The management of ski slopes requires a significant amount of geographical information. Every year, efforts for the re-opening of ski runs and the installation of snow cover systems require large-scale mapping from 1:5,000 to 1:500. The main ski slope services possess significant data assets, some of which can be shared for the good of all the players, including ski run services, ski lifts and tourist offices. Most of this information can be spatialized. Orodia, a technical consultancy in Grenoble, France, considered designing a shared tool, capable of archiving all of this information and making it possible to manage the slopes using maps.
Orodia’s GeoStation system, a geomatics solution dedicated to the management of ski slopes, is built on the GIS platform from GeoConcept SA, a company of Paris Cedex, France, that specializes in the creation and publication of PC-based GIS. The system integrates geographic terrain data with aerial photography, and ground and GPS surveys. Orodia also produces orthophotos when the ski slope requests them.
Ski slope managers are not interested in a complex tool that requires excessive investment time for training. With its advanced capabilities and power, GeoConcept responds perfectly to the specifications Orodia has defined, while at the same time providing attractive prospects for the user. A skier, for example, can use the solution in conjunction with his or her personal data assistant (PDA) and is able to obtain information while mobile.
Data CollectionThe tools Orodia uses for the constitution of the cartographic database amply cater to the ski slopes’ managers’ needs for geographical information. The most common process for putting together a geographic database has multiple steps.
The first step in setting up GeoStation is to determine with the operator the zones he or she wishes to lay out, develop or manage. Then potential players likely to be interested in the use of the data are sought out. In some ski resorts, the users are numerous (including water and forestry departments, development planning departments, natural hazards research departments, tourist information offices and sports offices), and their operating systems are often different.
Orodia was easily able to provide all of the data collected by using the various exports available with GeoConcept, such as software from MapInfo (MapInfo Corporation, Troy, N.Y.), AutoCAD (Autodesk Inc., San Rafael, Calif.), and ArcInfo and ArcView (ESRI, Redlands, Calif.). GeoConcept data can be exported into Excel, Scan25 or Geo_tiff.
The data provided in dynamic 3D illustrations were subsequently produced for the tourist information offices. The main data collection technique is photogrammetry, carried out with an analytical DSR 14 plotter (Leica Geosystems, Norcross, Ga.) or a digital workstation to process the calibrated aerial images. Of course, the accuracy of the data obtained will depend on the scale and the quality of the photos. For this, Orodia consults aerial photography companies with extensive knowledge of mountainous environments and all the risks involved.* The flight plans are often very tricky to determine because the terrain relief associated with the slopes can require more end lap (photographic overlap in the direction of flight) and side lap (photographic overlap in the direction of cross flight) to ensure adequate coverage in the photography. (*Fabrice Collinse often recommends one flight at 1:15,000 for a general cartographic study, coupled with a flight at 1:4,000 for sectors requiring a higher density or accuracy, in particular on the lower ski slopes and the ski lift departure and arrival areas.)
Data ProcessingIt is also possible to obtain digital orthophotos from the aerial photos taken during these flights by scanning, rectifying and mosaicking them. This provides excellent additional information for the GIS, allowing users and decision makers a better view of the site.
The control points used for the setting of the aerial photos in the national reference system are most often produced using a differential GPS, the Leica GPS System 500, which offers remarkable performances when faced with the relief for which accessibility and visibility are often uncertain at high altitudes. All of the elements visible in the ski slopes, such as buildings, ski lifts, pylons, ski run earthworks, vegetation and altimetry are captured in 3D in MicroStation (Bentley Systems Incorporated, Exton, Pa.) and structured to be easily integrated into GeoStation. The altimetry, collected as contour lines or random point DTMs and rupture lines, enables the subsequent creation of an altimetric meshing with uniform spacing, making 3D-type applications possible, such as longitudinal and cross profiles, curbature, surface water flow, etc. The elements are customized according to the client’s needs and enhanced by attribute information in order to retrace the history of the infrastructures and manage their maintenance.
The photogrammetric control points also serve as a reference grid for all of the sectors requiring large-scale surveys. The standard CAD and digitization procedures under AutoCAD or MicroStation enable the finalization of the basic cartographic background and its integration into the GIS data model.
Other types of more complex information may be added upon request, such as natural hazards, aspect and exposure, catchment areas, etc. The cartographic base created in this way makes the management of a ski slope possible from scales of 1:25,000 to 1:500.
Risk Prevention and ManagementThe relevance of the GIS is appreciated immediately after its installation, as the stakes are extremely high. All of the avalanche flows are spatially archived in order to anticipate risk-prone areas and sectors where Gazex (gas triggered) and Catex (cable transported trigger by explosive) avalanche triggers will be positioned. The security of the ski runs is also directly affected. By spatializing all of the accident sites, it aids in determining the sectors to improve during the next earthworks projects. GeoStation quickly provides site managers with the positions of underground networks with, if need be, a buffer zone determined using GeoConcept’s standard topological tools. In terms of altimetry, the processing of vector DTMs is limited. GeoConcept enables the transformation of meshing into raster DTMs in order to combine raster/vector analyses.
The management of snow cover is also part of GeoStation’s applications. In La Plagne, (Haute Savoie), GeoConcept’s Image module permits developers to establish maps of slope and aspect in order to assist the engineering departments in determining favored zones, and with the installation of artificial snow networks.
Closer to the ground, ground surveys may be added on the photogrammetric base level using differential GPS or theodolite surveys. For example, the edges of the ski slopes are surveyed in winter on skis. The surfaces obtained from GeoConcept have quickly convinced operators of its benefits since they can accurately determine for themselves the cost of re-vegetation or snow grooming.
The water, communications and electrical networks are added according to the means available: GPS or theodolite. Here also, the significance is immediately manifested, as each year forgotten underground networks resurface when using power shovels, and the rupture of certain conduits can cause much damage. The knowledge of the location, dimensions and power of certain lines makes it possible to limit these risks.
According to the customer’s project, Orodia configures the attribute database to enable the management of all or part of the ski slope simply using maps. The GIS therefore equally becomes a project simulation tool because of its real-time 3D module, a CAMP (Computer-Aided Management of Production) tool, a means of communication regarding ski run conditions and security reasons with tourists and acts as a tool to optimize snow grooming plans. Thanks to these GIS and the use of GPS, piste bashers, the nighttime operators who clear the ski runs, and other isolated workers increase their security.