O.K. so WHAT are NED BIL files and why are they so great?

Well, for many years the DEMs that were available were primarly all 30 Meter in resolution. And then a few years back the much better 10 Meter resolution dems became available. The difference is AMAZING! But the file sizes are obviously about 3 times (or more) bigger.

And then the guys that do this stuff for the US Govt. came out with the NED format- which are SEAMLESS terrain chunks- saving LOTS of problems in matching up terrains side-by-side- especially nice when you are doing something like the Grand Canyon. But of course NED files can be HUGE (and I mean HUGE!) One method to make them smaller is storing them in Binary format- one being the BIL format. Still HUGE, but more managable.

MICRODEM can read HUGE 1 gigabtye NED BIL files that even WILBUR will choke on. And Microdem can be used to slice these NED's up into smaller sections and saved out. THIS is where my Mt. St. Helen's file came from- a HUGE chunk of Western Washington State where I zero'ed in on. You can get chunks of Arizona and save out the Grand Canyon- or UTAH chunks and save out Monument Valley or Bryce Canyon. The resolution you will get is well worth the effort if you like VAST TERRAGEN type renders.

Of Course- you can also find a lot of these files already in TER format- which is why that is another very good option for getting near-ready-to-use terrain data- following the Terragen--2-Vue Method...