- - In the history
of raster digital nautical charts
. The old Maptech
with the "Charthdr" files are the oldest available format. In the early days scanners and computer memory systems were extremely limited. All e-charts come from "real" paper charts
or the original "acetates" (transparent plastic sheet that the cartographer actually drew on with pen and ink). It was not possible to scan the entire chart in one pass and also the size of the digital file exceeded the capacity of the computers
so each chart was divided in smaller pieces. These are the "ao1, a02, etc." files you are seeing on the CD. The e-chart programs assembled these parts
to display the chart on the monitor
. One chart consumed up to 6mb or more storage
space and had to be brought into the e-chart display program in little pieces as the amount of memory was limited.
- - The next generation of e-charts was the BSB
format where they were able to reduce the file size dramatically enough to get all of a chart into one file of - on average - 1mb. Still the little "side charts" to a chart were kept in separate files, these are the "_1, _2, _3" files.
- - The originals of all the USA NOAA nautical charts were made available for free to BSB
and also Maptech
under the idea that taxpayer paid for government
charts had to go into the public arena where there would be competition. However, shortly later BSB bought Maptech and that ended all competition and the prices skyrocketed. At this time Softchart started up and did not use the "Acetates" from NOAA, instead they simply purchased paper charts and scanned them. They had to change some of the original color schemes of the "normal" nautical charts to avoid copyright
and other problems. And better yet, they underpriced BSB by significant amounts of money
. All this caught the attention of some politicians in Washington
and a war ensued over the $400 prices for CD's when the charts had been made available for free from NOAA. Softcharts was the counter argument that it did not cost what BSB claimed to produce these CD's. Upshot, laws were passed that forced NOAA to make the charts available to the public for free (not really, since taxpayers paid for the original costs of surveying and producing the charts).
- - Refinements were made in the BSB format to decrease storage
space needed through BSB1, BSB2 . . . BSB4 and so on. So now prices dropped for the BSB charts - for awhile - forced by competition from Softcharts and the free NOAA download services. BSB was not very happy.
- - It was about now that "quilting" of charts within the e-chart navigation
programs was developed. Memory size was now available to hold more than one chart so they could be "quilted" together. However, the original "old" Maptech (hdr) were too huge and the programmers simply excluded this whole series of charts from being able to be loaded into their programs.
- - In a deal with the e-chart navigation
programs a new software
change was installed that blocked the use of the "free" NOAA charts. Still there was the problem of piracy
, copying of CD's. Dongles and "keys" and so forth were tried to "lock" the CD's. Finally, the disc format was changed from individual chart files to one huge continuous file that only the approved software
- - If you want to access the old Maptech (hdr) charts that I mentioned contain charts for places in strange and wonderful corners of the world, you have to retain one of the "pre-quilting" navigation programs such as Cap'n version 6 and earlier. These ancient charts are easily recognized as many contain hand-drawn palm trees and huts and are usually monochrome.