B.2. Data Format Guide

B.2. Data Format Guide

The rest of this document is the data format guide. This guide is structured to show the fundamentals of each MapServer-supported data format. Each section discusses one format, ranging from one to several pages in length. The sections typically start with a summary of the most important information about the format, followed by examples of file listings, connection methods , ogrinfo usage, and MapServer map file syntax examples.

Each section has been designed to stand alone, so you may notice that certain warnings and comments are repeated or redundant. This is intentional. Each format is presented in rough order of popular use, based on a survey of the MapServer community.

The following formats are included:

• ESRI shapefiles (SHP)

• PostGIS/PostgreSQL database

• MapInfo files (TAB/MID/MIF)

• Oracle Spatial Database

• Web Feature Service (WFS)

• Geography Markup Language (GML)

• VirtualSpatialData (ODBC/OVF)

• TIGER/Line files

• ESRI Arc Info coverage files (ADF)

• ESRI ArcSDE database (SDE)

• Microstation design files (DGN)

• IHO S-57 files

• Spatial Data Transfer Standard files (SDTS)

• Inline MapServer features

• National Transfer Format files (NTF)

The MySQL spatial database isn't covered in this guide at this time due to lack of familiarity by the authors. Future contributions by MySQL users are welcome in this guide.

Also known as ESRI ArcView. ESRI is the company that introduced this format; ArcView was the first product to use shapefiles.

File listing

Shapefiles are made up of a minimum of three similarly named files, with different suffixes:

Countries_area.dbf

Countries_area.shp

Countries_area.shx

Data access/connection method

• Shapefile access is built directly into MapServer. It is also available through OGR, but direct access without OGR is recommended and discussed here.

• The path to the shapefile is required. No file extension should be specified.

• Shapefiles hold only one layer of data, therefore no distinction needs to be made.

ogrinfo examples

• The directory can serve as a data source.

• Each shapefile in a directory serves as a layer.

• A shapefile can also be a data source. In this case the layer has the same prefix as the shapefile.

Here's an example that uses ogrinfo on a directory with multiple shapefiles:

> ogrinfo /data/shapefiles/

INFO: Open of '/data/shapefiles/'

    using driver 'ESRI Shapefile' successful.

    1: wpg_h2o (Line String)

    2: wpg_roads (Line String)

    3: wpg_roads_dis (Line String)

    4: wpgrestaurants (Point)

Here's an example that uses ogrinfo on a single shapefile:

> ogrinfo /data/shapefiles/Countries_area.shp

Had to open data source read-only.

    INFO: Open of 'Countries_area.shp'

    using driver 'ESRI Shapefile' successful.

    1: Countries_area (Polygon)

Here's an example that uses ogrinfo to examine the structure of the file/layer:

> ogrinfo -summary /data/shapefiles/Countries_area.shp Countries_area

Had to open data source read-only.

    INFO: Open of 'Countries_area.shp'

    using driver 'ESRI Shapefile' successful.

     

    Layer name: Countries_area

    Geometry: Polygon

    Feature Count: 27458

    Extent: (-180.000000, -90.000000) - (180.000000, 83.627419)

    Layer SRS WKT:

    (unknown)

    FAC_ID: Integer (5.0)

    TILE: Integer (3.0)

    ARCLIST: String (254.0)

    NAM: String (77.0)

    PERIMETER: Real (22.17)

    POLYGONCOU: Integer (6.0)

    NA2DESC: String (45.0)

Map file example

LAYER

      NAME my_shapefile

      TYPE POLYGON

      DATA countries_area

      STATUS OFF

      CLASS

        NAME "Countries"

        OUTLINECOLOR 0 0 0

      END

    END