Top50 OVL (.ovl)
A Top50 OVL file is a plain-text overlay of waypoints, tracks and routes for Geogrid-Viewer, the map-viewing software bundled with Germany's and Austria's official Top50 (1:50,000) topographic map CDs/DVDs.
At a glance
| Extension | .ovl |
| Encoding | text |
| By | EADS (Geogrid-Viewer) |
History
Top50 OVL is the ASCII variant of the overlay format used by Geogrid-Viewer, mapping software from EADS distributed with the Top50 topographic map products sold by the German and Austrian state surveying offices (Landesvermessungsämter). A separate, undocumented binary OVL variant also exists in several proprietary sub-versions; only the published ASCII format is covered here. No specific introduction date is documented.
Where it is used
Geogrid-Viewer overlays user waypoints, tracks and routes — including ones imported from a GPS receiver — onto the Top50 map background; an OVL file is how that overlay data is saved and exchanged. GPSBabel also reads and writes the ASCII variant, and third-party mapping tools that support the Top50 map format (such as QuoVadis) can import it as well.
Structure
A plain-text, section-based (INI-style) file: one [Symbol N] section per point or line, each with a group number, a Typ (element type such as point, line or area), display properties (Col, Zoom, Size, Art) and a list of decimal-degree X/Y coordinates; an [Overlay] section recording the total symbol count; and a [MapLage] section carrying the underlying Top50 map's name and center coordinates.
How widespread
Tied to Top50, a specific German/Austrian official topographic map product distributed on optical media rather than any current online service; files in this format come from that CD/DVD-era Geogrid-Viewer ecosystem.
RouteConverter support
| Reads | Top50 OVL ASCII |
| Writes | Top50 OVL ASCII |
RouteConverter reads and writes Top50 OVL ASCII files, including multiple routes/tracks per file; per GPSBabel's own documentation, very large ASCII OVL files (many thousand points) are known to cause loading errors in Geogrid-Viewer itself, a limitation of that program rather than of RouteConverter.