Photogrammetry and Control FAQ's:

How do I get descriptions for horizontal and vertical survey control stations?

The P&C Unit, provides survey control descriptions at Maine Horizontal and Vertical Control Points web page with control point descriptions.  A general tutorial will be provided to assist you through the process.

FMI, contact P&CU at mdot.survey@maine.gov or at 624-3517 or 624-3493 during business hours.

Someone is pounding a big rod in the ground on the road in front of my house.  What are they doing?

Locating position for four foot rod.
Hammering rod into ground.
Point is occupied for GPS data collection.
Keith Reynolds locates the spot for setting the 4' rod and places a marked disk on the top of the rod. The rod is then hammered flush with the ground. A GPS tripod with reciever then collects data from each control point set.
     
CONTROL POINTS ARE
ALSO PLACED IN
LEDGE OUTCROPPINGS.
Drilling ledge for control marker placement.
Preparing ledge for disk.
Placing sign marker.
Jason Everett uses a Cobra to drill a hole in ledge for a disk Control Marker. Pam Locke prepares the hole in ledge with cement to hold the control disk in place. Dan Raymond places a sign marker near the point for future reference.

 

What do I do when I find a big white "X" on my front lawn?

 

Aerial Target on lawn

Our MaineDOT GPS Field Crew stategically places temporary cloth or pavement painted white "X's" prior to aerial photography of a region in Maine .  The photography is taken by an airplane at altitudes from 2500' to 12,000'.  These targets are used to orient the photographs takenb in order to match the photos to actual ground coordinates.  After the marks are placed, GPS equipment is placed above the point to configure the point in the Maine State Coordinate System.  Once the plane has flown the area, the temporary marks are then removed by the field crew. 

Attempts to contact the land owner are made prior to placing these targets.   Additionally, contact information (624-3493, Tim LeSiege, Supervising Engineer) is left by the target for the land owner with a date when the target is expected to be removed. 

 

How do I get authorization to obtain copies of aerial photos?

The MaineDOT Photogrammetry and Control Unit, provides such authorization.

 

This page last updated on 02/23/2006