NEA valuation, page-64

The 1m DEM data is a 1m grid of derived ground - so a point every metre ..

You can take that data into any civil-style software and generate a digital terrain model - which can then generate contours.

Something like Civil3D, 12d, Magnet .. many others. No doubt there are freebies.

A million points per square km - for free. The data is pretty good - usually within ~ 100mm. Not everywhere has 1m coverage, but there is 5m and 30m. The 30m grid data came from the Shuttle topography mission.