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LAYERΒΆ

CLASS

Signals the start of a CLASS object.

Inside a layer, only a single class will be used for the rendering of a feature. Each feature is tested against each class in the order in which they are defined in the mapfile. The first class that matches the its min/max scale constraints and its EXPRESSION check for the current feature will be used for rendering.

CLASSGROUP [string]
Specify the class’s group that would be considered at rendering time. The CLASS object’s GROUP parameter must be used in combination with CLASSGROUP.
CLASSITEM [attribute]
Item name in attribute table to use for class lookups.
CLUSTER

Signals the start of a CLUSTER object.

The CLUSTER configuration option provides to combine multiple features from the layer into single (aggregated) features based on their relative positions. Supported only for POINT layers.

CONNECTION [string]

Database connection string to retrieve remote data.

An SDE connection string consists of a hostname, instance name, database name, username and password separated by commas.

A PostGIS connection string is basically a regular PostgreSQL connection string, it takes the form of “user=nobody password=****** dbname=dbname host=localhost port=5432”

An Oracle connection string: user/pass[@db]

See also

Vector Data for specific connection information for various data sources.

CONNECTIONTYPE [contour|local|ogr|oraclespatial|plugin|postgis|sde|union|uvraster|wfs|wms]

Type of connection. Default is local. See additional documentation for any other type.

See also

Vector Data for specific connection information for various data sources. See Union Layer for combining layers, added in MapServer 6.0

Note

mygis is another connectiontype, but it is deprecated; please see the MySQL section of the Vector Data document for connection details.

DATA [filename]|[sde parameters][postgis table/column][oracle table/column]

Full filename of the spatial data to process. No file extension is necessary for shapefiles. Can be specified relative to the SHAPEPATH option from the Map Object.

If this is an SDE layer, the parameter should include the name of the layer as well as the geometry column, i.e. “mylayer,shape,myversion”.

If this is a PostGIS layer, the parameter should be in the form of “<columnname> from <tablename>”, where “columnname” is the name of the column containing the geometry objects and “tablename” is the name of the table from which the geometry data will be read.

For Oracle, use “shape FROM table” or “shape FROM (SELECT statement)” or even more complex Oracle compliant queries! Note that there are important performance impacts when using spatial subqueries however. Try using MapServer’s FILTER whenever possible instead. You can also see the SQL submitted by forcing an error, for instance by submitting a DATA parameter you know won’t work, using for example a bad column name.

See also

Vector Data for specific connection information for various data sources.

DEBUG [off|on|0|1|2|3|4|5]

Enables debugging of a layer in the current map.

Debugging with MapServer versions >= 5.0:

Verbose output is generated and sent to the standard error output (STDERR) or the MapServer errorfile if one is set using the “MS_ERRORFILE” environment variable. You can set the environment variable by using the CONFIG parameter at the MAP level of the mapfile, such as:

CONFIG "MS_ERRORFILE" "/ms4w/tmp/ms_error.txt"

You can also set the environment variable in Apache by adding the following to your httpd.conf:

SetEnv MS_ERRORFILE "/ms4w/tmp/ms_error.txt"

Once the environment variable is set, the DEBUG mapfile parameter can be used to control the level of debugging output. Here is a description of the possible DEBUG values:

  • DEBUG O or OFF - only msSetError() calls are logged to MS_ERRORFILE. No msDebug() output at all. This is the default and corresponds to the original behavior of MS_ERRORFILE in MapServer 4.x
  • DEBUG 1 or ON - includes all output from DEBUG 0 plus msDebug() warnings about common pitfalls, failed assertions or non-fatal error situations (e.g. missing or invalid values for some parameters, missing shapefiles in tileindex, timeout error from remote WMS/WFS servers, etc.)
  • DEBUG 2 - includes all output from DEBUG 1 plus notices and timing information useful for tuning mapfiles and applications
  • DEBUG 3 - all of DEBUG 2 plus some debug output useful in troubleshooting problems such as WMS connection URLs being called, database connection calls, etc. This is the recommended level for debugging mapfiles.
  • DEBUG 4 - DEBUG 3 plus even more details...
  • DEBUG 5 - DEBUG 4 plus any msDebug() output that might be more useful to the developers than to the users.

You can also set the debug level by using the “MS_DEBUGLEVEL” environment variable.

The DEBUG setting can also be specified for the entire map, by setting the DEBUG parameter in the MAP object.

For more details on this debugging mechanism, please see MS RFC 28: Redesign of LOG/DEBUG output mechanisms.

Debugging with MapServer versions < 5:

Verbose output is generated and sent to the standard error output (STDERR) or the MapServer logfile if one is set using the LOG parameter in the WEB object. Apache users will see timing details for drawing in Apache’s error_log file. Requires MapServer to be built with the DEBUG=MSDEBUG option (–with-debug configure option).

DUMP [true|false]

Since 6.0, DUMP is not used anymore. LAYER METADATA is used instead.

Switch to allow MapServer to return data in GML format. Useful when used with WMS GetFeatureInfo operations. “false” by default.

Deprecated since version 6.0: LAYER METADATA is used instead.

See also

WMS Server

EXTENT [minx] [miny] [maxx] [maxy]
The spatial extent of the data. In most cases you will not need to specify this, but it can be used to avoid the speed cost of having MapServer compute the extents of the data. An application can also possibly use this value to override the extents of the map.
FEATURE
Signals the start of a FEATURE object.
FILTER [string]

This parameter allows for data specific attribute filtering that is done at the same time spatial filtering is done, but before any CLASS expressions are evaluated. For OGR and shapefiles the string is simply a mapserver regular expression. For spatial databases the string is a SQL WHERE clause that is valid with respect to the underlying database.

For example: FILTER ([type]=’road’ and [size]<2)

FILTERITEM [attribute]
Item to use with simple FILTER expressions. OGR and shapefiles only.
FOOTER [filename]
Template to use after a layer’s set of results have been sent. Multiresult query modes only.
GEOMTRANSFORM [<expression>]

Used to indicate that the current feature will be transformed. Introduced in version 6.4.

  • <expression>: Applies the given expression to the geometry.

    Supported expressions:

    • (buffer([shape],dist)): Buffer the geometry ([shape]) using dist pixels as buffer distance. For polygons, a negative dist will produce a setback.
    • (simplify([shape],tolerance)): simplifies a geometry ([shape]) using the standard Douglas-Peucker algorithm.
    • (simplifypt([shape], tolerance)): simplifies a geometry ([shape]), ensuring that the result is a valid geometry having the same dimension and number of components as the input. tolerance must be non-negative.

There is a difference between STYLE and LAYER GEOMTRANSFORM. LAYER-level will receive ground coordinates (meters, degress, etc) and STYLE-level will receive pixel coordinates. The argument to methods such as simplify() must be in the same units as the coordinates of the shapes at that point of the rendering workflow, i.e. pixels at the STYLE-level and in ground units at the LAYER-level.

LAYER NAME "my_layer"
    TYPE LINE
    STATUS DEFAULT
    DATA "lines.shp"
    GEOMTRANSFORM (simplify([shape], 10))  ## 10 ground units
    CLASS
        STYLE
            GEOMTRANSFORM (buffer([shape], 5)  ## 5 pixels
            WIDTH 2
            COLOR 255 0 0
        END
    END
END

The [map_cellsize] variable is available if you need to pass a pixel value at the LAYER-level.

LAYER NAME "my_layer"
    TYPE LINE
    STATUS DEFAULT
    DATA "lines.shp"
    UNITS meters
    # 10 * [map_cellsize] == 10 pixels converted to ground units
    GEOMTRANSFORM (simplify([shape], [map_cellsize]*10))
...

To get this variable working in the math expression parser, the [map_cellsize] has to be converted into the layer ground unit. If you choose to use [map_cellsize] in your GEOMTRANSFORM expression, you must explicitly set the UNITS option in the layer.

GRID
Signals the start of a GRID object.
GROUP [name]

Name of a group that this layer belongs to. The group name can then be reference as a regular layer name in the template files, allowing to do things like turning on and off a group of layers at once.

If a group name is present in the LAYERS parameter of a CGI request, all the layers of the group are returned (the STATUS of the LAYERs have no effect).

HEADER [filename]
Template to use before a layer’s set of results have been sent. Multiresult query modes only.
JOIN
Signals the start of a JOIN object.
LABELANGLEITEM [attribute]

(As of MapServer 5.0 this parameter is no longer available. Please see the LABEL object’s ANGLE parameter) For MapServer versions < 5.0, this is the item name in attribute table to use for class annotation angles. Values should be in degrees.

Deprecated since version 5.0.

LABELCACHE [on|off]
Specifies whether labels should be drawn as the features for this layer are drawn, or whether they should be cached and drawn after all layers have been drawn. Default is on. Label overlap removal, auto placement etc... are only available when the label cache is active.
LABELITEM [attribute]
Item name in attribute table to use for class annotation (i.e. labeling).
LABELMAXSCALEDENOM [double]

Minimum scale at which this LAYER is labeled. Scale is given as the denominator of the actual scale fraction, for example for a map at a scale of 1:24,000 use 24000. Implemented in MapServer 5.0, to replace the deprecated LABELMAXSCALE parameter.

See also

Map Scale

LABELMINSCALEDENOM [double]

Maximum scale at which this LAYER is labeled. Scale is given as the denominator of the actual scale fraction, for example for a map at a scale of 1:24,000 use 24000. Implemented in MapServer 5.0, to replace the deprecated LABELMINSCALE parameter.

See also

Map Scale

LABELREQUIRES [expression]

Sets context for labeling this layer, for example:

LABELREQUIRES "![orthoquads]"

means that this layer would NOT be labeled if a layer named “orthoquads” is on. The expression consists of a boolean expression based on the status of other layers, each [layer name] substring is replaced by a 0 or a 1 depending on that layer’s STATUS and then evaluated as normal. Logical operators AND and OR can be used.

LABELSIZEITEM [attribute]

(As of MapServer 5.0 this parameter is no longer available. Please see the LABEL object’s SIZE parameter) For MapServer versions < 5.0, this is the item name in attribute table to use for class annotation sizes. Values should be in pixels.

Deprecated since version 5.0.

MASK [layername]

The data from the current layer will only be rendered where it intersects features from the [layername] layer. [layername] must reference the NAME of another LAYER defined in the current mapfile. can be any kind of mapserver layer, i.e. vector or raster. If the current layer has labelling configured, then only labels who’s label-point fall inside the unmasked area will be added to the labelcache (the actual glyphs for the label may be rendered ontop of the masked-out area.

Note

Unless you want the features of [layername] to actually appear on the generated map, [layername] should usually be set to STATUS OFF.

MAXFEATURES [integer]
Specifies the number of features that should be drawn for this layer in the CURRENT window. Has some interesting uses with annotation and with sorted data (i.e. lakes by area).
MAXGEOWIDTH [double]

Maximum width, in the map’s geographic units, at which this LAYER is drawn. If MAXSCALEDENOM is also specified then MAXSCALEDENOM will be used instead.

The width of a map in geographic units can be found by calculating the following from the extents:

[maxx] - [minx]

New in version 5.4.0.

MAXSCALEDENOM [double]

Minimum scale at which this LAYER is drawn. Scale is given as the denominator of the actual scale fraction, for example for a map at a scale of 1:24,000 use 24000.

New in version 5.0.0: Replaced MAXSCALE.

See also

Map Scale

METADATA

This keyword allows for arbitrary data to be stored as name value pairs. This is used with OGC WMS to define things such as layer title. It can also allow more flexibility in creating templates, as anything you put in here will be accessible via template tags.

Example:

METADATA
    "title" "My layer title"
    "author" "Me!"
END

MINGEOWIDTH [double]

Minimum width, in the map’s geographic units, at which this LAYER is drawn. If MINSCALEDENOM is also specified then MINSCALEDENOM will be used instead.

The width of a map in geographic units can be found by calculating the following from the extents:

[maxx] - [minx]

New in version 5.4.0.

MINSCALEDENOM [double]

Maximum scale at which this LAYER is drawn. Scale is given as the denominator of the actual scale fraction, for example for a map at a scale of 1:24,000 use 24000. Implemented in MapServer 5.0, to replace the deprecated MINSCALE parameter.

See also

Map Scale

NAME [string]
Short name for this layer. This name is the link between the mapfile and web interfaces that refer to this name. They must be identical. The name should be unique, unless one layer replaces another at different scales. Use the GROUP option to associate layers with each other. It is recommended that the name not contain spaces, special characters, or begin with a number (which could cause problems through interfaces such as OGC services).
OFFSITE [r] [g] [b]
Sets the color index to treat as transparent for raster layers.
OPACITY [integer|alpha]

Sets the opacity level (or the inability to see through the layer) of all classed pixels for a given layer. The value can either be an integer in the range (0-100) or the named symbol “ALPHA”. A value of 100 is opaque and 0 is fully transparent. Implemented in MapServer 5.0, to replace the deprecated TRANSPARENCY parameter.

The “ALPHA” symbol directs the MapServer rendering code to honor the indexed or alpha transparency of pixmap symbols used to style a layer. This is only needed in the case of RGB output formats, and should be used only when necessary as it is expensive to render transparent pixmap symbols onto an RGB map image.

PLUGIN [filename]

Additional library to load by MapServer, for this layer. This is commonly used to load specific support for SDE and Microsoft SQL Server layers, such as:

CONNECTIONTYPE PLUGIN
CONNECTION "hostname,port:xxx,database,username,password"
PLUGIN "C:/ms4w/Apache/specialplugins/msplugin_sde_92.dll"
DATA "layername,geometrycolumn,SDE.DEFAULT"
POSTLABELCACHE [true|false]
Tells MapServer to render this layer after all labels in the cache have been drawn. Useful for adding neatlines and similar elements. Default is false.
PROCESSING [string]

Passes a processing directive to be used with this layer. The supported processing directives vary by layer type, and the underlying driver that processes them.

  • Attributes Directive - The ITEMS processing option allows to specify the name of attributes for inline layers or specify the subset of the attributes to be used by the layer, such as:

    PROCESSING "ITEMS=itemname1,itemname2,itemname3"
    
  • Connection Pooling Directive - This is where you can enable connection pooling for certain layer layer types. Connection pooling will allow MapServer to share the handle to an open database or layer connection throughout a single map draw process. Additionally, if you have FastCGI enabled, the connection handle will stay open indefinitely, or according to the options specified in the FastCGI configuration. Oracle Spatial, ArcSDE, OGR and PostGIS/PostgreSQL currently support this approach.

    PROCESSING "CLOSE_CONNECTION=DEFER"
    
  • Label Directive - The LABEL_NO_CLIP processing option can be used to skip clipping of shapes when determining associated label anchor points. This avoids changes in label position as extents change between map draws. It also avoids duplicate labels where features appear in multiple adjacent tiles when creating tiled maps.

    PROCESSING "LABEL_NO_CLIP=True"
    
  • Line Rendering Directive - The POLYLINE_NO_CLIP processing option can be used to skip clipping of shapes when rendering styled lines (dashed or styled with symbols). This avoids changes in the line styling as extents change between map draws. It also avoids edge effects where features appear in multiple adjacent tiles when creating tiled maps.

    PROCESSING "POLYLINE_NO_CLIP=True"
    
  • OGR Styles Directive - This directive can be used for obtaining label styles through MapScript. For more information see the MapServer’s OGR document.

    PROCESSING "GETSHAPE_STYLE_ITEMS=all"
    
  • Raster Directives - All raster processing options are described in Raster Data. Here we see the SCALE and BANDs directives used to autoscale raster data and alter the band mapping.

    PROCESSING "SCALE=AUTO"
    PROCESSING "BANDS=3,2,1"
    
PROJECTION
Signals the start of a PROJECTION object.
REQUIRES [expression]
Sets context for displaying this layer (see LABELREQUIRES).
SIZEUNITS [feet|inches|kilometers|meters|miles|nauticalmiles|pixels]
Sets the unit of CLASS object SIZE values (default is pixels). Useful for simulating buffering. nauticalmiles was added in MapServer 5.6.
STATUS [on|off|default]

Sets the current status of the layer. Often modified by MapServer itself. Default turns the layer on permanently.

Note

In CGI mode, layers with STATUS DEFAULT cannot be turned off using normal mechanisms. It is recommended to set layers to STATUS DEFAULT while debugging a problem, but set them back to ON/OFF in normal use.

Note

For WMS, layers in the server mapfile with STATUS DEFAULT are always sent to the client.

Note

The STATUS of the individual layers of a GROUP has no effect when the group name is present in the LAYERS parameter of a CGI request - all the layers of the group will be returned.

STYLEITEM [<attribute>|auto]

Item to use for feature specific styling. The style information may be represented by a separate attribute (style string) attached to the feature. MapServer supports the following style string representations:

  • MapServer STYLE definition - The style string can be represented as a MapServer STYLE block according to the following example:

    STYLE BACKGROUNDCOLOR 128 0 0 COLOR 0 0 208 END
    
  • MapServer CLASS definition - By specifying the entire CLASS instead of a single style allows to use further options (like setting expressions, label attributes, multiple styles) on a per feature basis.

  • OGR Style String - MapServer support rendering the OGR style string format according to the OGR - Feature Style Specification documentation. Currently only a few data sources support storing the styles along with the features (like MapInfo, AutoCAD DXF, Microstation DGN), however those styles can easily be transferred to many other data sources as a separate attribute by using the ogr2ogr command line tool as follows:

    ogr2ogr -sql "select *, OGR_STYLE from srclayer" "dstlayer" "srclayer"

The value: AUTO can be used for automatic styling.

  • Automatic styling can be provided by the driver. Currently, only the OGR driver supports automatic styling.
  • When used for a Union Layer, the styles from the source layers will be used.
SYMBOLSCALEDENOM [double]

The scale at which symbols and/or text appear full size. This allows for dynamic scaling of objects based on the scale of the map. If not set then this layer will always appear at the same size. Scaling only takes place within the limits of MINSIZE and MAXSIZE as described above. Scale is given as the denominator of the actual scale fraction, for example for a map at a scale of 1:24,000 use 24000. Implemented in MapServer 5.0, to replace the deprecated SYMBOLSCALE parameter.

See also

Map Scale

TEMPLATE [file|url]
Used as a global alternative to CLASS TEMPLATE. See Templating for more info.
TILEINDEX [filename|layername]

Name of the tileindex file or layer. A tileindex is similar to an ArcInfo library index. The tileindex contains polygon features for each tile. The item that contains the location of the tiled data is given using the TILEITEM parameter. When a file is used as the tileindex for shapefile or raster layers, the tileindex should be a shapefile. For CONNECTIONTYPE OGR layers, any OGR supported datasource can be a tileindex. Normally the location should contain the path to the tile file relative to the shapepath, not relative to the tileindex itself. If the DATA parameter contains a value then it is added to the end of the location. When a tileindex layer is used, it works similarly to directly referring to a file, but any supported feature source can be used (ie. postgres, oracle).

Note

All files in the tileindex should have the same coordinate system, and for vector files the same set of attributes in the same order.

Note

Starting with MapServer 6.4, raster layers can use a tileindex with tiles of different projections. For that, the TILESRS parameter must be specified.

TILEITEM [attribute]
Item that contains the location of an individual tile, default is “location”.
TILESRS [attribute]

Name of the attribute that contains the SRS of an individual tile. That SRS can be expressed in WKT format, as an EPSG:XXXX code or as a PROJ.4 string. If the tileindex contains rasters in different projections, this option must be specified. If the tileindex has been generated with gdaltindex (GDAL >= 2.0), the value of TILESRS is the value of the -src_srs_name option of gdaltindex. See Tileindexes with tiles in different projections

Note

This option is currently available only on raster layers.

TOLERANCE [double]
Sensitivity for point based queries (i.e. via mouse and/or map coordinates). Given in TOLERANCEUNITS. If the layer is a POINT or a LINE, the default is 3. For all other layer types, the default is 0. To restrict polygon searches so that the point must occur in the polygon set the tolerance to zero. This setting does not apply to WFS GetFeature operations.
TOLERANCEUNITS [pixels|feet|inches|kilometers|meters|miles|nauticalmiles|dd]
Units of the TOLERANCE value. Default is pixels. Nauticalmiles was added in MapServer 5.6.

TRANSPARENCY [integer|alpha] - deprecated

Deprecated since version 5.0: Use OPACITY instead.

TRANSFORM [true|false ul|uc|ur|lc|cc|lr|ll|lc|lr]

Tells MapServer whether or not a particular layer needs to be transformed from some coordinate system to image coordinates. Default is true. This allows you to create shapefiles in image/graphics coordinates and therefore have features that will always be displayed in the same location on every map. Ideal for placing logos or text in maps. Remember that the graphics coordinate system has an origin in the upper left hand corner of the image, contrary to most map coordinate systems.

Version 4.10 introduces the ability to define features with coordinates given in pixels (or percentages, see UNITS), most often inline features, relative to something other than the UL corner of an image. That is what ‘TRANSFORM FALSE’ means. By setting an alternative origin it allows you to anchor something like a copyright statement to another portion of the image in a way that is independent of image size.

TYPE [chart|circle|line|point|polygon|raster|query]

Specifies how the data should be drawn. Need not be the same as the shapefile type. For example, a polygon shapefile may be drawn as a point layer, but a point shapefile may not be drawn as a polygon layer. Common sense rules.

In order to differentiate between POLYGONs and POLYLINEs (which do not exist as a type), simply respectively use or omit the COLOR keyword when classifying. If you use it, it’s a polygon with a fill color, otherwise it’s a polyline with only an OUTLINECOLOR.

A circle must be defined by a a minimum bounding rectangle. That is, two points that define the smallest square that can contain it. These two points are the two opposite corners of said box. The following is an example using inline points to draw a circle:

LAYER
  NAME 'inline_circles'
  TYPE CIRCLE
  STATUS ON
  FEATURE
    POINTS
      74.01 -53.8
      110.7 -22.16
    END
  END
  CLASS
    STYLE
      COLOR 0 0 255
    END
  END
END

TYPE query means the layer can be queried but not drawn.

Note

TYPE annotation has been deprecated since version 6.2. Identical functionality can be obtained by adding LABEL level STYLE blocks, and do not require loading the datasets twice in two different layers as was the case with layers of TYPE annotation.

See also

The Dynamic Charting HowTo for TYPE chart.

UNITS [dd|feet|inches|kilometers|meters|miles|nauticalmiles|percentages|pixels]
Units of the layer. percentages (in this case a value between 0 and 1) was added in MapServer 4.10 and is mostly geared for inline features. nauticalmiles was added in MapServer 5.6.
VALIDATION

Signals the start of a VALIDATION block.

As of MapServer 5.4.0, VALIDATION blocks are the preferred mechanism for specifying validation patterns for CGI param runtime substitutions. See Run-time Substitution.

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