Digital photogrammetry in the practice of open pit mining / Цифровая фотограмметрия в практике открытых горных работ

Mining activity monitoring, volume calculations, data for information systems of mining companies, decision making and planning, reclamation proposals are some of the most important fields, where photogrammetry can be used in open pit mining. Nowadays mostly digital methods find their utility in providing stereoscopic digitisation of a current situation of mining, precise orthophotos and digital terrain models. There are requirements for high precision especially in heights due to volume calculations and therefore high-resolution aerial images with low flight altitude are taken for the open pit mining purposes. The image scale is usually between 1:4,000 and 1:10,000. The huge amount of photos scanned with high geometric resolution and therefore gigabytes of data have to be processed fast and accurately. Fast computers and necessary photogrammetric software together with other ancillary programs (e.g. programs for digital terrain modelling (DTM), for computer aided design (CAD), and converters) are a basis of the work. However, above all this technical background the human factor is important. Well educated in photogrammetry, specialised in the field of open pit mining, experienced people with sufficient software knowledge are needed to achieve good results.
Despite images with high resolution, the biggest problems are caused by the image interpretation. The terrain of open pit mines usually does not show a variety of colours or shades of grey. Therefore shadows can be advantageous but also disadvantageous. A very good 3D visual perception without systematic errors is essential in stereoscopic digitisation. The setting of the smallest height difference at break lines and slopes is important for their digitisation in order not to lose time with too detailed designs, or on the other hand, to avoid a too benevolent work without the necessary details. If a final user of the data has not any photogrammetric equipment and uses a variety of software, different result formats are required in both vector and raster data. Specific demands have to be discussed very carefully and clearly defined. The paper illustrates also typical actual problems which can be met during the workflow. <...>