Working with Projections and Datum Transformations in ArcGIS

Transcription

1 Werner Flacke / Birgit Kraus Working with Projections and Datum Transformations in ArcGIS Theory and Practical Examples First impression 2005 Points Verlag Norden*Halmstad

2 VII Table of Contents Introduction 1 Introduction to coordinate systems The significance of coordinate systems Measurement units Basic terminology of coordinate systems Coordinate system data models Standards: EPSG/POSC/ISO 19111/OGC/WKT Coordinate system syntax in ArcGIS Desktop 14 Working with ArcGIS Desktop - first steps The Desktop Help System in ArcGIS A quick start for the practically minded Loading data Adding graticules Setting the display units for the coordinates Changing / setting the output CRS Addendum to the measurement experiment Area and length attributes Projecting with ArcMap New warning in ArcGIS 8.3 when editing Coordinate systems in ArcCatalog Associating coordinate systems with datasets X/Y, Z and M Domains Coordinate systems in a geodatabase and in ArcSDE Coordinate systems of raster data in ArcSDE Coordinate systems of shapefiles Coordinate systems of raster data Coordinate systems and image catalogs Coordinate systems and Grids Coordinate systems and TINs Coordinate systems and CAD data Coordinate systems and SDC files Coordinate systems and X/Y coordinate tables Georeferencing raster data 50 Basic geodesy Introduction Reference systems Global reference systems ITRS (International Terrestrial Reference System) ETRS89 (European Terrestrial Reference System) WGS84 (World Geodetic System 1984) NAD 1983 (North American Datum 1983) 65

3 VIII Table of Contents Conventional reference systems ED50 (European Datum 1950) DHDN/Germany Pulkovo Datum 1942 / former Soviet Union and neighboring countries NAD 1927/NorthAmerica OSGB36 (Ordnance Survey Great Britain 1936) Describing the shape of the Earth Sphere, ellipsoid, geoid Reference ellipsoids The geodetic datum Dimensions of various ellipsoidal models The vertical datum Transformation, Conversion, Projection Transformation methods Parameter based transformation methods 73 Three parameter transformations 73 Seven parameter transformations 73 Bursa-Wolf 74 Molodensky-Badekas Grid based methods NTv NADCONandHARN Further predefined geographic transformation methods Relationships between selected reference systems Projections Projection surfaces Conical projections Azimuthal proj ections Cylindrical projections Projection properties Geodetic coordinates Gauss-Kruger coordinates (transverse Mercator projection) UTM coordinates (transverse Mercator projection) Lambert conformal conic coordinates 90 5 Working with ArcGIS Desktop - main section The organization of coordinate systems in ArcGIS Desktop The predefined coordinate systems Predefined datum transformations in ArcGIS Grid based transformation methods in ArcGIS Assigning coordinate systems Assigning coordinate systems in ArcCatalog Assigning coordinate systems with Arc Toolbox 105

4 IX Assigning coordinate systems in ArcMap Assigning coordinate systems in batch using scripting Projections and transformations with ArcMap Projections The GCS warning in ArcMap Datum transformations in ArcMap DHDNtoETRF_ Projection and two step transformation between ED50, ETRS89 and DHDN in ArcMap Adding XY-data Adding GPS data (WGS84) from text files and transforming to the DHDN Projection and transformation of raster data in ArcMap ArcIMS layer in ArcMap WMS layer in ArcMap Projections and transformations with ArcToolbox Projection with ArcToolbox Changing zones in ArcToolbox Single step and composite transformations Single step transformation Composite transformation Grid based transformations Projecting raster data with ArcToolbox Spatial analysis in ArcMap Spatial selection and datum transformation The Buffer Wizard in ArcMap The extensions Spatial Analyst and 3D-Analyst Coordinate systems and geodatabases Geoprocessing and scripting with coordinate systems Overview Geoprocessing and ArcToolbox Modeling and scripting ProjectRaster script (with transformation) Find PRJ file script ProjectASCII script Official and commonly used coordinate systems The geographic reference systems Unified European reference systems Geographic transformations NTv2 in Canada NTv2 in Australia NTv2 in New Zealand NTv2 in France NTv2 in Germany

5 6.2.6 NADCONandHARNintheUSA Grid based transformation in the UK Polynomial transformations Projected coordinate systems UTM Gauss-Kriiger and other Transverse Mercator projections Lambert conformal conic Projections Special projections State Plane coordinate systems in the USA Other coordinate systems in the USA 186 Practical work with ArcGIS - special cases Customized coordinate systems Creating and modifying coordinate systems GPS data (WGSJ 984) on a map from Rwanda (Arcl 960) Customized, persistent transformations User defined transformation Customized transformations Maps in borderline regions The conjunction of Germany, Austria and Switzerland Grid systems in layouts The UTM grid reference system Projected grids Special cases Datum transformation in Sweden NAD 1927 to NAD NTv2 in Canada Changes in ArcGIS Troubleshooting hints and prjfinder 219 Frequently Asked Questions - FAQ 231 Why are the points 50 m m away from where they are supposed to be? 231 How precise are projections and datum transformations? 231 Are there differences between on the fly projection and other methods? 232 How can I store custom CRS? 232 Which datum transformations are predefined? 233 How can I create a custom datum? 233 Custom datums in Arclnfo Workstation 233 Custom datums in ArcGIS Desktop 233 Is it possible to extend the list of predefined datum transformations? 234 Can I add transformation parameters to a PRJ file? 235 What is the significance of the transformation direction? 235 Why are the signs of the rotation parameters sometimes reversed? 235 Do I always have to set datum transformations manually? 236 ETRF = ETRS? 236 What does GCSAssumedGeographicl mean? 237

6 XI Can I influence AssumedGeographicJ / NAD1927? 237 How can I convert the 42/Pulkovo system to Gauss-Kruger/DHDN? 237 Are there differences between ArcToolbox and ArcMap? 238 How can I transform between different meridians or from one kind of angular unit to another? 238 How can I project or transform Tele Atlas data? 238 What do I need to be aware of regarding coverages? 239 The Define Projection Wizard for coverages, Grids or TINs What should I bear in mind with TINs? 246 What should I bear in mind with Grids? 248 What should I bear in mind with DWG/DXF/DGN data? 250 What should I bear in mind with the GPS extension? 250 Can I store transformations in an MXT file? 250 Can I change or delete transformations in ArcMap? 250 What is the significance of the warning about different GCS in ArcMap? 251 How can I cause the datum warning to be issued again after I have permanently dismissed it? 252 What should I bear in mind with ArcPad shapefiles? 253 How can I project and transform raster data? 253 Can I deactivate on the fly projection? 253 How can I determine the CRS of a dataset? 254 In which coordinate system should a centralized data pool be stored? 254 What should I bear in mind with ArcIMS? 254 What should I bear in mind with WMS & WFS? Tools, Extensions, ArcObjects and VBA Universal test program (PrjCalculator.exe) User interface and functions The transformation task file GeographicTransformationManager - Extension for ArcMap and ArcCatalog Registering the extension The extension Edit tool for datum transformations ThefileMyGeoTra.txt VBA programming with coordinate systems Starting VBA The most important methods and properties Program steps for projecting and transformation Controlling subroutine Projection with ArcObjects Projection and datum transformation with ArcObjects Programming technique to generate a datum transformation Programming technique to generate a user defined coordinate system 280

7 XII Table of Contents Programming technique to generate a predefined coordinate system Switching intervals automatically with VBA in ArcMap Assigning coordinate systems with VBA Examples from'arcobjects Developer Help' ConvertFeatureClass with datum transformation Changing the number of decimal places in the status bar display Custom grid transformations The Geographic Transformation Environment Projecting non-point geometries The Projection Engine (PE) Calculation examples Error tolerances The influence of the transformation parameters Examples Germany: Soldner/Cassini Reproduction of a Soldner/Cassini example using ArcMap Germany: DHDN -> WGS84/ETRF Germany: S 42/83->ETRF89/ETRF89_UTM Switzerland: CH1903(+) -> WGS84 / CH > LV Sweden: RT90->SWREF99/WGS Netherlands: RD1918->WGS 1984/ RD-> UTM Czech Republic: SJTSKFerro -> S-JTSK_Ferro_ KrovakEastNorth New Zealand Map Grid -> GD New Zealand: GDI 949->NZGD Canada: NAD > NAD USA: NAD 1927-> NAD >NAD 1983(HARN) Sources of data and further information Fundamental points of geodetic grids Dimensions of important ellipsoids of rotation Published transformation parameters Reference systems datasets in ArcGIS Units and precisions URLs Concluding remarks Literature Acronymus Index 339