rendererutilities.html

Geotools是一个开源的Java GIS工具包,可利用它来开发符合标准的地理信息系统。Geotools提供了OGC(Open Geospatial Consortium)规范的一个实现来作为他们的

 coordinate space should be used directly without compensating for
 distortions in it with respect to the shape of the real Earth.
 
 NOTE: we are actually doing a a much more exact calculation, and
 accounting for non-square pixels (which are allowed in WMS) ADDITIONAL
 NOTE from simboss: I added soe minor fixes. See below.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>envelope</CODE> - <DD><CODE>coordinateReferenceSystem</CODE> - <DD><CODE>imageWidth</CODE> - <DD><CODE>imageHeight</CODE> - <DD><CODE>DPI</CODE> - screen dots per inch (OGC standard is 90)
<DT><B>Throws:</B>
<DD><CODE>TransformException</CODE>
<DD><CODE>FactoryException</CODE></DL>
</DD>
</DL>
<HR>

<A NAME="calculateOGCScale(org.geotools.geometry.jts.ReferencedEnvelope, int, java.util.Map)"><!-- --></A><H3>
calculateOGCScale</H3>
<PRE>
public static double <B>calculateOGCScale</B>(<A HREF="../../../../org/geotools/geometry/jts/ReferencedEnvelope.html" title="class in org.geotools.geometry.jts">ReferencedEnvelope</A>&nbsp;envelope,
                                       int&nbsp;imageWidth,
                                       <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/util/Map.html" title="class or interface in java.util">Map</A>&nbsp;hints)</PRE>
<DL>
<DD>This method performs the computation using the methods suggested by the OGC SLD specification, page 26.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>envelope</CODE> - <DD><CODE>imageWidth</CODE> - 
<DT><B>Returns:</B><DD></DL>
</DD>
</DL>
<HR>

<A NAME="calculateScale(org.geotools.geometry.jts.ReferencedEnvelope, int, int, java.util.Map)"><!-- --></A><H3>
calculateScale</H3>
<PRE>
public static double <B>calculateScale</B>(<A HREF="../../../../org/geotools/geometry/jts/ReferencedEnvelope.html" title="class in org.geotools.geometry.jts">ReferencedEnvelope</A>&nbsp;envelope,
                                    int&nbsp;imageWidth,
                                    int&nbsp;imageHeight,
                                    <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/util/Map.html" title="class or interface in java.util">Map</A>&nbsp;hints)
                             throws TransformException,
                                    FactoryException</PRE>
<DL>
<DD>First searches the hints for the scale denominator hint otherwise calls 
 <A HREF="../../../../org/geotools/renderer/lite/RendererUtilities.html#calculateScale(com.vividsolutions.jts.geom.Envelope, org.opengis.referencing.crs.CoordinateReferenceSystem, int, int, double)"><CODE>calculateScale(Envelope, CoordinateReferenceSystem, int, int, double)</CODE></A>.  If
 the hints contains a DPI then that DPI is used otherwise 90 is used (the OGS default).
<P>
<DD><DL>

<DT><B>Throws:</B>
<DD><CODE>TransformException</CODE>
<DD><CODE>FactoryException</CODE></DL>
</DD>
</DL>
<HR>

<A NAME="calculateScale(org.geotools.geometry.jts.ReferencedEnvelope, int, int, double)"><!-- --></A><H3>
calculateScale</H3>
<PRE>
public static double <B>calculateScale</B>(<A HREF="../../../../org/geotools/geometry/jts/ReferencedEnvelope.html" title="class in org.geotools.geometry.jts">ReferencedEnvelope</A>&nbsp;envelope,
                                    int&nbsp;imageWidth,
                                    int&nbsp;imageHeight,
                                    double&nbsp;DPI)
                             throws TransformException,
                                    FactoryException</PRE>
<DL>
<DD>Find the scale denominator of the map. Method: 1. find the diagonal
 distance (meters) 2. find the diagonal distance (pixels) 3. find the
 diagonal distance (meters) -- use DPI 4. calculate scale (#1/#2)
 
 NOTE: return the scale denominator not the actual scale (1/scale =
 denominator)
 
 TODO: (SLD spec page 28): Since it is common to integrate the output of
 multiple servers into a single displayed result in the web-mapping
 environment, it is important that different map servers have consistent
 behaviour with respect to processing scales, so that all of the
 independent servers will select or deselect rules at the same scales. To
 insure consistent behaviour, scales relative to coordinate spaces must be
 handled consistently between map servers. For geographic coordinate
 systems, which use angular units, the angular coverage of a map should be
 converted to linear units for computation of scale by using the
 circumference of the Earth at the equator and by assuming perfectly
 square linear units. For linear coordinate systems, the size of the
 coordinate space should be used directly without compensating for
 distortions in it with respect to the shape of the real Earth.
 
 NOTE: we are actually doing a a much more exact calculation, and
 accounting for non-square pixels (which are allowed in WMS) ADDITIONAL
 NOTE from simboss: I added soe minor fixes. See below.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>envelope</CODE> - <DD><CODE>imageWidth</CODE> - <DD><CODE>imageHeight</CODE> - <DD><CODE>DPI</CODE> - screen dots per inch (OGC standard is 90)
 
 
 TODO should I take into account also the destination CRS? Otherwise I am
 just assuming that the final crs is lon,lat that is it maps lon to x (n
 raster space) and lat to y (in raster space).
<DT><B>Throws:</B>
<DD><CODE>TransformException</CODE>
<DD><CODE>FactoryException</CODE></DL>
</DD>
</DL>
<HR>

<A NAME="worldToScreenTransform(com.vividsolutions.jts.geom.Envelope, java.awt.Rectangle, org.opengis.referencing.crs.CoordinateReferenceSystem)"><!-- --></A><H3>
worldToScreenTransform</H3>
<PRE>
public static <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/geom/AffineTransform.html" title="class or interface in java.awt.geom">AffineTransform</A> <B>worldToScreenTransform</B>(<A HREF="http://www.jump-project.org/docs/jts/1.7/api/com/vividsolutions/jts/geom/Envelope.html" title="class or interface in com.vividsolutions.jts.geom">Envelope</A>&nbsp;mapExtent,
                                                     <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/Rectangle.html" title="class or interface in java.awt">Rectangle</A>&nbsp;paintArea,
                                                     CoordinateReferenceSystem&nbsp;destinationCrs)</PRE>
<DL>
<DD>This worldToScreenTransform method makes the assumption that the crs is
 in Lon,Lat or Lat,Lon. If the provided envelope does not carry along a
 crs the assumption that the map extent is in the classic Lon,Lat form. In
 case the provided envelope is of type.
 
 Note that this method takes into account also the OGC standard with
 respect to the relation between pixels and sample.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>mapExtent</CODE> - The envelope of the map in lon,lat<DD><CODE>paintArea</CODE> - The area to paint as a rectangle<DD><CODE>destinationCrs</CODE> - </DL>
</DD>
</DL>
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