Block Aerotriangulation (BAT, AT)

process of adding "ground control" points and computing coordinates and angles for camera position

Each pair of photographs used for 3D compilation must have at least three "ground controls" (premarked targets surveyed in user defined coordinate system) within area of overlap between centers of each photograph. Block aerotriangulation procedures minimize need for these premarked targets. Known X Y Z position and corresponding angles of rotation of a camera for each exposure provide sufficient information for georeferencing images in orthophoto production.

Since results from block aerotriangulation represent the basis for any further mapping and ortho production, it is considered one of the most critical preparation tasks.

Starting with carefull selection of the area for a new point, it is first marked on a contact print

and then precisely transferred onto the diapositive.

Emulsion of the diapositive is 'scratched' to form a perfect circle, typically 60 microns in diameter.

Once all points are marked and transferred, each

stereopair is measured on our First Order Analytical plotter

Collected data is processed with BINEM, simultaneous block aerotriangulation adjustment program, resulting in final coordinate values for each measured point, as well as spatial position of each projection center.

Results, residuals and final adjusted coordinates, are presented in a tabular form, as an ASCII file.

Point Co. developed in-house program for graphic presentation of models layout to aid AT analysis and further project management

Another additional product is model SETUP parameters for analog instruments. Presently, Santoni IIc/G6 and Wild B8 models are supported.

| SANTONI IIC/G6 and Wild B8 Setups (w=w-100) |
| Common PHI Santoni: red=positive values, white=negative values |
| POINT Photogrammetric Services, FAIR OAKS, CA (916) 536-0487 |
Emulsion against the carrier glass, order of exposures as declared below

model: 101-102 (left-right)
LEFT k= 94.85 f= 100.40 w= 199.53 Santoni Common PHI= 1.81 RED
RIGHT k= 96.65 f= 100.43 w= 200.32 Wild B8 Common PHI= 99.89

model: 102-103 (left-right)
LEFT k= 99.83 f= 100.22 w= 200.30 Santoni Common PHI= 2.06 WHITE
RIGHT k= 97.85 f= 100.40 w= 200.47 Wild B8 Common PHI= 100.13

model: 103-104 (left-right)
LEFT k= 97.56 f= 100.23 w= 200.51 Santoni Common PHI= 5.04 WHITE
RIGHT k= 97.30 f= 100.47 w= 200.50 Wild B8 Common PHI= 100.32