set merged particle's xray fieldId as the same with the particle

OTSCPP/OTSImagePro/OTSImageProcess.cpp

@@ -2341,6 +2341,7 @@ namespace OTSIMGPROC
 		xray->SetElementQuantifyData(newCheList);
 		partTagId++;
 		xray->SetIndex(partTagId);
+		xray->SetScanFieldId(p->GetFieldId());
 		newPart->SetXrayInfo(xray);
 		newPart->SetConnectedParticlesSequentialString(partsStr);
 		newPart->SetSubParticles(allSubParts);