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In today's world, GIS gives you the power to relate and integrate various other systems and provide you with robust decision making systems. Professionals who depend on a GIS system to make important business decisions need a full-service, experienced source to help manage this sophisticated and indispensable tool. That is exactly where we come in with our start-to-end full-service life cycle project support on your GIS projects through requirements analysis, data conversion, base map creation, database designing, data modeling & analysis, and customized application development.

« Point Cloud Processing
« Spatial Data Management
« Geospatial Application Development
« Modeling & Analysis-2D, 3D
« Legacy Data Conversion
Photogrammetric Analysis
« Orthophoto Rectification
« Image Classification & Analysis
Aero Triangulation & Block Adjustment

Analytical Aerial TriangulationAnalytical Aerial Triangulation is an essential part of a successful project and in essence the heart of a photogrammetry project.

To optimize schedule and minimize labor associated with extensive ground surveys, Stesalit offers complete in-house conventional and softcopy fully analytical aerial triangulation (FAAT) services, providing highly accurate control for map production. This process can further be enhanced when Airborne GPS supported data are available.

Project Preparation

Once aerial photos have been obtained, all point selection, layouts and codings are determined by Stesalit?s experienced personnel according to industry standards.

Softcopy analytical aero triangulation is accomplished using software. Utilizing high resolution scanned images, this system minimizes film handling while matching ground points at variable pixel size. Interior orientation, control and pass point selection, and refined plate coordinate generation is accomplished in an automatic or semi-automatic process. Pass points are selected within the AT software using auto-correlation within the image overlap areas. Increased numbers of pass points strengthen the model setup and reduce parallax.

Materials required for AT

Mosaic, line map or schematic of the project area showing flight lines, project boundaries, control point locations and identification numbers Contact prints of all exposures to be triangulated with the control points clearly identified Ground control coordinates and estimates of horizontal and vertical accuracy preferably on a floppy disk or via Email Most recent calibration certificate for the taking camera Film diapositives of all exposures to be triangulated


Using the basic horizontal and vertical control survey data, AT team establishes 6 horizontal and vertical points per model by means of analytical aerial triangulation. The FAAT adjustments are performed using software, and the data is measured on our Softcopy Stations or on first order Analytical Stereo Plotters.

Expected Quality and Accuracy

The accuracy of the analytical triangulation will be less than 1 part in 10,000th of the flight altitude and is determined by the root mean square (RMSE) of the AT ground control residuals.

Accuracy of the analytical aerial triangulation can also be verified by the inclusion of checkpoints with the values withheld in the adjustment and later verified in the final results.

A sealed and signed copy of the aerial triangulation is delivered with each project.
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