I learned something new the other day which is always a good thing. I was trying to figure out Civil3D for a major project at work. Fortunately there are several forums that can be quite helpful and even though I was looking for one thing, I found another. Apparently all the USGS topoquad maps are based on digital data. The maps always looked uncomputerized, being green and brown and almost having a “hand drawn” effect. Little did I know that they have a huge database of topo information, DEM files, that load straight into Civil3D creating the same contours as on the map. They also have spatially correct topoquads. All for free. So I downloaded the topoquads for the Perdido area (Barrineau Park and Seminole) and put them in a new drawing. Sure enough, they showed the correct coordinate base as Google Earth. Next I downloaded the DEM files. They were not in the right place (probably due to my not understanding something about them) but I moved them around and got them in the correct place. The problem I ran into is the parcel I’m dealing with falls on two different DEM files. Individually they look good, but together they don’t match. What’s up with that? Supposedly I can get some topo files from a NASA website but I haven’t looked yet. The big thing was getting something spatially correct with contours so I could at least get a trail on paper to submit to the NWFWMD.
So after I drew up a quick trail on the parcel, I ran it through Civil3D and created an alignment which produced points every 100 feet, just like I did in Blackwater. The trail roughed out to about 8.3 miles which is nice but I seriously doubt it will get approved as is. But the other cool thing I learned was I can convert those Civil3D points straight into a .gbd or .gpx file which goes right into the GPS or Google Earth. I was not looking forward to typing in 400+ coordinates for a hypothetical trail. GPSBabel did it instantly. I was super skeptical as it didn’t work when I ran it initially. After just giving it a file with just lat/long information, it spit a file out that worked perfectly. It was one of those “Doh!” moments. I’ll attach a picture of the layout from Google Earth for all to see.