Chart elements missing along sharp boundary, vague land outlines without nautical objects, or density of chart details much less than expected — Navionics charts on iNavX
Article IX14255, February 25, 2016
Different adjacent Navionics chart regions contain different levels of chart detail. Download multiple adjacent regions to avoid omissions in navigation aids, nautical objects, and depth sounding data density.
Trivial case for iNavX 5: the World Chart is not a Navionics chart
Some customers see the default basemap 00000_1 World Chart and assume that is a Navionics chart and they are concerned over the total lack of charting detail.
Of course, this is not a Navionics chart. Tap the Charts menu and, under My Charts, select an actual Navionics chart title and specific chart region.
Chart details for different regions
Customers sometimes get the impression chart details are missing or low quality because they have not downloaded enough overlapping adjacent charts. Here is an example from the Navionics 2XG collection on iNavX but the argument holds for other vector chart collections as well.
In the illustration below, only one chart region, whose title mentions "Lake Ontario", has been downloaded for viewing. As far as iNavX knows, that's the only data in the collection at the moment. When viewed in a highly zoomed out range, one can see thin red rectangles set within one another. The larger the rectangle, the more problematic the coverage situation: some areas within a given large rectangle may have, in particular spots, partial chart data or no chart data at all.
Along the fringe of chart coverage defined by red rectangles, data goes totally extinct, there's nothing more to see because the limit of coverage has been reached. In the example below, the data coverage drop off is unmistakable.
However, in some areas the data coverage situation is more ambiguous: meaningful amounts of nautical charting data is presented but the data may seem sparse, incomplete, not what would be seen on a chart plotter examining the same Navionics chart for the same area.
The issue discussed is, however, trivial. All that needs to be done is download adjacent regions. In the example given here, another chart mentions it contains the western reaches of Lake Ontario -- a bit of text that is easy to miss unless you study the chart list carefully. Downloading that second regional chart immediately changes the ambiguous data presentation situation.
Here is a partial screen capture of two regions downloaded and the resulting overview of the combined / overlapping regions...
Now the previous fringe boundary of coverage no longer applies, lots of new accurate charting data seamlessly spans the same area that previously had a sharp data boundary limit.
And the chart area that was previously sparse and generalized is now packed with many more spot depth soundings and other details.
In summary: before assuming the Navionics chart collection is missing something, download other adjacent regions that may have data overlap. This may quickly resolve any previously seen deficits.
Beyond this, two other software settings issues can sometimes lead customers to think there are charting problems when, in fact, a minor settings change fixes everything. See the related articles:
- Chart appears for several seconds, then iNavX jumps away to a featureless land outline -- Position Icon at Location function
- In a chart list, some chart regions seem to disappear, cannot see previous downloads -- About iNavX chart filter function