2D Models Development TechnologyDevelopment stages
Exact area of interest (AOI) delimitation
Model frame can be provided by customer as well as they can be created by our experts with compulsory client’s approval.
Images selection for each AOI.
We use high accuracy satellite images and stereo pairs with resolution 2.5-24m. Type of image is selected in accordance with 2D models accuracy requirements, suitable for customer. Always the most recent images are selected.
If in supplier’s archive the recent images are unavailable, we order direct shooting of AOI. Expected new images delivery time is from 2 week to 3 months, depending on weather conditions.
Types of satellite images being used in models preparation process
- IRS LISS3 – resolution 24m
- Aster, Landsat 7 – resolution 15m
- SPOT 2-4, ALLOS – resolution 10m
- IRS P6 – resolution 5-6m
- SPOT 5 – resolution 2.5m
- Cartosat 1 – resolution 2.5m
- EROS-A – resolution 2m
Data generation process.
Digital Terrain Model creation technology
DTM describes all the features of earth surface, position and outlines of nature objects, which are preventing signals propagation.
DTM can be prepared using two different methods:
- basing on SRTM/ASTER DEM data – is used for regional models creation
- Digitization of terrain contour lines from topographic maps with respective scale (depending on maps availability) – is used both for regional and city models
Vertical accuracy (Z) in DTM depending on usage of different initial data.
|Maps 1:500 000||Maps 1:200 000||SRTM||Maps 1:100 000||Maps 1:50 000||Maps 1:10 000, 1:25 000|
Shuttle radar topographic mission (SRTM) – Radar topographic imagery of most of the Earth’s territory, excluding the northern (>60) and the southern (>54) latitudes and oceans, realized during 11 days of February 2000 by special space radar system. More than 12 terabytes of data were collected by two radar sensors SIR-C and X-SAR. Final version was additionally corrected. The correction included: data errors filtration, coastlines and water objects highlighting.
Result data corresponds to Interferometric Terrain Height Data (ITHD)-2 (dimensions of element 30x30m; vertical accuracy ≥16m).
ASTER – Advanced Spaceborne Thermal Emission and Reflection Radiometer. Equipment is mounted aboard Terra satellite, which was launched in December 1999 and consists of two stereoscopic telescopes which are shooting in nadir and back in lower infrared range. For Aster GDEM creation the automated data processing of all data archive (consisting of 1.5 mln scenes) – were used. ASTER GDEM includes earth surface between 83° NL and 83° SL and consists of 22,600 pieces 1°х1°. Vertical accuracy – 20m, horizontal accuracy – 30m.
Clutter model producing technologies
Clutter model describes all the terrain and build-up area features, which are resulting on signal propagation. Such models of earth surface are being unified in different classes: classes of buildings, classes of water objects, classes of landscape objects and vegetation.
Main sources of data for clutter model creation are satellite images with resolution 2,5 – 24m, depending on model type – Regional or City. For each type of model the most recent images are being taken for the maximum data accuracy.
Types of images used for clutter models creation.
|Model||Type of image|
|Regional||Landsat 7, Aster, IRS LISS 3, SPOT 2-4, Allos, IRS 1C/1D, P6|
|City||IRS 1C/1D, P6, SPOT 5, EROS-A, Cartosat 1, Allos|
Clutter model is produced by photo interpretation of orthorectified satellite images.
Process is maintained in manual mode to gain the most precious correspondence of initial image and classification result.
Manual processing technology provides considerable better result (in comparison with automated) because it allows to classify clutters within many parameters, which are important for wireless networks planning, such as build-up density, its specific features and widths of the streets.