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AT Scans

Aerial Triangulation (AT) Scans are "soft copy" digital images of black & white and colour aerial photography in BC that include aerotriangulation data. AT scans are used for control and mapping projects. AT control information is available for 3/4 of the province of British Columbia.

Product Details

Soft Copy Aerial Triangulation Example Thumbnail

Soft Copy Aerial Triangulation Example Thumbnail

The AT scan would be bcb01009_001_14n_at.tif.

Scans are created by scanning 10" film negatives on specialized scanning equipment. Colour negatives are scanned at a resolution of 21 microns (file size: 400 MB) and black and white negatives are scanned at a resolution of 14 microns (file size: 300 MB).

Files have 8 bit pixel values and are untiled, undodged and uncompressed TIFF 6x format.

Frequently Asked Questions

What is "control"?

Control is horizontal, vertical and pass points triangulated and either referenced on digital scans or drilled into hard copy air photo diapositives.

What is cross-pugging?

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


Scans can be viewed with most viewing software, although they are intended for mapping applications such as DIAP viewer.

Product Resources

AT Control Models

If AT control models are required in addition to the scans, they can be ordered by including the following information:

  • Roll and frame numbers
  • 1:20 000 map sheet number

How to Acquire

Search using Base Map Online Store Discovery Tool Open in Google Earth


Note: At this time control models cannot be purchased online.

TIFF scan of black/white or colour air photo with TRIM AT (pixel) control points embedded $18.50 each

Search and order using the Base Map Online Store

Before using the Base Map Online Store:

Please review the following introductory materials before proceeding to the BMOS site: