Creating a large landscape with accurately varied elevations I am teaching a Blender class and my advanced students are animating a scene in Charleston Harbor set during the Civil War.  Since I am a CAD guy, creating a scaled version of a harbor chart using AutoCAD and Inventor was easy for me but creating a varied elevation was not.  I extruded the landscape to an elevation of 20 feet it is  flat.  I'd like some help finding an easy way to give the mesh a varied height based on the harbor chart shown below.  I plan to use the chart as a texture over everything.

You can find the text I am using at http://www.cdschools.org/cms/lib04/PA09000075/Centricity/Domain/81/BlenderBasics_4thEdition2011.pdf.  On pages 32 &amp; 33 of that text it shows a process similar to what I have in mind that divides a plane into squares and changes the height by selection and movement of vertices upward.  That would work for this but I don't know a way to make an accurate measurement of  height for movement of a mesh as large as the one I am using (8 x 10 nautical miles).  One can scale an object by typing the scale factor.  Can I move vertices up in that manner?

Is there a way you can show me that allows me to paint height areas rather than to drag them up?  It would be great if I could add the harbor chart over the land areas as a texture and use it as a guide for changing the elevation of pertinent areas.
A map with 3D elevation can be generated from images.



In Blender 2.76, here is a workflow for generating elevation maps.


Obtain elevation data as an image. For example, potential sources are http://viewer.nationalmap.gov/basic/ , http://eros.usgs.gov/elevation-products , or http://earthexplorer.usgs.gov/ .
Import the image as a plane. This may require enabling the 'import as plane' add-on.





Go into edit mode and subdivide the plane lots of times - 10 to 16 times works well. The more times you subdivide, the finer the elevation will be, but the slower blender will respond.





Apply the displacement modifier to the plane. Choose the image that was imported as the texture.
Adjust the displacement modifier to get a good scale for the displacement.





For some visual effects, in Blender cycles, a color ramp can be used to color based on the altitude.






A blend file with a south-east use map imported is here: