When visualizing ECDIS data, it can be that:

  • Only the bounds of a cell are shown, instead of its contents

  • The cell contents is shown but covered with a hatch pattern of lines

This is the over and underscale protection mechanism that you see. Each ECDIS cell was designed to be visualized in a specific scale-range:

  • When zoomed out: if all data would be shown, the application would run out of memory. Therefore the bounds of the cell are shown instead of its contents.

  • When zoomed in: the data might not be precise/accurate enough for that zoom-level, resulting in for example missing objects. To make the user aware of this, the cell contents is covered with lines.

This behavior can be turned on/off on the TLcdS52DisplaySettings class: see the setDisplayOverscaleIndication, setDisplayUnderscaleIndication and setUnderscaleIndicationColor.

ecdis bounds only
Figure 1. When zoomed out, only the bounds of the cell are visible
ecdis overscale
Figure 2. The hatching indicates you are zoomed in beyond the accuracy of the available data