatically created (and geo-localized) as data appear on the device's wire.

Why have multiple devices for a single vessel?

The idea actually comes from the marine world, where several navigation devices are available (GPS, compass, loch, depth meter, etc.) and (potentially) linked together - usually using the NMEA 0183 protocol - to provide information in an integrated environment.

In QVCT, provided you do have several devices available, this allows in particular to distinguish the ground course from the apparent course (thus indicating the presence and importance of drift wind or current).