OkMap is described as 'interactive software which allows you to work on your computer screen with web maps or digital maps that you have either bought or scanned' and is an app in the Travel & Location category. There are four alternatives to OkMap for Mac, Windows, Linux and Online / Web-based. The best alternative is Pix4Dmapper, which is free. Other great apps like OkMap are WebODM (Free), MapTiler (Free) and Polymaps (Free).
MapTiler is graphical application for online map publishing. Your map can create overlay of standard maps like Google Maps, Yahoo Maps, Microsoft VirtualEarth or OpenStreetMap and can be also visualized in 3D form by Google Earth.