what is a"photogrammetric target"?

in reference to a post by bob salmon, a basic question what is a photogrammetric target?

Jack Boucher use 5x7 Linhofs and has developed a simple method of photogrammetri c targets that are placed on the building. He does this without using a reseau g rid in front of the film. They also are using the 45 Linhof Metrika photogrammet ric camera.

There are a few books available from Habs that outling Jack;s working procedures and equipment. I have also seen these sold by the photogrammetric associayion i n the

-- bob salomon (bob@hpmarketingcorp.com), March 09, 1999.

These are tools used by groups like HABS to indicate the precise size and scale of a building.

I use targets too. We do stereo close-range photogrammetric recording of buildings with Wilde cameras and 2X3 glass plates. The targets are placed on the elevation photographed so that negatives have scale in them from the start. Very easily seen targets are taped to the wall and photographed, and are measured in for precise distance. Later, since you know the distance apart, the photo can be scaled accurately. We've done the White House, Christ Church in Weems, VA, Merchant's Exchange in Phila. and many more this way. Good for standard photography for scale-rectified results too.