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<!DOCTYPE html>

<head>

<title>Virtual Spatial Data — MapServer 8.6.1 documentation</title>

</head><body>

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<h3>Navigation</h3>

<ul>

<a href="../../genindex.html" title="General Index"

accesskey="I">index</a></li>

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accesskey="N">next</a> |</li>

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<li class="nav-item nav-item-this"><a href="">Virtual Spatial Data</a></li>

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</div>

<h1><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Virtual Spatial Data</a><a class="headerlink" href="#virtual-spatial-data" title="Link to this heading">¶</a></h1>

<dt class="field-odd">Author:</dt>

<dd class="field-odd">Jeff McKenna

</dd>

<dt class="field-even">Contact:</dt>

<dd class="field-even">jmckenna at gatewaygeomatics.com

</dd>

<dt class="field-odd">Last Updated:</dt>

<dd class="field-odd">2021-05-05

</dd>

</dl>

Table of Contents

<li><a class="reference internal" href="#virtual-spatial-data" id="id1">Virtual Spatial Data</a>

<ul>

<li><a class="reference internal" href="#types-of-databases" id="id2">Types of Databases</a></li>

<li><a class="reference internal" href="#types-of-flat-files" id="id3">Types of Flat Files</a></li>

<li><a class="reference internal" href="#steps-for-display" id="id4">Steps for Display</a></li>

</ul>

</li>

</ul>

</nav>

OGR’s <a class="reference external" href="https://gdal.org/drivers/vector/vrt.html">VRT driver</a> allows you to

connect to databases in MapServer that do not explicitly hold spatial data,

as well as flat text files. Your data must have an X and a Y column, and the data

may be accessed through an ODBC connection or a direct pointer to a text file.

The original <a class="reference external" href="https://github.com/MapServer/MapServer/wiki/VirtualSpatialData">VirtualSpatialData</a> wiki page may contain additional information.

<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Types of Databases</a><a class="headerlink" href="#types-of-databases" title="Link to this heading">¶</a></h2>

The VirtualSpatialData OGR extension has been tested with the

following databases and should, in theory, support all ODBC

data sources.

<li>Oracle</li>

<li>MySQL</li>

<li>SQL Server</li>

<li>Access</li>

<li>PostgreSQL</li>

</ul>

</section>

<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Types of Flat Files</a><a class="headerlink" href="#types-of-flat-files" title="Link to this heading">¶</a></h2>

Comma, tab or custom delimited text/flat files work with VirtualSpatialData.

</section>

<h2><a class="toc-backref" href="#table-of-contents" role="doc-backlink">Steps for Display</a><a class="headerlink" href="#steps-for-display" title="Link to this heading">¶</a></h2>

<h3>1. Create the Datasource Name (DSN)<a class="headerlink" href="#create-the-datasource-name-dsn" title="Link to this heading">¶</a></h3>

<li>Specific notes about creating a DSN on Windows and Linux can be found by

searching the MapServer reference documents site</li>

<li>On some Windows systems you must create a SYSTEM DSN.</li>

</ul>

</section>

<h3>2. Test your Connection<a class="headerlink" href="#test-your-connection" title="Link to this heading">¶</a></h3>

Test your connection with ogrinfo. The syntax for this command is:

<div class="highlight-default notranslate"><div class="highlight"><pre>> ogrinfo ODBC:user/pass@DSN table

</pre></div>

</div>

Windows users may not be required to specify a user/password, so the syntax would be:

</pre></div>

</div>

Example: Accessing a comma separated text file through ODBC using ogrinfo

The following is a snippet of the flat text file coal_dep.txt containing lat/long points:

<div class="highlight-default notranslate"><div class="highlight"><pre>unknown,na,id,id2,mark,coalkey,coalkey2,long,lat

0.000,0.000,1,1,7,87,87,76.90238,51.07161

0.000,0.000,2,2,7,110,110,78.53851,50.69403

0.000,0.000,3,3,3,112,112,83.22586,71.24420

0.000,0.000,4,4,6,114,114,80.79896,73.41175

</pre></div>

</div>

If the DSN name is Data_txt, the ogrinfo command to see a list of applicable files in the directory is:

<div class="highlight-default notranslate"><div class="highlight"><pre>> ogrinfo ODBC:jeff/test@Data_txt

INFO: Open of `ODBC:jeff/test@Data_txt'

using driver `ODBC' successful.

1: coal_dep.csv

2: coal_dep.txt

3: coal_dep_nf.txt

4: coal_dep_trim.txt

5: Copy of coal_dep.txt

6: deposit.csv

7: maruia.asc

8: oahuGISbathy.csv

9: oahuGISbathy.txt

10: on_pts.txt

11: on_pts_utm.txt

12: test.txt

13: utm_test.txt

</pre></div>

</div>

Username and password may be optional, so the following may also be valid:

</pre></div>

</div>

Therefore, the command to see more information about one of the specific layers is:

<div class="highlight-default notranslate"><div class="highlight"><pre>> ogrinfo ODBC:@Data_txt coal_dep.txt

INFO: Open of `ODBC:@Data_txt'

using driver `ODBC' successful.

Layer name: coal_dep.txt

Geometry: Unknown (any)

Feature Count: 266

Layer SRS WKT:

(unknown)

UNKNOWN: String (255.0)

NA: String (255.0)

ID: String (255.0)

ID2: String (255.0)

MARK: String (255.0)

COALKEY: String (255.0)

COALKEY2: String (255.0)

LONG: String (255.0)

LAT: String (255.0)

OGRFeature(coal_dep.txt):0

UNKNOWN (String) = 0.000

....

</pre></div>

</div>

</section>

<h3>3. Create a Virtual Data File<a class="headerlink" href="#create-a-virtual-data-file" title="Link to this heading">¶</a></h3>

This is a file with an ovf extension and looks like the following:

<SrcLayer>tablename</SrcLayer>

<GeometryType>wkbPoint</GeometryType>

</OGRVRTLayer>

</OGRVRTDataSource>

</pre></div>

</div>

More information on ovf files can be found at: <a class="reference external" href="https://gdal.org/drivers/vector/vrt.html">https://gdal.org/drivers/vector/vrt.html</a>

Example ovf file for coal_dep.txt:

<GeometryType>wkbPoint</GeometryType>

</OGRVRTLayer>

</OGRVRTDataSource>

</pre></div>

</div>

</section>

<h3>4. Test Virtual Data File with ogrinfo<a class="headerlink" href="#test-virtual-data-file-with-ogrinfo" title="Link to this heading">¶</a></h3>

Use ogrinfo to test your new ovf file, such as:

<div class="highlight-default notranslate"><div class="highlight"><pre>> ogrinfo coal.ovf coal-test

ERROR 4: Update access not supported for VRT datasources.

Had to open data source read-only.

INFO: Open of `myfile.ovf'

using driver `VRT' successful.

Layer name: coal_dep.txt

Geometry: Unknown (any)

Feature Count: 266

Layer SRS WKT:

(unknown)

UNKNOWN: String (255.0)

NA: String (255.0)

ID: String (255.0)

ID2: String (255.0)

MARK: String (255.0)

...

</pre></div>

</div>

</section>

<h3>5. Mapfile Layer<a class="headerlink" href="#mapfile-layer" title="Link to this heading">¶</a></h3>

Using an ovf file your layer may look like:

<div class="highlight-mapfile notranslate"><div class="highlight"><pre>LAYER

CONNECTION "coal.ovf"

CONNECTIONTYPE OGR

DATA "coal-test"

METADATA

"wms_srs" "4326"

"wms_title" "coal-test"

END

NAME "coal-test"

SIZEUNITS PIXELS

STATUS ON

TOLERANCE 0

TOLERANCEUNITS PIXELS

TYPE POINT

UNITS METERS

CLASS

STYLE

COLOR 255 0 0

MAXSIZE 100

MINSIZE 1

SIZE 6

SYMBOL "star"

END

</pre></div>

</div>

Note

For the CONNECTION, you can specify an absolute path, or a relative path. Relative paths

are interpreted relative to the SHAPEPATH first, if not found then MapServer will try again

relative to the .map location. For more information about connection rules please read

the MapServer <a class="reference internal" href="ogr.html#ogrmapfile">OGR</a> document.

</div>

Or you may specify the ovf contents inline such as:

<div class="highlight-default notranslate"><div class="highlight"><pre>LAYER

CONNECTION "<OGRVRTDataSource>

<GeometryType>wkbPoint</GeometryType>

</OGRVRTLayer>

</OGRVRTDataSource>"

CONNECTIONTYPE OGR

DATA "coal-test"

METADATA

"wms_srs" "4326"

"wms_title" "coal-test"

END

NAME "coal-test"

SIZEUNITS PIXELS

STATUS ON

TOLERANCE 0

TOLERANCEUNITS PIXELS

TYPE POINT

UNITS METERS

CLASS

STYLE

COLOR 255 0 0

MAXSIZE 100

MINSIZE 1

SIZE 6

SYMBOL "star"

END

</pre></div>

</div>

</section>

<h3>6. Test your Mapfile<a class="headerlink" href="#test-your-mapfile" title="Link to this heading">¶</a></h3>

The first thing you should try is to use the <a class="reference internal" href="../../utilities/map2img.html#map2img">map2img</a> utility:

<div class="highlight-default notranslate"><div class="highlight"><pre>map2img -m mymapfile.map -o test.png

</pre></div>

</div>

Once you successfully created a map image, then try your application. Note

Windows users may come across a problem where map2img works but their

application throws an error similar to this:

<div class="highlight-default notranslate"><div class="highlight"><pre>Warning: [MapServer Error]: msOGRFileOpen(): Open failed for OGR connection `coal.ovf'.

Unable to initialize ODBC connection to DSN for jeff/test@Data_txt,

[Microsoft][ODBC Driver Manager] Data source name not found

and no default driver specified in D:\ms4w\Apache\htdocs\quickmap.php on line 40

</pre></div>

</div>

If that happens you should make sure you have created a System DSN.

</section>

</div>

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<h3>Current Table Of Contents</h3>

<ul>

<li><a class="reference internal" href="#">Virtual Spatial Data</a><ul>

<li><a class="reference internal" href="#types-of-databases">Types of Databases</a></li>

<li><a class="reference internal" href="#types-of-flat-files">Types of Flat Files</a></li>

<li><a class="reference internal" href="#steps-for-display">Steps for Display</a><ul>

<li><a class="reference internal" href="#create-the-datasource-name-dsn">1. Create the Datasource Name (DSN)</a></li>

<li><a class="reference internal" href="#test-your-connection">2. Test your Connection</a></li>

<li><a class="reference internal" href="#create-a-virtual-data-file">3. Create a Virtual Data File</a></li>

<li><a class="reference internal" href="#test-virtual-data-file-with-ogrinfo">4. Test Virtual Data File with ogrinfo</a></li>

<li><a class="reference internal" href="#mapfile-layer">5. Mapfile Layer</a></li>

<li><a class="reference internal" href="#test-your-mapfile">6. Test your Mapfile</a></li>

</ul>

</li>

</ul>

</li>

</ul>

</div>

</div>

<h3>Navigation</h3>

<ul>

<a href="../../genindex.html" title="General Index"

>index</a></li>

<a href="wfs.html" title="WFS"

>next</a> |</li>

<a href="vector_field.html" title="Vector field rendering - UVraster"

>previous</a> |</li>

<li class="nav-item nav-item-1"><a href="../../documentation.html" >MapServer 8.6.1 Documentation</a> »</li>

<li class="nav-item nav-item-2"><a href="../index.html" >Data Input</a> »</li>

<li class="nav-item nav-item-3"><a href="index.html" >Vector Data</a> »</li>

<li class="nav-item nav-item-this"><a href="">Virtual Spatial Data</a></li>

</ul>

</div>

Last updated on 2026-03-30.

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