Better nautical chart images coming to electronic charting systems

Things are changing for U.S. nautical charts. We think you’re really going to like this improvement!

The NOAA RNC is a geo-referenced digital image of the traditional paper chart. When it comes to digital graphics, higher resolution is generally better than lower resolution. Dots per inch (dpi) measures the image resolution: the higher the dpi, the better the resolution, the clearer the image. Today, cartographers at Coast Survey are busy improving the resolution of NOAA RNCs, increasing the chart images from the current 254 dpi to 400 dpi. This change improves the clarity, readability, and aesthetics of this highly popular digital charting product.

Coast Survey maintains over a thousand RNCs that are available as free downloads. Our Marine Chart Division is transitioning the entire suite, updating and checking quality on all the charts, and we expect all RNCs to be upgraded to the 400 dpi by January 2014. Don’t worry, we aren’t taking anything offline. You won’t even notice that we’re changing the RNCs, except that you’ll see clearer images after your chart has been changed to 400 dpi.

RNC screengrab at 254 dpi

RNC screengrab at 254 dpi

RNC screengrab at 400 dpi

RNC screengrab at 400 dpi

This improvement in RNC clarity will make it easier and faster for mariners to interpret the information on the chart. Less time puzzling through ragged graphics means more time to increase situational awareness.

We’ve included a 400 dpi test dataset on the NOAA RNC webpage, so RNC users can give it a try. The test dataset includes BSBs for Detroit, Long Island Sound, Puget Sound, and Tampa Bay. We hope that users and developers will let us know if you discover any problems with the test dataset. (Submit comments here.) We’ve listed some frequently asked questions below.

FAQs

Does this change the actual format of the RNC? No. The only change is the resolution of the chart image.

Will higher resolution files have bigger file sizes? The average increase in file size is around 50 percent, but that is easily handled by today’s computers, mobile apps, and display systems.

When will all the high-resolution RNCs be available for public download? If the transition goes as planned, NOAA expects to upgrade all RNCs to 400 dpi by the end of 2013.

I currently use the NOAA RNC suite in my chart plotter. Will the high-resolution RNCs work as well? We expect no compatibility issues in this upgrade. If you do have technical problems with this upgrade, contact your software provider for technical assistance. We encourage software providers to let us know of any difficulties during the testing period. Submit comments and questions to NOAA’s Nautical Inquiry & Comment System.

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