rspfDpt rspfLlxyProjection::forward(const rspfGpt &worldPoint) const
{
rspfDpt result;
worldToLineSample(worldPoint, result);
return result;
}
ossimDpt ossimH5GridModel::extrapolate( const ossimGpt& gpt ) const
{
if (traceDebug())
{
ossimNotify(ossimNotifyLevel_DEBUG)
<< "DEBUG ossimH5GridModel::extrapolate: entering... " << std::endl;
}
theExtrapolateGroundFlag = true;
double height = 0.0;
//---
// If ground point supplied has NaN components, return now with a NaN point.
//---
if ( (ossim::isnan(gpt.lat)) || (ossim::isnan(gpt.lon)) )
{
theExtrapolateGroundFlag = false;
if (traceDebug())
{
ossimNotify(ossimNotifyLevel_DEBUG)
<< "DEBUG ossimH5GridModel::extrapolate: returning..." << std::endl;
}
return ossimDpt(ossim::nan(), ossim::nan());
}
if(ossim::isnan(gpt.hgt) == false)
{
height = gpt.hgt;
}
if(theSeedFunction.valid())
{
ossimDpt ipt;
theSeedFunction->worldToLineSample(gpt, ipt);
theExtrapolateGroundFlag = false;
return ipt;
}
//---
// Determine which edge is intersected by the radial, and establish
// intersection:
//---
ossimDpt edgePt (gpt);
ossimDpt image_center (theRefGndPt);
if ( m_crossesDateline )
{
// Longitude points between 0 and 360.
if (edgePt.lon < 0.0 ) edgePt.lon += 360.0;
if ( image_center.lon < 0.0 ) image_center.lon += 360.0;
}
m_boundGndPolygon.clipLineSegment(image_center, edgePt);
//---
// Compute an epsilon perturbation in the direction away from edgePt for
// later computing directional derivative:
//---
const double DEG_PER_MTR = 8.983152841e-06; // Equator WGS-84...
double epsilon = theMeanGSD*DEG_PER_MTR; //degrees (latitude) per pixel
ossimDpt deltaPt (edgePt-image_center);
ossimDpt epsilonPt (deltaPt*epsilon/deltaPt.length());
edgePt -= epsilonPt;
ossimDpt edgePt_prime (edgePt - epsilonPt);
//---
// Establish image point corresponding to edge point and edgePt+epsilon:
//---
ossimGpt edgeGP (edgePt.lat, edgePt.lon, height);//gpt.hgt);
ossimGpt edgeGP_prime (edgePt_prime.lat, edgePt_prime.lon, height);//gpt.hgt);
if ( m_crossesDateline )
{
// Put longitude back between -180 and 180.
edgeGP.limitLonTo180();
edgeGP_prime.limitLonTo180();
}
worldToLineSample(edgeGP, edgePt);
worldToLineSample(edgeGP_prime, edgePt_prime);
//---
// Compute approximate directional derivatives of line and sample along
// radial at the edge:
//---
double dsamp_drad = (edgePt.samp - edgePt_prime.samp)/epsilon;
double dline_drad = (edgePt.line - edgePt_prime.line)/epsilon;
//---
// Now extrapolate to point of interest:
//---
double delta = (ossimDpt(gpt) - ossimDpt(edgeGP)).length();
ossimDpt extrapolated_ip (edgePt.samp + delta*dsamp_drad,
edgePt.line + delta*dline_drad);
if (traceDebug())
{
ossimNotify(ossimNotifyLevel_DEBUG)
<< "DEBUG ossimH5GridModel::extrapolate: returning..." << std::endl;
}
theExtrapolateGroundFlag = false;
return extrapolated_ip;
} // ossimH5GridModel::extrapolate
