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Civil Engineering Transportation GIS Workshop

workshop guide

Lab Exercise: Geometric Calculation Differences

  1. Start ArcMap.
  2. Check data frame's coordinate system: within Table of Contents, double click Data Frame to open Data Frame Properties. Click Coordinate System tab - there is no coordinate system identified.
  3. Add data: ...MapProjections\DMTI_Roads_Calgary
  4. Check the layer's coordinate system: double click the data layer to open the Layer Properties. Click the Source tab - take note of the geographic coordinate system. 
  5. Check data frame's coordinate system: the data frame adopted the coordinate system of the (first) added data layer.
  6. Select NAD_1983_UTM_Zone_11N as the projected coordinate system. To execute geometric calculations (e.g. shape length) a projection needs to be identified (in data frame or set as part of the data layer). 
  7. Set Transformation:
    • Convert from: GCS_WGS_1984
    • Into: GCS_North_America_1983
    • Using: WGS_1984_(ITRF00)_To_NAD_1983
  8. Add Field: Open Attribute Table of the data layer, from Table Options select Add Field (name - RoadLength, Type - Double).
  9. Run Calculate Geometry in the newly created field. Set Property - Length and select Use coordinate system of data frame
  10. Compare fields the two length fields. If you want the geometry to persist as part of the data layer, run Project (Data Management) Tool.

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