Ortho Imagery Picture

Keystone offers spatially rectified digital ortho-photos and ortho-mosaics to GIS professionals requiring base map images with a known spatial accuracy. High-resolution ortho-images (15cm GSD or better) can be produced to cover a specific project area, a complete city, or an entire region. For fastest turnaround and substantial cost savings, ortho-photos can be created from Keystone’s extensive library of digital imagery. Alternatively, Keystone can acquire new digital imagery that meets a client’s exact specifications.



Users with basic accuracy requirements will find Keystone’s standard ortho product highly suitable. Airborne GPS/IMU and optional ground-based GPS and CORS data are used to determine exterior orientations. Available digital elevation models covering the project area are inspected for accuracy and edited to minimize image warping due to unresolved features such as bridges and overpasses.

Combining the edited DEM with direct-georeferenced imagery, highly automated orthoproduction software creates RGB, Color IR, or 4-band ortho-photos in a variety of image formats and projections. Color-balanced ortho-mosaics, with automatically generated and manually edited seam lines, can optionally be created.

Accuracy measurements from a sample block of images orthorectified using this methodology are provided below:

Assessment Method 15cm GSD 30cm GSD
RMSE 0.68m 0.78m
NSSDA 1.15m 1.33m
RMSE @ 95% Confidence 0.67m +/- 0.083 0.78m +/- 0.066