SEMObowhunter wrote:I graduated from College with a degree in Surveying and worked in the field for five years before starving out. Land is measured, bought, sold, etc. by the horizontal distance. This does not include elevation calculations. Basically you are looking at a flat plane with an elevation of zero. Land can be surveyed with elevation (vertical distance) but this is only used for topography. On a boundary survey you measure with X,Y coordinates, whether GPS or made up and these are just northing and easting coordinates. Elevation is measured with X,Y,Z coordinates. This gives you the northing, easting, and elevation on any shot taken. The topo maps we all use are generated from an airplane flying at a certain altitude, certain speed, and using a lens with a set magnification. They fly over the area taking pictures that overlap, these are then overlaid onto a map of the area, where known elevations with GPS coordinates have been located.
I did some aerial topo support for aircraft on a 300 square mile stretch along the Missouri River in central and western MO for the Omaha District of the Corps of Engineers. We had a grid of the whole area laid off in 3 mile by 3 mile grid and we located certain points on the ground, then the plane flew the whole area and they compared their data to ours. This was for an update to some top maps of the River levees and the surrounding area.
The construction company I worked for in Montana had the up keep and remodel contract for the federal buildings for awhile. While doing a little job in the Forest Service Cartography quarters. I got to see these dual aerial photos. For just basic overveiws they had this binocular magnifying glass thing. When you looked at the photos through these things looked 3D. Of course for map making they had a special camera set up with a special computer program.
Totally fastinating though. Same program as was being used for smart bombs.
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