Ari,
You should create Polygons to represent your complex shapes and LineStrings
to represent your access paths (both Polygon and LineString are Geometries -
then you can call the convertWGS84ToUTM method passing them as argument),
check the javadoc api to see how you can create them:
http://tsusiatsoftware.net/jts/javadoc/index.html
I never tried drawing the geometries myself, but are you sure you need to
convert them to UTM to do so? Discussions about drawing geometries bounced
around the list (not sure in what type of canvas thought), but if you search
around you could find valuable information.
Regards,
Alexandre Pretyman
On Wed, Jan 14, 2009 at 6:02 PM, ari fainchtein <[email protected]> wrote:
> A,Thanks for the info. Now that I discovered the JTS I guess I have
> another question. My original idea was to walk around my farm with a gps
> unit, take points on the corner of a building, put them in my software
> convert them to UTM and then plot them on a canvas. This is so that I can
> do this all over my farm mapping greenhouses, vegetables fields and every
> fruit tree. Since some will be square (ie buildings) and some will be
> circles (ie trees) and some will not be defined shapes ( access paths) is my
> approach still valid? Do you have abetter way to create a map of all the
> objects in my farm using JTS?
>
> Also in the code you gave you say:
>
> Call convertToUTM() on your Geometries to convert them accordingly.
>
>
> so if i have 4 sets of gps coordinates representing the corners of a
> building, how should I call convertToUTM?
>
> thanks so much for the help
>
>
> On 14/01/2009, at 5:34 AM, Alexandre Pretyman wrote:
>
> Ari,
>
> Geometry is a class from the popular Java Topology Suite (JTS) -
> jts-1.10.jar (
> http://docs.codehaus.org/display/GEOTDOC/03+JTS+Topology+Suite ),
> NoSuchAuthorityCodeException and FactoryException is from the geoapi jar
> (I use geoapi-2.2-M1.jar), CRS is from the referencing jar (I use
> gt-referencing-2.5-RC1.jar). The imports are these:
>
> import org.apache.log4j.Logger;
> import org.geotools.factory.Hints;
> import org.geotools.geometry.jts.JTS;
> import org.geotools.referencing.CRS;
> import org.opengis.geometry.MismatchedDimensionException;
> import org.opengis.referencing.FactoryException;
> import org.opengis.referencing.NoSuchAuthorityCodeException;
> import org.opengis.referencing.crs.CRSAuthorityFactory;
> import org.opengis.referencing.crs.CoordinateReferenceSystem;
> import org.opengis.referencing.operation.MathTransform;
> import org.opengis.referencing.operation.TransformException;
>
> import com.vividsolutions.jts.geom.Coordinate;
> import com.vividsolutions.jts.geom.Geometry;
> import com.vividsolutions.jts.geom.GeometryFactory;
> import com.vividsolutions.jts.geom.Point;
> import com.vividsolutions.jts.geom.PrecisionModel;
> import com.vividsolutions.jts.geom.impl.CoordinateArraySequence;
> import com.vividsolutions.jts.linearref.LinearLocation;
> import com.vividsolutions.jts.linearref.LocationIndexedLine;
>
> you will need the epsg-hsql-2.5-SNAPSHOT.jar and probably the
> gt-api-2.5-RC1.jar, gt-main-2.5-RC1.jar, gt-metadata-2.5-RC1.jar. I'm not
> sure these are the latest versions available for the respetive jars, but it
> is what maven downloaded for me with the following pom dependencies (you
> will know what the pom dependencies are if you follow the first project
> tutorial at the wiki:
> http://docs.codehaus.org/display/GEOTDOC/03+First+Project )
>
> <dependency>
> <groupId>org.geotools</groupId>
> <artifactId>gt-main</artifactId>
> <version>2.5-RC1</version>
> </dependency>
> <dependency>
> <groupId>org.geotools</groupId>
> <artifactId>epsg-hsql</artifactId>
> <version>2.5-SNAPSHOT</version>
> </dependency>
>
> If anyone sees that these versions are incorrect, please shout out (-:
>
> Regards,
> Alexandre Pretyman
>
>
> On Mon, Jan 12, 2009 at 8:09 PM, ari fainchtein <[email protected]>wrote:
>
>> A,Thanks for the code. What version are you running? I am using 2.5.1
>> and objects like Geometry, NoSuchAuthorityCodeException, FactoryException,
>> etc don't seem to be part of it. I tried looking in the javadoc and those
>> objects dont seem to be there either. Could you send me your package
>> statements?
>>
>> thanks
>>
>> On 13/01/2009, at 3:23 AM, Alexandre Pretyman wrote:
>>
>> Hi Ari,
>> Try the following code and see if it suffice your needs, it is what I
>> wrote to convert from WGS84 to UTM, I'm not sure this is the best method,
>> but has been working for me so far.
>>
>> =============================
>>
>> /**
>> * Conversion utility class to convert from WGS84 to UTM
>> * @author Alexandre Walter Pretyman
>> */
>>
>> public class ConversionUtil
>> {
>> private static final Map<Integer, MathTransform> transformMap = new
>> HashMap<Integer, MathTransform>();
>>
>> private static Logger logger =
>> Logger.getLogger(ConversionUtil.class);
>> public static Geometry convertWGS84ToUTM(Geometry geom)
>> {
>>
>> if (geom.getSRID() != 4326)
>> throw new RuntimeException("Geometry's SRID is not 4326 (WGS84),
>> Geometry: " + geom);
>>
>> int utmzone = utmzone(geom.getCoordinate());
>> final Integer utmZoneInteger = new Integer(utmzone);
>>
>> try
>> {
>> synchronized (transformMap)
>> {
>> MathTransform transform = transformMap.get(utmZoneInteger);
>> if (transform == null)
>> {
>> CoordinateReferenceSystem targetCRS = CRS.decode("EPSG:" + utmzone);
>> transform = CRS.findMathTransform(wgs84CRS, targetCRS);
>> transformMap.put(utmZoneInteger, transform);
>> }
>> final Geometry transformedGeom = JTS.transform(geom, transform);
>> transformedGeom.setSRID(utmzone);
>> return transformedGeom;
>> }
>> }
>> catch (NoSuchAuthorityCodeException e)
>> {
>> logger.error(e.getMessage(), e);
>> throw new RuntimeException(e);
>> }
>> catch (FactoryException e)
>> {
>> logger.error(e.getMessage(), e);
>> throw new RuntimeException(e);
>> }
>> catch (MismatchedDimensionException e)
>> {
>> logger.error(e.getMessage(), e);
>> throw new RuntimeException(e);
>> }
>> catch (TransformException e)
>> {
>> logger.error(e.getMessage(), e);
>> throw new RuntimeException(e);
>> }
>> }
>>
>> /**
>> * Returns the EPSG id for the UTM zone of the given coordinate, this is
>> ported from the code
>> * http://wiki.postgis.org/support/wiki/index.php?plpgsqlfunctions
>> * @param coord
>> * @return
>> */
>> public static int utmzone(Coordinate coord)
>> {
>> int pref;
>> if (coord.y > 0)
>> {
>> pref = 32600;
>> }
>> else
>> {
>> pref = 32700;
>> }
>> final int zone = (int) Math.floor((coord.x+180)/6)+1;
>> return zone + pref;
>> }
>> static CoordinateReferenceSystem wgs84CRS;
>> static CRSAuthorityFactory factory;
>> static {
>>
>> try
>> {
>> Hints hints = new
>> Hints(Hints.FORCE_LONGITUDE_FIRST_AXIS_ORDER, Boolean.TRUE);
>> factory = CRS.getAuthorityFactory(true);
>> wgs84CRS = factory.createCoordinateReferenceSystem("EPSG:4326");
>> }
>> catch (NoSuchAuthorityCodeException e)
>> {
>> logger.error(e.getMessage(), e);
>> throw new RuntimeException(e);
>> }
>> catch (FactoryException e)
>> {
>> logger.error(e.getMessage(), e);
>> throw new RuntimeException(e);
>> }
>> }
>> }
>>
>> =============================
>>
>> Call convertToUTM() on your Geometries to convert them accordingly.
>> There is a problem with this method though, the GeometryFactory of the
>> Geometries created by JTS.transform(geom, transform); have the SRID set to
>> 0, so even I explicitly set them with transformedGeom.setSRID(utmzone);
>> spatial function called on the geometry (for example, buffer), generate
>> other geometries with SRID set to 0, but this is something I have not yet
>> managed to find a solution for.
>>
>> Regards,
>> Alexandre Pretyman
>>
>> On Mon, Jan 12, 2009 at 11:38 AM, Martin Desruisseaux <
>> [email protected]> wrote:
>>
>>> ari fainchtein a écrit :
>>> > Exception in thread "main" java.lang.IncompatibleClassChangeError:
>>> > Implementing class
>>>
>>> Exception ending in "Error" are usually a compilation problem. In this
>>> case, we
>>> lack information about the cause of this error - I don't know what is
>>> happening.
>>> But if you happen to have a chance to recompile GeoTools on your platform
>>> (Mac
>>> OS), it may be worth. If you have the source code and Maven installed,
>>> you only
>>> need to execute "mvn install" from the command-line at the root of source
>>> directory.
>>>
>>> Martin
>>>
>>>
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>>
>>
>>
>
>
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