Fast orthophotos for limited budgets...

Digital aerial image capture, combined with airborne GPS and IMU (Inertial Motion Unit) technology, enables the generation of a new type of product, the 'fast-look' georeferenced image. This product is essentially an upgrade of the conventional contact print. Being a digital product from the start means that we can georeference the product quickly and provide it in a form that can be ingested into a GIS within a matter of a few days or weeks rather than months.

 

The image is spatially georeferenced by capturing airborne GPS data for the photo-centre during the survey. Its orientation is known thanks to the IMU technology, which records the image tips and tilts in flight. In combination with an automatically generated DTM the images can be orthorectified to a spatial accuracy of better than 2m. Colour balancing of the images is performed to provide an almost seamless ortho coverage enabling the fast-look georeferenced images to be a very useful low-cost information source for natural resource assessment and like applications.

 

What are its limitations? The concept is of fully automated processing and therefore it is not possible to generate the quality product of a full ortho mosaic product. The high quality ortho mosaic product will be spatially more accurate due to ground control, triangulation and a stereo edited DTM. The high quality ortho product will also be radiometrically seamless. The Fast Look Image product will have small geometric errors and slight radiometric differences from one ortho to the next

 

For many clients, the Fast Look imagery is a way of covering a large amount of territory with high resolution imagery at an acceptable spatial accuracy and at a budget cost.