I'm making a surface out of contours. The problem is the contours have the elevation listed under object information, not geometry (the contours were brought in from a GIS file, which I do not have access to, or I would bring them in again with the elevations properly assigned, this is not an option). How can I quickly change the geometry elevation property to match the miscellaneous property?
The old school method is to use a Map Query. The way it works is you set up a blank dwg, attach the source file with the contours and configure an Alter Properties query to apply the elevation field to elevate the contours. It's a bit too detailed to spell it out step by step here but I am sure there are several posts and blogs about how to do this.
Try searching for Map+contour+elevations
P.S. Though you don't have the original GIS files, you can always export to a shapefile and re-Import using the proper settings to elevate the contours. You might also look into the extensions for C3D, one of which is a tool for creating a surface from GIS files.
see the attached - what you want is a minor variation of something I posted for another user around the start of the year.
start a new drawing. attach the first drawing with the contours with object data. use drawing query & alter properties during query to adjust to elevation.
update the posting if you need clarification, or mark as "accepted as solution"
You can always export the contours lines out to SHP format and create the attributes needed from the OD. Then use the create surface from GIS data tool. No need to do a map attach and query in a blank dwg.
Other options are to use the 2D to 3D contours Conversion tool in the UKIE pack or download the Sincpac (free edition) and use the ElevatePolylines (CHELEV) command (this give more options than the first mentioned)
Access a broad range of knowledge to help get the most out of your products and services.