This is the process of relating the grid positions of the bitmap pixels to their corresponding latitude and longitudes. In many parts of the world, particularly in North America, there is more raster data available. This is not always the case, however. At the current time, this is usually the key factor in deciding which type of charting system can be used. If a system does not read the format of the local data, it is more or less useless.
Some regions require a system to use multiple data formats for full coverage.
It is generally agreed that vector data based systems offer the navigator greater utility, as described above. Presentation Many navigators simply prefer the look of raster charts. They are usually direct copies of official hydrographic office charts. This factor usually diminishes the more familiar a navigator becomes with electronic charting systems, but there are still some who strongly prefer raster charts. Performance Even though vector chart files are often physically smaller than their raster counterparts, they generally consume more computer processing capacity in order to interrogate and draw each data object and layer separately.