Aerial Triangulation

Triangulation is a technique for establishing the relative position of two or more points. Aerial triangulation (AT) is a method for producing maps by overlapping aerial images.

How it Works

Aerial triangulation represents the process for determining the correct position and orientation of each image in a series of aerial images so they can be compiled into a map.

Triangulated horizontal, vertical and pass points are referred to as the control. Control may be referenced on digital scans, or drilled into hard copy photo slides and transparencies. AT control information is available for three quarters of the Province of B.C.

Cross-pugging is triangulated data that is transferred from older, existing air photos to newer photos and scanned images to control new mapping.

Product Details

Aerial triangulation scans are digital aerial photos of British Columbia that include aerotriangulation data. AT scans are used for control and mapping projects.

Scans are created by scanning 10" film negatives on specialized scanning equipment. Colour negatives are scanned at a resolution of 21 microns, and black & white negatives are scanned at a resolution of 14 microns. Files have 8-bit pixel values and are untiled, undodged and uncompressed TIFF 6x format.


This manual is intended to be used for aerial triangulation with or without differential GPS on board the aircraft to provide densified control points for large, medium and small scale digital and analogue mapping produced for B.C. provincial government and any other mapping projects in British Columbia.

How to Acquire

Aerial triangulation scans can be ordered from the Base Map Online Store or opened in Google Earth:




TIFF scan of air photo with embedded TRIM AT (pixel) control points

$18.50 each

AT Example

Soft copy aerial triangulation example

This aerial triangulation scan's filename would be "bcb01009_001_14n_at.tif"

Base Map Online Store

It is recommended that users understand the Base Map Online Store instructions and policies before making an order.


Aerial triangulation scans of B.C. are produced by GeoBC.

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