Where is the dam? City, State, nearest major road intersection? What is the name of the topo map? What's is the map's source? Can you paste a link or the topo map itself?
In order to 'match' Google Earth (or Bing aerial imagery) you need two things:
- Your topo map must be georeferenced when you bring it into Map 3D. If you map contains geospatial info, then it will know where to position itself in your map. (Imagine the modelspace represents the surface of the Earth. Your map must know where to go with respect to the equator and North Pole, otherwise your topo map may end up in the middle of the ocean.)
- You will need to assign an appropriate coordinate system (CS) to your map. Appropriate means the CS must be applicable to your area. You can't assign a Florida CS when your map is targeting California.
Typically, topo maps, such as those downloaded from the USGS are in UTM. Your modelspace, however, can be in State Plane Coordinate System (SPCS). Map 3D will transfrom the topo map's geo-reference, the map's UTM, to your map's coordinate system or assigned SPCS.
BTW, you'll get more traction in the Map 3D forum, not this one.
Chicagolooper
