High Detail Remote Sensing
A common way to rehabilitate open cast mining operations on sloping ground where significant erosion might take place, is to create a patchwork of heaps which are then grassed using plugs or patches. For contract management purposes it is necessary to assess the survivorship of these plantings when they are three or four weeks old. Due to the rough nature of the site it is impossible to do this using conventional quadrat counting techniques. Photographic counts are preferable but the grass plug targets are very small and the difference between living and dead can be subtle.
Two photogrammetric systems were developed and tested on a specailly created control area.
One is a ground based system using a camera and distance meter suspended on a survey staff. This is the simpler and cheaper of the two but it can only be carried out on a sampling basis. 100% coverage of the site is not possible.
The other sysytem involved the deployment of ulta low level aerial infra red photography. Using this system a complete count and analysis of every planted plug can be achieved across the entire site. It was found that plantings could be identified with a 95% level of confidence semi automatically and then those plantings could be further categorised as living or dead with an 80% level of confidence via a fully automatic process.