The GSD calculator covers all the mayor large format aerial survey camera systems, medium format aerial cameras, but also some SLR systems widely used in an UAV environment.
Basically if helps to compare aerial cameras on a practical approach, based on their geometry, pixel arrangements /CCD and calculates overlap, sidelap, GSD and other relevant information.
It also provide a comparision function of scanned film negatives, based on photo scale to modern recording systems based on Ground Sampling Distance.
A small calculation section is provided to perform a quick proposal based on the used camera and some relevant flight plan parameters, such as GSD, overlap, distances and flight line layout.
Cameras using interchangeable lenses can be used as well.
If you use different lenses, you may input your focal lenght in the cal. focal lenght field.
In case you use the designated lens often, you may click on “Lock this Camera” and the calulator will remember this particular type of aerial camera.
Ground Speed and Camera Cycle
the calculator helps by monitoring the camera cycle. Because of the variety of cameras and storage systems, it provides a warning message if the cycle time would become lower as 3 seconds. please refer to your camera manual for max. cylce time and check your Ground Speed / Altitude settings.
Leaning and Occlusion
can be calulated as well, you may input street width and get results.
Full Resolution (Mapping Grade) vs Bayer (Half Resolution)
All mayor large format cameras of Vexcel and Z/I using the pan-sharpening method, most push-broom sensors as well (Leica).
Bayer pattern interpolation
Unfortunately the pixel itself is colorblind. It can record only the total intensity of the light on its surface.
In order to get a full color image, sensors using color filtering or pan-sharpening methods. Once the camera records all 3 colors, it combines them to a full colored RGB image. (Infrared would be the fourth color/band, if applicable).
There are several methods, e.g. Beam Splitters, rotating filter slides (still cameras) or as the most economical way, the Bayer pattern color filter array. Basically there is a filter element placed on top of each pixel, which collects red, green or blue intensity information. Then, a special intelligent interpolation algorithm collects information of each pixel and its neighborhood location. So the final pixel “color” will be an interpolated color of the information collected around each pixel or the True Color of the pixel is obtained by averaging the color of the surrounding pixel. The typical Bayer pattern is made by 2 rows of pixel.
1st row: red – green – red pixel
2nd row: green – blue – green pixel
Finally one will get double amount of green pixel comparing to red+green (50% green, 25% red, 25% blue pixel or in other words: 66% of the resulting image is interpolated, not recorded).
Mr. Bryce Bayer (Kodak) introduced this system 1976 in order to keep track with the sensitive range of the human eye.
The advantage of this pattern is that a camera needs only 1 sensor, as we see in most commercial camera, even in smartphones. So cameras became small in size and cheap in price and the necessary demosaicing Algorithm is just a simple piece of software. The disadvantage is the reduced resolution of the sensor by 50%.
An aerial camera using pan-sharpening method provides a full resolution image, formed by the panchromatic CCDs. The color information comes from separate red, green, blue (infrared) sensors and lenses.
Typically the actual resolution of a Bayer pattern CCD is 0,58 * Megapixel.
What is new?
Version 4.30 (February 2015)
- more IGI DigiCam introduced
- PhaseOne new models introduced
- Visual Intelligence iOne IM+ (quadro) introduced
- Vexcel Ultracam Hawk
- Vexcel Ultracam Falcon now in 136 and 195 Megapixel version
- Canon EOS 5 Ds (50 Megapixel) SLR intorduced (preliminary sensor)
- software update improved