Hi Don
I have tried integrating the IDV's data transect as suggested by you, but
found it too expensive for the time I have to spend on the project.
So I tried to implement a simple data transect functionality as the
P6_05.java example.
The example is very simple, but I can not understand why I get Nan values
for the transect line that results from the intersection of a flatfield and
a line.
Could you please give me a hint?
Here is my code:
// Displays the transect line on the main display
try {
ConstantMap[] cMaps = { new ConstantMap( 1.0f, Display.Red ),
new ConstantMap( 1.0f, Display.Green ),
new ConstantMap( 1.0f, Display.Blue ),
new ConstantMap( 5.50f,
Display.PointSize ) };
final int numberOfPoints = 1000;
// Line transect
final double initLatitude
currentRangeLat[0]+(currentRangeLat[1]-currentRangeLat[0])/2;
final double initLongitude
currentRangeLon[0]+(currentRangeLon[1]-currentRangeLon[0])/2;
Real cursorCoords;
if (cutLongitude == true) {
cursorCoords = new Real(rt_lon, initLongitude);
}
else {
cursorCoords = new Real(rt_lat, initLatitude);
}
...
// White Point
cursorDataRef = new DataReferenceImpl("cursorDataRef");
cursorDataRef.setData(cursorCoords);
// White Line
wLineDataRef = new DataReferenceImpl("wLineDataRef");
display.addReferences( new DirectManipulationRendererJ3D(),
cursorDataRef, cMaps );
display.addReference(wLineDataRef);
if (cutLongitude == true) {
whiteLine = (Set) makeLongitudeLineSet(initLatitude,
numberOfPoints);
}
else {
whiteLine = (Set) makeLatitudeLineSet(initLongitude,
numberOfPoints);
}
wLineDataRef.setData(whiteLine);
// Transect Line
tLineDataRef = new DataReferenceImpl("tLineDataRef");
ConstantMap[] tLineMaps = { new ConstantMap(2.0f,
Display.PointSize) };
transectDisplay.addReference(tLineDataRef, tLineMaps);
surfsField = (FlatField) baseMap_sequence;
transectLine = (FlatField) surfsField.resample(whiteLine);
tLineDataRef.setData(transectLine);
CellImpl cell = new CellImpl() {
public void doAction() throws RemoteException,
VisADException {
if (cutLongitude == true) {
Real lon = (Real) cursorDataRef.getData();
double lat = initLatitude;
// Make a new line
whiteLine = (Set)
makeLongitudeLineSet(lon.getValue(), numberOfPoints);
}
else {
double lon = initLongitude;
Real lat = (Real) cursorDataRef.getData();
// Make a new line
whiteLine = (Set)
makeLatitudeLineSet(lat.getValue(), numberOfPoints);
}
// Re-set Data, will update display
wLineDataRef.setData(whiteLine);
// Transect Data
surfsField = (FlatField) baseMap_sequence;
int resampMode = Data.NEAREST_NEIGHBOR;
int errorMode = Data.NO_ERRORS;
transectLine = (FlatField)
surfsField.resample(whiteLine, <--------------------------------
resampMode, <- HERE I GET ONLY "NAN" VALUES! |
errorMode); <--------------------------------
tLineDataRef.setData(transectLine);
}
};
cell.addReference(cursorDataRef);
...
}
catch (Exception e) {
...
}
And the make line methods that seem to work correctly:
private Set makeLongitudeLineSet(double northingValue, int pointsPerLine
)
throws VisADException, RemoteException {
// Arbitrary easting end values of the line
double lowVal = currentRangeLat[0];
double hiVal = currentRangeLat[1];
double[][] domainSamples = new double[2][pointsPerLine];
double lonVal = lowVal;
double increment = ( hiVal - lowVal )/ (double) (pointsPerLine-1) ;
for(int i=0;i<pointsPerLine;i++){
domainSamples[0][i] = lonVal;
domainSamples[1][i] = northingValue;
lonVal += increment;
}
RealTupleType domain = new RealTupleType(rt_lon, rt_lat);
return new Gridded2DDoubleSet( domain, domainSamples,
pointsPerLine);
}
private Set makeLatitudeLineSet(double eastingValue, int pointsPerLine )
throws VisADException, RemoteException {
// Arbitrary northing end values of the line
double lowVal = currentRangeLon[0];
double hiVal = currentRangeLon[1];
double[][] domainSamples = new double[2][pointsPerLine];
double latVal = lowVal;
double increment = ( hiVal - lowVal )/ (double) (pointsPerLine-1) ;
for(int i=0;i<pointsPerLine;i++){
domainSamples[0][i] = eastingValue;
domainSamples[1][i] = latVal;
latVal += increment;
}
RealTupleType domain = new RealTupleType(rt_lon, rt_lat);
return new Gridded2DDoubleSet( domain, domainSamples,
pointsPerLine);
}
Thanks
Antonio Benvenuti
-----Messaggio originale-----
Da: Don Murray [mailto:dmurray@xxxxxxxxxxxxxxxx]
Inviato: lunedì 11 settembre 2006 15.55
A: Antonio Benvenuti
Cc: visad@xxxxxxxxxxxxxxxx
Oggetto: Re: Help on Data Transect
Hi Antonio-
Antonio Benvenuti wrote:
> I would like to implement a functionality like IDV's "Data Transect"
> in my application.
> I am actually representing a base map from a netcdf file, mapping
> latitude, longitude respectively on the Y, X axes and the altitude as RGB
values.
> Could you suggest me a way to do it?
The easiest thing would be too look through the
ucar.unidata.idv.control.DataTransectControl and work your way back. But for
a quick summary the IDV has:
3 Data References with RealTuples (XYZ) in them for the selector points (two
end points, one mid point).
1 Data Reference with a Gridded2DSet on a 1D manifold (for the line)
ActionImpls that listen for changes when the selector points are directly
manipulated and update the postions of the line and other points.
A listener on the line so that when it changes:
- A sampling set of points along the line is generated
(see ucar.unidata.data.grid.GridUtil.sliceAlongLatLonLine)
- the data field is resamples along that line.
You could reinvent this all, or just use the pieces of the IDV library that
we've already developed.
Don
*************************************************************
Don Murray UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx P.O. Box 3000
(303) 497-8628 Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
*************************************************************
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