Backdrop Maps

Backdrop maps are auxiliary graphic data lying under the graphic presentation of the active data – features. They can be both vector and raster (special case of raster backdrop is binaryRasterBackdropType). Every backdrop map has its definition (backdrop type) in the metadata. Every backdrop map can be provided in various formats and structures, so called layers. The definitions are grouped together in backdropTypeArray collection.

General structure of backdrop is:

Attributes

id – Unique identifier of a backdrop.
name – Name of a backdrop.
versioned – Boolean. If true, it is used for recording changes and for „creating history“.
colorModelType="rgb/rgba/greyscale/palette". If specified, only raster files having this color model may be inserted into the layer.

Inner Elements

description – Contains a detailed description of the group container.
featureType – Reference to a related feature type.
layerArray – Type of backdrop layer (mainTilledLayer/tilledLayer/plainLayer for raster backdrop, tilledLayer/plainLayer for vector backdrop).
symbology – For example color and opacity of backdrop.
dynamicSymbology – Reference to symbology in thematization.xml.

Example: Structure of a backdrop type.

    <ber:vectorBackdropType id="bd_01" name="Overview map" versioned="true">
      <ber:description>More detailed vector backdrop</ber:description>
      <ber:layerArray>
        <ber:tiledLayer id="lay_bd_01_dgn" name="DGN overview map" format="dgn"/>
        <ber:tiledLayer id="lay_bd_01_dwg" name="DWG overview map" format="dwg"/>
      </ber:layerArray>
    </ber:vectorBackdropType>

Vector Backdrop Maps

Vector backdrop types can have several vector layers. Supported formats for vector files are DGN, DWG, DXF, SHP and SVG. Vector layers can be only tiled, which means that the layer is represented by files covering a specified area using the tile structure. Tiles are of various sizes and can overlap. Tiles of a particular layer need not create a continuous coverage.

Each backdrop map definition can specify its symbology. It can be either static (the same for all scales) or dynamic (allows define visibility for scales and symbology according to element properties for vector backdrop maps). Every backdrop type can define one default static and one default dynamic symbology. While the static symbology is the part of the backdrop map definition, the dynamic symbology refers special LIDS metadata section (in thematization.xml).

Example: Vector backdrop map definition.

<ber:backdropTypeArray>
  <!-- More detailed vector backdrop -->
  <ber:vectorBackdropType id="bd_01" name="Overview map">
    <ber:description>More detailed vector backdrop</ber:description>
    <ber:layerArray>
      <ber:tiledLayer id="lay_bd_01_dgn" name="DGN overview map"
                      format="dgn"/>
      <ber:tiledLayer id="lay_bd_01_dwg" name="DWG overview map"
                      format="dwg"/>
    </ber:layerArray>
    <!—Static symbology -->
    <ber:simpleVectorSymbolizer>
      <se:Opacity>0.5</se:Opacity>
    </ber:simpleVectorSymbolizer>
    <!—Reference to the dynamic symbology -->
    <ber:dynamicSymbology xlink:href="thematization.xml#bs_01" />
  </ber:vectorBackdropType>
  ...
</ber:backdropTypeArray>

Dynamic symbology

Dynamic symbology is defined in the thematization.xml metadata part. It consists of 2 parts:

visibility based on the scales (optional) – if not set it is visible
symbology (common for all scales)
simple symbolizer (color and / or transparency) used for all elements
symbology based on classification according element properties

Example: Vector backdrop dynamic symbology (part of thematization.xml).

<ber:vectorBackdropStyle id="bs_01" name="Colored by level and geometry type">
  <!—Visibility according to scales -->
  <ber:scaleRules hiddenDefault="false">
    <ber:scaleOnlyRule hiddenScale="true">
      <se:MinScaleDenominator>500</se:MinScaleDenominator>
      <se:MaxScaleDenominator>2000</se:MaxScaleDenominator>
    </ber:scaleOnlyRule>
  </ber:scaleRules>
  <!— Classification rules -->
  <ber:vectorRule id="bs_01_r1" name="Shape in STREET level">
    <ogc:Filter>
      <ogc:PropertyIsEqualTo>
        <ogc:PropertyName>element.level</ogc:PropertyName>
        <ogc:Literal>Street</ogc:Literal>
      </ogc:PropertyIsEqualTo>
    </ogc:Filter>
    <ber:polygonSymbolizer>
      <ber:fill>
        <ber:fillStyle>none</ber:fillStyle>
      </ber:fill>
      <se:Stroke>
        <se:SvgParameter name="stroke">#0000FF</se:SvgParameter>
      </se:Stroke>
    </ber:polygonSymbolizer>
  </ber:vectorRule>
  <ber:vectorRule id="bs_01_r2" name="Cells are replaced by symbol">
    <ogc:Filter>
      <ogc:PropertyIsEqualTo>
        <ogc:PropertyName>element.type</ogc:PropertyName>
        <ogc:Literal>Cell</ogc:Literal>
      </ogc:PropertyIsEqualTo>
    </ogc:Filter>
    <ber:pointSymbolizer>
      <se:Graphic>
        <se:ExternalGraphic>
          <se:OnlineResource
                xlink:href="resource.xml#ber_LIDSdemo/66/center-center" />
          <se:Format />
        </se:ExternalGraphic>
      </se:Graphic>
      <ber:rgbColor>#00FF00</ber:rgbColor>
      <ber:symbolHeight>4</ber:symbolHeight>
    </ber:pointSymbolizer>
  </ber:vectorRule>
</ber:vectorBackdropStyle>

PropertyName: These values are supported: file.format, element.type, element.level, element.color, line.style, line.weight, font.name, cell.name
Literal – Possible values in case of PropertyName= element.type: Point, Ellipse, EllipseArc, Line, Polyline, Multiline, Polygon, Spline, Text, TextNode, LineString, ComplexString, Dimension, Shape, ComplexShape, Cell.

Raster Backdrop Maps

Raster backdrop type can have several layers. Each layer has format and structure. Supported raster formats are TIFF, JPEG, PNG, CIT, COT, HMR, BMP and GIF. Raster backdrop layers can have tiled (main tiled), hierarchical or plain structure.

tip

If raster backdrop type contains monochromatic raster files only it should be defined as a special type of backdrop type - binaryRasterBackdropType. It allows to define color and transparency for both foreground and background.

Example: Raster backdrop map definition.

<ber:backdropTypeArray>
  <ber:rasterBackdropType id="bd_02" name="Orthophoto">
    <ber:description>Hierarchical orthophoto raster</ber:description>
    <ber:layerArray>
      <ber:mainTiledLayer id="lay_bd_02_tiff" name="TIFF Orthophoto"
                          format="tiff">
        <ber:hierarchicalLayer id="lay_bd_02_jpeg" name="JPEG Orthophoto"
                               format="jpeg">
          <ber:hierarchy decreaseRatio="3"
                         tileWidth="1000"
                         tileHeight="1000"/>
        </ber:hierarchicalLayer>
      </ber:mainTiledLayer>
    </ber:layerArray>
  </ber:rasterBackdropType>
  <ber:rasterBackdropType id="bd_10" name="External WMS">
    <ber:description>Germany GNU FDL/PGL</ber:description>
    <ber:layerArray>
      <ber:plainLayer id="lay_bd_10_png" name="PNG External WMS"
                      format="png"/>
    </ber:layerArray>
  </ber:rasterBackdropType>
  <ber:binaryRasterBackdropType id="bd_06" name="Monochromatic city map">
    <ber:description>Monochromatic city map</ber:description>
    <ber:layerArray>
      <ber:mainTiledLayer id="lay_bd_06_tif" name="TIFF" format="tiff" />
      <ber:tiledLayer id="lay_bd_06_cit" name="CIT Layer" format="cit" />
    </ber:layerArray>
    <ber:symbology>
      <ber:binaryRasterSymbolizer>
        <ber:foreground>
          <ber:rgbColor>#00FF00</ber:rgbColor>
        </ber:foreground>
        <ber:background>
           <ber:rgbColor>#005500</ber:rgbColor>
           <se:Opacity>0.4</se:Opacity>
        </ber:background>
      </ber:binaryRasterSymbolizer>
    </ber:symbology>
  </ber:binaryRasterBackdropType>
</ber:backdropTypeArray>

Tiled, main tiled layers

The layer is represented by files covering a specified area using the tile structure. Tiles are of various sizes and can overlap. Tiles of a particular layer need not create a continuous coverage. This structure is used always after importing backdrop maps. The raster backdrop type with tiled layers has to have just one main tiled and can contain one or more tiled layers.

Hierarchical layers

The layer is represented by files which cover the particular area in the hierarchy of various details. The structure is very efficient for displaying large amount of raster data. When user works with large area, the rough data (the pyramid top) is displayed. When zooming in, the rough data is replaced by more and more detailed data (the pyramid base). The pyramidal structure is built from original data (main tiled layer) by the LIDS Application Server. The structure has several parameters that define the size of tiles, number of levels and the overall size of hierarchical layer:

tileWidth – width of a single tile in a hierarchy (recommended value is 1024 pixels)
tileHeight – height of a single tile in a hierarchy (recommended value is 1024 pixels)
decreaseRatio – number of subordinate tiles in X axis which is the superior tile generated from (recommended values is 3 or 4)

Plain layers

As a user works, the required areas of plain raster backdrop are generated by LIDS AS on the fly. The plain layer is usually used when WMS data are defined as a project backdrop type.

maxSize – Maximum pixel size of returned image (optional) – parameters width and height.
maxParallelRequests – Maximum number of requests a single client can execute in parallel.

Dynamic symbology

Dynamic symbology is defined in the thematization.xml metadata part. It consists of 2 parts:

visibility based on the scales (optional)
symbology (common for all scales)

Example: Raster backdrop dynamic symbology (part of thematization.xml).

<ber:rasterBackdropStyle id="bts_201" name="Semitransparent raster">
  <ber:rasterSymbolizer>
    <se:Opacity>0.5</se:Opacity>
  </ber:rasterSymbolizer>
</ber:rasterBackdropStyle>
<ber:binaryRasterBackdropStyle id="bts_301" name="Gray foreground">
  <ber:binaryRasterSymbolizer>
    <ber:foreground>
      <ber:rgbColor>#AAAAAA</ber:rgbColor>
    </ber:foreground>
  </ber:binaryRasterSymbolizer>
</ber:binaryRasterBackdropStyle>

Backdrop feature / attributes

It’s possible to define a feature type reference as part of backdrop type definition. In this case, the feature type is used to store additional attributes of individual backdrop files. Features of this type shouldn’t be accessed / edited using standard functionality. They are created / edited / deleted using the mechanism of backdrop maps. When a backdrop file is created, the corresponding feature is generated as well. The GUI for working with the attributes depends on capabilities of individual client applications.

warning

Feature type referenced from the backdrop type definition should define its own history. The feature shouldn’t be stored in the versioned container.

warning

Feature type referenced from the backdrop type definition has to be defined in separate feature types hierarchy. All master feature types of such feature type are considered as backdrop feature types as well and are hidden for the standard functionalities in LIDS clients.

Vector Backdrop Maps​

Dynamic symbology​

Raster Backdrop Maps​

Dynamic symbology​

Backdrop feature / attributes​

Vector Backdrop Maps

Dynamic symbology

Raster Backdrop Maps

Dynamic symbology

Backdrop feature / attributes