Chart Conversion Utilities

C_wiz has a "lowest common denominator" approach to the sourcing of chart images to act as visual cueing aids or backdrops in the C_wiz Map subsystem. The advantage of this approach is that C_wiz charts can be sourced from almost anywhere.

This simple approach has 2 files associated with each C_wiz chart:

o A background image (*.img) which contains the graphical content in a bitmap, run length encoded bitmap or jpeg format.

o A world file (*.cht) which is a small human readable text file which contains information such as the corner latitudes and longitudes of the associated background image.

To simplify the creation of these files a number of chart conversion utilities are supplied in a separate download, (see Download for further information).

The utilities install as C_wiz habitats, once installed all the user has to do to access them is launch C_wiz then click [File] then click [Habitats] then click the utility of choice. Each utility is fully integrated with Test Drive, a comprehensive context-sensitive on-line help facility which explains in detail the options available to the user at any point.

The utilities available are:

o [Chart Converter - GeoTiff] converts GeoTiff files into C_wiz charts.

A GeoTiff file is a tiff file with embedded georeferencing information and has a *.tif or *.tiff file type. There are several sources of GeoTiff files including the Australian Hydrographic Service  for charts of Australia (website: http://www.hydro.gov.au/seafarer/geotiff/geotiff.htm).

The utility extracts the georeferencing information and graphical content,  transforms the georeferencing information to WGS 84, massages the graphical content to the user defined projection and size, tiling if required, then creates the C_wiz chart world file (*.cht) and background image (*.img) as either a bitmap or jpeg.

o [Chart Converter - NOAA BSB 2-3] converts KAP files into C_wiz charts.

A KAP file has graphical content and embedded georeferencing information in the BSB format.

The utility uses the NOAA BSB Chart Reprojector utility to perform basic KAP file to *.tif/*.tifw conversion then massages the graphical content to the user defined projection and size, tiling if required, then creates the C_wiz chart world file (*.cht) and background image (*.img) as either a bitmap or jpeg.

The NOAA BSB Chart Reprojector utility was designed to read the BSB format (version 2) NOAA charts and therefore only recognizes for input the four map projections defined for version 2 (Mercator, Transverse Mercator, Polyconic and Lambert Conformal Conic).

There may be distributors of images in BSB format that are in other projections which the NOAA BSB Chart Reprojector utility will fail to read.
Version 3 BSB charts will read without a problem as long as they are in one of the original four map projections. This should include all NOAA charts.

KAP files can be obtained from several sources including:

o National Oceanic and Atmospheric Administration (NOAA) (website: http://www.nauticalcharts.noaa.gov/mcd/Raster/index.htm then click the [Download Free RNCs] link) for charts of the US and its possessions. These charts are free and are reasonably guaranteed to convert successfully.

o Maptech (website: http://www.maptechnavigation.com/water/digitalcharts/

index.cfm?infopg=buy) for charts of Brazil, Canada, Caribbean, Mediterranean, Mexico and Central America, New Zealand and the Pacific Islands, South Africa, UK and Ireland and Western Europe. These charts have to be purchased and may be encrypted. There is no experience with these charts and consequently no guarantees as to whether they will convert correctly.

o Federal Publications Inc (website: http://www.fedpubs.com/mpchrt/charts/chscd.htm) for charts of Canada. These charts have to be purchased and may be encrypted. There is no experience with these charts and consequently no guarantees as to whether they will convert correctly.

o [Chart Converter - Scan] converts scan files into C_wiz charts.

A scan file is a file created by scanning a paper chart. Before scanning make sure you are not violating any copyrights. If you do not have appropriate scanning equipment look for a scanning bureau in your local telephone directory.

The format of the scan file can be bitmap, jpeg or tiff/geotiff.

The utility prompts for georeferencing information in the form of the geodetic datum of the original chart and a minimum of 3 ground control points,  transforms the georeferencing information to WGS 84, massages the graphical content to the user defined projection and size, tiling if required, then creates the C_wiz chart world file (*.cht) and background image (*.img) as either a bitmap or jpeg.

Although not preferable, the scan file does not have to be a perfect scan - it can be skewed, misoriented and locally distorted. These sorts of issues will be corrected during the warping phase of the conversion, using the ground control points. The poorer the quality of the original scan file the more ground control points that should be used.

o [Chart Converter - Trim] trims C_wiz charts by removing unwanted material outside the borders of C_wiz chart background images (*.img).

The utility prompts for border definition information, searches for borders, allows the user to accept or reject the borders found then, if accepted, trims the C_wiz chart background image (*.img) and appropriately adjusts the associated world file (*.cht).