GeoIdee; GIS, Database and Software Engineering
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Locally optimized transformation parameters for Pulkovo-1942 datum
The Soviet topographical maps are a highly detailed source of information for many fields of research, engineering and natural resource management. In combination with accurate satellite imagery and GPS measurement highly valuable baseline information can be derived.
The topographical maps are based on the geodetic datum of Pulkovo-1942 and the ellipsoid of Krassowski-1940. For several reasons an adequate transformation parameter set between the WGS-1984 and the Pulkovo-1942 is not available for Tajikistan. The EPSG database v7.11 provides about 21 different versions of parameter sets. But unfortunately, none of them is accurate enough to combine the Soviet topographical maps in Tajikistan with satellite imagery and GPS measurements based on the WGS-1984 datum. Additionally, local distortions of the base coordinate frame caused by the triangulation methods adds errors to the consistency between the different data sources.
One possible solution to overcome these shortcomings is the calculation of locally optimized transformation parameters between the WGS-1984 and the Pulkovo-1942 datum. For several regions of Tajikistan, such optimized parameters were calculated based on the equation of the Standard Molodensky Transformation.
 | The Standard Molodensky Transformation is based on a shift of the coordinates along the 3 axis with the values dx, dy and dz. As input for the calculations to retrieve the three Molodensky parameters, several identical points were measured in ellipsoidal coordinates of the WGS-1984 and Krassowski-1940 ellipsoids. The three parameters were derived by using least squares adjustments. Depending on the quality of the input data, the 7-Parameters of the Coordinate Frame Rotation or Position Vector Transformation methods could also be provided. |
The following vector field shows the improvement between the standard geocentric translation applied in Tajikistan (left) and the locally optimized Molodensky parameter set (right). The control points were measured in high resolution orthorectified satellite imagery (WGS-1984) and topographical maps 1:50'000 (Pulkovo-1942).
| Existing Geocentric Translation EPSG 1254 | Locally optimized Molodensky parameter |
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The systematic shift of the coordinates caused by the EPSG 1254 transformation was fully removed. The average residuals of the control points were reduced from 53m to 16m. The fitting accuracy of the satellite imagery and GPS measurement was significantly increased.
In another region the vector field of the residuals is showing similar effects. The systematic shift of the coordinates in Western direction was largely removed and the average residual error was reduced from 85m to 21m. The significant difference of the vector directions between the first and the second example may result from local distortion of the base coordinate frame.
| Existing Geocentric Translation EPSG 1254 | Locally optimized Molodensky parameter |
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The method applied can be used in project regions where Soviet topographical maps and satellite imagery with GPS-based field observations shall be combined. It also can be used for the transformation of digitized data layers which are based on the Pulkovo-1942 datum into WGS-1984-based reference systems such as the new coordinate frame of Tajikistan.
 | The calculated transformation parameters can be applied in all standard GIS software packages such as ArcGIS, Quantum GIS or gvSIG. For ArcGIS users the transformation set can be stored as Custom Geographic Transformation file (*.gtf file) which can be distributed among the users of an organization. The *.gtf file can be directly used within the user interface of ArcMap and will be applied to all data sets in the data frame. |
The use of topographical maps at a scale of 1:25'000 or above could improve the quality of the calculation of the parameter sets considerably. GeoIdee.ch offers the calculation of optimized parameters as service, please feel free to contact.
Mapping workshop for Deutsche Welthungerhilfe e.V. in Southern Tajikistan
Within the project for thematic map production for the Deutsche Welthungerhilfe e.V. (WHH) a workshop was conducted by GeoIdee.ch in the WHH field office in Baljovan. Main target of the workshop was the detailed definition of the map series to create. The projects of WHH in cooperation with CESVI are addressing the development of a sustainable and holistic watershed management approach.
Accompanying the detailed management plans two map series have to be elaborated:
- Watershed Management Map
- Pasture Management Map
The Watershed Management Maps are providing general information about the current or planned land-use and activities to achieve. The Pasture Management Maps are addressing the usage and rotation of the areas used for pasture during the three main seasons Spring, Summer and Autumn.
During the workshop the following topics were addressed:
- Main purpose and core message
- Audience to be addressed
- Detailed content of the maps and background to be used (topographical map vs. satellite imagery)
- Additional information such as guidelines or best practices to be added
As base-information hand-drawn land-use maps of the individual watersheds are used. These maps were elaborated by staff of WHH in cooperation with the villages. For the different management plans and maps a participatory process in the villages will be conducted.
| Land-use map | Proof-of-concept |
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| Base-line mapping of the current land-use of the individual watersheds elaborated within workshops in the villages. | Proof-of-concept and color testing of pasture management information using analog printouts and crayons. |
The findings of the workshop are resulting in a detailed concept for the individual map series. Based on the information mapped by the staff of WHH and CESVI and the map concept the production of the thematic map will be done during Mai and June 2012.
Standardized map layouts for thematic maps
Using the capability of DataDrivenPages of ArcGIS 10 opens additional possibilities to create easy map series over large areas. For this reason the usage of the MapBook extension of ESRI, which source code had to be adapted by geoidee.ch to produce map series with overview maps and complex layouts, was migrated to DataDrivenPages.
The usage of DataDrivenPages in combination with the raster date catalog of the pixel maps of Tajikistan and the index layer of the topographical maps with the individual sheet names allows the setup of highly dynamic map layout.
As base a standardized layout can be used in which the main content such as map view, sheet name, names of the adjoining sheets, coordinate system … is dynamically set. The standardized layout provides a large freedom to add individual information about the thematic data displayed.
The above example showing the standardized map layout populated with thematic information with extensive explanations at the left side.
Some examples of map series with different thematic content and field of usage:
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| Topographical based map for planning and general purpose. | Information about soil degeneration and successful soil conservation. | Back-country skiing routes and information about avalanche release zones. |
Using a standardized map layout provides a quick and cost effective way to publish any kind of geographical data in combination with a topographical (or satellite based imagery) background information. The maps can be retrieved as hardcopy in a format of 40.5 cm by 57.0 cm (unfolded) or 9.5 cm by 13.5 cm (folded).
GIS certificate for second round of TSDWP internship students
During the Navruz celebration of the Tajikistan Technical University in Dushanbe, the eight internship students from the Tajikistan Safe Drinking Water Project (TSDWP) of USAid received their GIS training certificate handed over by GeoIdee.ch Director Yvo Weidmann.
The students are enrolled in master courses in civil engineering and water engineering at the Construction and Architecture Faculty of the University.
At the TSDWP the students got intensive training in the usage of the WaterCAD system and a basic introduction into GIS and spatial data handling. The GIS training was following a typical workflow of building up a tailor-made GIS, here for the usage in the field of drinking water infrastructure. During the training provided by GeoIdee.ch following topics were covered:
- General understanding of maps and spatial relations
- Concept of map projections and coordinate transformation
- Vector-based data modeling
- Vector data versus raster data; discrete data versus continues data
- Analysis of spatial relationships
- Setting up own data sets based on specific needs and interests
- Data capturing with field work
- Cartographical representation of the different data types
New data storage for pixel maps of Tajikistan
The storage system of the pixel maps of Tajikistan (scales of 1:50'000, 1:100'000, 1:200'000 and 1:500'000) was migrated from simple data catalogs over to mosaic datasets. The new data storage system allows a simpler and more user friendly usage of the several gigabytes of data.
The individual mosaics are containing following amount of individual map sheets:
- 9 sheets 1:500'000
- 47 sheets 1:200'000
- 147 sheets 1:100'000
- 453 sheets 1:50'000
All individual sheets are geo-referenced and clipped to their extends which builds the preliminary conditions for a seamless map cover.
Specially the usage of the mosaic allows a new way of distribution of the pixel maps. Instead of single sheets, a seamless mosaic of any area of interest (AOI) can be exported. The following example shows an export of an AOI which stretches over 4 single map sheets. Such kind of exports can be interesting for individual watersheds, roads or river sections.
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The exported subsets are available as color or grey-scale geo-referenced tiff files. Interested parties can submit their AOI as GoogleEarth KML-file or ESRI shape-files. The export will be based on the submitted geometries. The price calculation of the processing costs (preprocessing, data handling and export) will be based on the total amount of square kilometers. Please feel free to contactgeoidee.ch directly if any interest.
Contact
Yvo Weidmann
Farkhod Street 4
TJ-734003 Dushanbe
Republic of Tajikistan
Mobile +992 985 311 090
Mail yweidmann (at) yahoo (dot) com
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