GDAL_GCP * PrepareGCP(const CPLString& sFileName, OGRPoint *pt1, OGRPoint *pt2, OGRPoint *pt3, OGRPoint *pt4, OGRPoint *ptCenter, const OGRSpatialReference &oDstOGRSpatialReference, const int nRasterSizeX, const int nRasterSizeY, int &nGCPCount, OGREnvelope &DstEnv)
{
// to meters
double dfFocusM = dfFocus / 100;
double dfFilmHalfHeightM = dfFilmHeight / 200;
double dfRatio = dfFilmHalfHeightM / dfFocusM;
//create center point and line of scene
OGRPoint ptShortSideBeg = GetCenterOfLine(pt1, pt4);
OGRPoint ptShortSideEnd = GetCenterOfLine(pt2, pt3);
OGRLineString lnTmp;
lnTmp.addPoint(&ptShortSideBeg);
lnTmp.addPoint(&ptShortSideEnd);
lnTmp.Value(lnTmp.Project(pt1), &ptShortSideBeg);
lnTmp.Value(lnTmp.Project(pt2), &ptShortSideEnd);
double dfDist1 = pt1->Distance(pt2);
double dfDist2 = pt2->Distance(pt3);
double dfDist3 = pt3->Distance(pt4);
double dfDist4 = pt4->Distance(pt1);
double dfHalfWidth = (dfDist2 + dfDist4) / 4;
double dfHalfHeight = (dfDist1 + dfDist3) / 4;
double dfAltitudeAtSide = (dfHalfWidth * dfFocusM) / dfFilmHalfHeightM;
double dfAltitudeAtSceneCenter = sqrt( dfAltitudeAtSide * dfAltitudeAtSide - dfHalfHeight * dfHalfHeight);
double dfAltitude = dfAltitudeAtSceneCenter * cos(dfMountAngleRad); // 145 - 220 km
double dfDistCenter = dfAltitudeAtSceneCenter * sin(dfMountAngleRad);
OGRLineString lnCenterLeft;
lnCenterLeft.addPoint(&ptShortSideBeg);
lnCenterLeft.addPoint(ptCenter);
OGRPoint ptSatCenter = GetTangetPoint(lnCenterLeft, dfDistCenter);
std::vector<OGRPoint> aPt1, aPt2;
int nTotalGCPCount = ((SEGMENT_STEPS + 1) * 2);
GDAL_GCP *paGSPs = (GDAL_GCP *) CPLMalloc (nTotalGCPCount * sizeof(GDAL_GCP));
GDALInitGCPs(nTotalGCPCount, paGSPs);
double dfImageStepLen = double(nRasterSizeX) / SEGMENT_STEPS;
double dfImageCenterX = 0;
OGRLineString lnCenter;
lnCenter.addPoint(&ptShortSideBeg);
lnCenter.addPoint(ptCenter);
lnCenter.addPoint(&ptShortSideEnd);
double dfCenterLineLen = lnCenter.get_Length();
double dfStepLen = dfCenterLineLen / SEGMENT_STEPS;
double dfCenterLineHalfLen = dfCenterLineLen / 2;
for(double i = 0; i <= dfCenterLineLen; i += dfStepLen)
{
OGRPoint ptTmp;
lnCenter.Value(i, &ptTmp);
double dfDist = fabs(dfCenterLineHalfLen - i);
double dfWidthTmp = GetWidthForHeight(dfAltitudeAtSceneCenter, dfDist, dfRatio);
OGRLineString lnTmpLine;
lnTmpLine.addPoint(ptCenter);
lnTmpLine.addPoint(&ptTmp);
int direction = 1;
if(dfCenterLineHalfLen < i)
direction = -1;
OGRPoint ptUp = GetTangetPoint(lnTmpLine, dfWidthTmp * direction);
OGRPoint ptDown = GetTangetPoint(lnTmpLine, -dfWidthTmp * direction);
//OGRPoint ptUp = GetValue(dfWidthTmp, lnTmpLine);
//OGRPoint ptDown = GetValue(-dfWidthTmp, lnTmpLine);
aPt1.push_back(ptUp);
aPt2.push_back(ptDown);
paGSPs[nGCPCount].dfGCPLine = 0;
paGSPs[nGCPCount].dfGCPPixel = dfImageCenterX;
paGSPs[nGCPCount].dfGCPX = ptDown.getX();
paGSPs[nGCPCount].dfGCPY = ptDown.getY();
paGSPs[nGCPCount].dfGCPZ = dfMeanHeight;
paGSPs[nGCPCount].pszId = CPLStrdup(CPLSPrintf("pt%d", nGCPCount));
nGCPCount++;
paGSPs[nGCPCount].dfGCPLine = nRasterSizeY;
paGSPs[nGCPCount].dfGCPPixel = dfImageCenterX;
paGSPs[nGCPCount].dfGCPX = ptUp.getX();
paGSPs[nGCPCount].dfGCPY = ptUp.getY();
paGSPs[nGCPCount].dfGCPZ = dfMeanHeight;
paGSPs[nGCPCount].pszId = CPLStrdup(CPLSPrintf("pt%d", nGCPCount));
nGCPCount++;
dfImageCenterX += dfImageStepLen;
}
// add points to polygon
OGRLinearRing Ring;
for(int i = 0; i < aPt1.size(); ++i)
Ring.addPoint(aPt1[i].getX(), aPt1[i].getY());
for(int i = aPt2.size() - 1; i >= 0; --i)
Ring.addPoint(aPt2[i].getX(), aPt2[i].getY());
Ring.closeRings();
OGRPolygon Rgn;
Rgn.addRingDirectly((OGRCurve*)Ring.clone());
Rgn.assignSpatialReference(oDstOGRSpatialReference.Clone());
Rgn.flattenTo2D();
Rgn.getEnvelope(&DstEnv);
SaveGeometry(CPLResetExtension(sFileName, "shp"), Rgn, oDstOGRSpatialReference);
return paGSPs;
}
