Historic elevation data?

[Blutorse4792]

[FONT=&quot]I’m out of my element here, so forgive the potentially dumb question, but is it at all possible to somehow generate elevation data from historic surveys, in TransDEM or otherwise?[/FONT]
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[FONT=&quot]I ask because the DEM data for the area I’m modeling contains many cuts and embankments from postwar highway construction that have drastically altered, if not completely obliterated former railroad rights-of-way.[/FONT]

 

[johnarran]

Yes you can do it with TransDem if you have an historical map. What part of the world are you doing?

 

[Blutorse4792]

Generally speaking, the Midwestern United States.

 

[wayneshorter1965]

As far as I know the elevation data we have access to is based on imagery that was collected from the 1980s onward. The only info you're likely to find will be in the form of historical orthophotos or topo maps that would show the location on a plane but wouldn't provide any 3d height information. In theory you would use this information to sculpt in the cuts where you want them.

 

[Blutorse4792]

I suppose I was hoping there might be some way to generate 3D terrain from historic topographic/relief maps. As it stands, I'd almost be better off with a less-detailed DEM that excluded manmade geography.

 

[gawpo50]

I suppose I was hoping there might be some way to generate 3D terrain from historic topographic/relief maps. As it stands, I'd almost be better off with a less-detailed DEM that excluded manmade geography.

On the USGS servers are historical topo maps dating from the late 1950's onwards. I use them all the time.

 

[Blutorse4792]

Indeed, I actually have a collection of topo maps from the 1920s through the 1940s. To clarify, the issue is that the DEM itself includes cuts and embankments which were dug out for highway construction decades after rail service ended. Worse still, there are a number of crucial locations where this earthmoving has irrevocably altered the right-of-way of the rail line I was attempting to model, and it's just not feasible to level it all out by hand.

I was hoping that perhaps there was some way to generate the terrain itself from historic elevation data, either from older (pre-highway) maps or some other source, but this does not seem to be the case.

 

[Shortline2]

You can sculpt the landscape from Topo maps by hand, in TransDEM, but it is not as easy as I wish it could be, when it comes to do it partly on a existing DEM .

I've done it years ago for Cripple Creek, Colorado, but never got as good as I wanted and the DEM for that area has issues already so all I say here is old info but the tools are still there in TransDEM.

I used to use another DEM program before, that gave me access to the numbers making up the DEM info in a sort of table format and I could change in that table where I saw clearly numbers out of range.

In TransDEM I need to use sort of lines drawn in and those get worked into the DEM by TransDEM itself in a way I never fully understood and with all the issues I had fixing in a 1906 scanned topomap into a modern world the project of mine stalled.

But, there are tools in TransDEM to try help you with what you ask about.

Linda

 

[clam1952]

I've sculpted a current lidar dem to 1930s in surveyor, tedious and require patience removing raised highway embankments etc, hardest bit was recreating the valley flooded by a reservoir, done by using old Ordnance Survey maps and photographs where possible. Old maps with Contour lines help!

 

[JCitron]

It's heartbreaking to see the damage done by highways, dams and development that has wiped out what could have been a successful rail line. Not long ago, I imported ca. 1943-44 topographic maps on to a modern DEM and then rebuilt some areas using the old-fashioned spline on the terrain to smooth things out.

In one location, a gravel company moved in and physically flattened the side of some good-sized hills. This can be seen when overlaying the topographic map on top of the hill. In another location I restored a river valley that has been wiped out by a dam put in during the mid-1920s. The 1943-44 topographic maps still showed the railroad ROW and the hills even though the underlying terrain has been zeroed out at 450 feet (140 meters). Using the topographic height lines and splines, I was able to restore the valley pretty well. I now need to go through and smooth things out.