Aerial imagery must adhere to the following specifications:
- Images must be collected as Red, Green, and Blue (RGB) images offering a natural colour rendition. This means the colour of an object in the image is the same colour as if you viewed the object in person e.g., a green tree appears green.
- Images must have a radiometric resolution of 24-bit (3 x 8 bits per band).
- Images must be delivered in JPEG format.
- Images must be well balanced, well illuminated, and sharp.
- Images must have an average Ground Sample Distance (GSD) of 5cm or better. Ground sample distance (GSD), also referred to as pixel size for an image, is the distance on the ground, measured in x and y components, represented by each pixel in the image.
- Images must be acquired on clear, cloudless days at a time which minimizes shadows.
- Images must be 100% cloud free.
- Only fixed focal lenses may be used. Wide angle lenses (with minimum focal length of 55% of sensor diagonal or 67% of sensor width) may be used.
- The camera date and time must be set to the nearest second on the local time system.
- The camera must have a pixel pitch of at least 4 microns, preferably 6 microns.
- Camera image stabilization is strictly forbidden as image stabilization affects the geometry of the camera.
- Images must have a minimum forward overlap of 80% and a minimum lateral (side) overlap of 70% for urban areas, this can be reduced to a minimum of 60%/30% for flat areas.
- Images must be geo-referenced. Quality tagged high accuracy image exposure coordinates on WGS84 (local official datum optional) and derived from carrier phase GNSS PPK interpolation of exposure events is preferred.
- Images must be properly identified by file name.