Dr. Ziegler, I apologize for the delay in responding to your questions.
I transfer information from the USGS topo maps to Trainz baseboards by means of a Blender intermediate. I make one (or, when necessary, more) collages from screenshots of the topo maps, and using the scale, determine the size of a 720 m x 720 m Trainz baseboard. From that information I construct a baseboard grid which I overlay on the image collages I constructed. This allows determining the best location for the baseboard divisions. Then I create a second baseboard grid subdividing the 720 x 720 Trainz baseboard into 72 10 meter (or 144 5 meter) divisions on each side. From top view (obviously, orthographic mode) I trace the major terrain elements, including contour lines and water elements; railroad and highway rights of way, superimposing them onto the 10 m square grid. In practice, the majority of information comes from the topographical maps. Google earth is mainly used in some cases where I want to access older imagery than is available in some of the current crop of TOPO maps, and to verify information about which the TOPO map is ambiguous. An example of this is a stretch of roadway that I know to not be flat, but where the profile is not accurately reflected by the Topo map, because the stretch of roadway in question does not cross a contour line. In the particular area I am working with, the contour lines are on 10 foot separations, but some of the maps I have used in the past have included 20, 40, 50, 100, and 200 foot separations between the elevations of adjacent contour lines. Contour lines are traced into the blender as a edge object, where there is a vertex placed at each point where a contour line crosses a grid line. When all of the elements are created for each baseboard area, they are filled in, and the objects are exported to a 720 x 720 baseboard form, and the grid of the baseboard is raised or lowered to the form of the baseboard form created in Blender.
Now, I concede that the intermediate step of creating a Blender object of the baseboard area is not strictly necessary. One might, instead, simply divide the collages into baseboard sized images, and import these images into Trainz for use in raising elevations to contours there. I don't advocate this for two reasons. First, by using the intermediate Blender form, I gain the advantage of rotating the baseboard, useful if I have a route oriented along a North / South axis, but which I want to use on an East / West, West / East, or even South / North axis. Second, when raising elevations in Trainz so that the of the terrain is more than about 1 unit vertical to 2 units horizontal, I find the distance between grid squares to be unsatisfying. In these cases, I can use the Blender form to create terrain with vertical separations closer to the 10 meter separations in the horizontal. Of course, this terrain is created and handled like scenery structures, but I find the overall effect to be superior to what can be achieved in Trainz. This is perhaps most easily demonstrated with an image. The bit on the left in the image below is the landform generated by Trainz; the landform on the right is a Blender object constructed from the elevations of the structure on the left, but with additional geometry to provide a 10 meter separation between adjacent contour lines that more nearly matches the separation between the horizontal baseboard lines of the Trainz land form.
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