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Displaying Arcview Shape Files In GeoMedia When No .prj File is Present

by Technical Evangelist on ‎02-16-2016 11:58 AM - edited on ‎04-07-2016 05:38 AM by Moderator (1,005 Views)

Symptoms

The following article gives details on how to serve shape file data when no .prj file is provided.   This article also applies to all pre-2014 versions of GeoMedia even if .prj files are present.

Diagnosis

If you are using GeoMedia Desktop version 2014 or higher, and valid .prj files are present for each .shp file, GeoMedia should be able to automatically read the projection directly from the .prj files.  As for any first time warehouse connection, it's best to review the coordinate system interrepretated from the .prj files.  This can be done using Manage Data tab > Features command to Review the properties of the coordinate system assigned to the feature(s).  If the coordinate system is incorrect, consider using the workflow defined in this article.

GeoMedia requires the following files for a sucessful connection:

Graphic Features:

  • .shp
  • .shx
  • .dbf
  • .prj (optional)

Non-Graphic Features

  • .dbf

Solution

Determine the Coordinate System

GeoMedia requires information that describes the projection of the shape file data so the shape files can be transformed to the GeoWorkSpace Coordinate System correctly.

Projection information includes:

  • · Projection Name
  • · Any associated Projection Parameters
  • · Unit of Measure (m, ft, sf, deg, etc..)
  • · Horizontal Datum
  • · Vertical Datum

You need to determine the coordinate system information of the shape files from the data provider. Projection information is sometimes provided as supplementary .prj files or some other metadata files which are supplied with the standard .shp, .shx. and .dbf file structures. Any projection information supplied with the shape files should be considered ancillary to the data. They are usually correct, but since any supplied projection files are not tied to the data, you may find that the projection is occasionally incorrectly defined by the .prj or meta data files. In these cases it is suggested to contact the data vendor/provider.

Define Warehouse Configuration (.ini) File

Once the projection of the shape files is known, you can use GeoMedia’s Warehouse Configuration Utility to create an (.ini) initialization file. The .ini file allows you to define keywords that describe the data. While technically not required, it is encouraged that you consider the possibility to using the .ini file for your non-GeoMedia read-only data sources.

  • Start > All Programs > GeoMedia > Utilities > Define Warehouse Configuration File
  • Click on the Coordinate System File button to create the GeoMedia Coordinate System (.csf) File.
    • Use the tabs across the top of the Define Coordinate System dialog to define various aspects of the projection.
    • The unit of measure is defined by the Storage Space tab, Horizontal Storage Unit. For shape files the value should be 1 unit such as 1 m or 1 SF (survey foot).

Keep in mind that there is a difference between foot and survey foot. The unit defined in the .prj file may state US_FOOT but further examination shows the unit is described as 0.3048006096012192 which is the number of meters in 1 unit. Since:

1 Survey Foot (SF) = 0.3048006096012192 meters

1 International Foot (FT) = 0.3048 meters

Connecting to the Shape File Data

  1. Start GeoMedia and create a new blank GeoWorkSpace or open an existing GeoWorkSpace.
  2. Select Warehouse > New Connection and use the dialog to Specify ArcView as the connection type.
  3. Specify the folder where the shape files reside. Pay particular attention to the warehouse configuration field to ensure that it is correctly populated by the .ini file you created earlier.
  4. Right click on the map legend and use the Add option to add features to the map view. The Window > New Data Window can be used to display a non-graphic display of the data.
  5. IMPORTANT!  Confirm that the data is correctly located (geospatially); doing so now may save time and trouble later.

Trouble Shooting

If the data is incorrectly positioned then:

  1. Check the coordinate system (.csf) file defined by the .ini file . Check the unit defined by the Storage Space tab. Ensure that projection is correctly defined.

Note: If you make a change to the coordinate system (.csf) file, you must use Warehouse > Connections command to Reopen the connection or exit and reopen the GeoWorkSpace (.gws) file.

  1. Is the .ini file correctly selected when making the connection? You can use Warehouse > Connections to review the properties of the connection.

Note: The Properties button is only enabled after you select the connection (far left side of the connection name).

  1. If the file is still not correctly positioned, ensure that the .ini file is correctly defined. The format created by the Warehouse Configuration Utility is normally:

FOLDERNAME=[Full path to .csf file name]

OR

ShapeFile1=[Full path to .csf file name]

ShapeFile2=[Full path to .csf file name]

Additional Considerations:

  • When specifying any path to data, it is usually best to specify a Universal Naming Convention (UNC) path. Example: \\servername\sharename. This will make GeoWorkSpaces and GeoWorkSpace Template files easier work with throughout the network.

Easiest to organize the shape files into folders based on coordinate system. (Example: do not place shape file data of two different coordinate systems in one folder). If you must

  • place shape files of different coordinate systems, then each shape file must have its own entry in the warehouse configuration (.ini) file to define the coordinate system.
  • Be sure to select the directory containing the Arc Shape Files (.shp, .shx and .dbf) when making the connection.
  • Be sure to select the correct .ini file when making the connection.
  • Once connected, ALWAYS display some of the data and verify that it is correctly located. Methods to check that data geospatially correct:
    • Read coordinate readout field to see if values make sense.
    • Make connection to other known data (i.e. USSample.mdb) and check to see if data aligns.
  • IF, data does not align properly, exit GeoMedia and make necessary changes to the Coordinate System File (.csf) defined by the .ini file. Then reopen GeoWorkSpace to observe effect.
  • Viewing shape files in GeoMedia will cause the shape files to be locked as read-only.