Celestial Navigation Plugin Redux

[Taarnskov]

When plotting three stars from textbook i get pretty close to the result, but the plugin do not remember the index error. I don't think that the plugin use the index error in the calculation.

Lars

[seandepagnier]

It maybe doesn't remember index error from each run, but should work. Did you check the computations tab?

[Taarnskov]

I don't think it uses the index error correction because under the tab calculation it is set to 0. I have entered all data and pushed the OK button, and after that edited the sight.

I can make it work if i change the eye height after changing the index error.

[seandepagnier]

ok this is a slight bug and will be corrected. Thank you.

[Taarnskov]

It would be nice to be able to make a way point from the celestial fix with a push of a button. The way point should include the information from the calculation tab from all the sights included in the fix. There is room below the information button.

The fix should also be transferred to the logbook from Konni if possible.

[HappySeagull]

I 've been wondering....... is there going to be a way to "advance" an LOP? ...IE: I'm pretty rusty on this but back in the day, in cloudy weather, I'd get sights when I could, and then advance them per my DR to intersect my next possible sight...it was also pretty common method to get a morning sun sight and then advance it to the noon sight...or vice versa to an afternoon or star shot
Practically, there's often no way to get two or three sights simultaneously and a couple of sailing miles will elapse at least... do you see what I mean?
That said, I think I can do this with O's route maker albeit it's clumsy (drawing DR from LOP through AP and then two sides of the advanced lop from it=three lines...?)

[HappySeagull]

..I found a quote from Navigation in a Teacup that explains what I mean:

"Running Fix 
The running fix is a method by which two or more line of positions (LOPs) 
taken at different times on a moving vessel can be coalesced together to 
represent a navigational fix at any single arbitrary time between the 
observations.  Most frequently, it is used to advance an old LOP to get a fix 
with a new LOP while the ship is under way.  Quite simply, the old LOP is 
parallel-advanced in the direction of the true course-made-good (TC) to the 
DR distance between the last LOP and the new one.  With a quick study of the 
figure, the reader should discern the mechanics involved.  Essentially, if you 
produced a ‘good’ LOP earlier, you can ‘drag it’ along with your moving vessel 
as if it were pinned to the stern using the simple distance = rate x time for the 
distance to drag, and it gets dragged in the same course direction as the vessel. "

[seandepagnier]

Yes you can, I support it. You must enter DR bearing and distance, and it shifts the sight by that much. So if you take a sight in the morning, you can say you traveled 30 miles, take another sun sight, and get a position

The position has to be determined visually by looking where the sights overlap on the chart. (the red X won't work for this)

It can not compute a fix from sights shifted in this manner because the resulting shifted positions are no longer a circle on the earth. For example, if you shift north 1000 miles, and parts of the sight are nearer to the pole than 1000 miles, then they cross over, and you have a figure 8. This is an obvious case, but it turns out, you never have a circle anymore unless you shift exactly east or west. Therefore the position you are on is no longer described by a plane or sphere or cone or whateveer intersecting the earth. If you can derive an equation which does describe something which intersects the earth at all the possible positions once shifted by a bearing and distance, I would love to hear about it as I could then determine fixes. In the meantime, just do it visually.

[HappySeagull]

Aha! I see it now! On the config tab! Thanks! I couldn't ask for more.

[rgleason]

Sean, is there another version to git clone that fixes the fix replaces fix repllaces fix bug? Or have you been busy with other things? Thanks

[seandepagnier]

Originally Posted by rgleason

Sean, is there another version to git clone that fixes the fix replaces fix repllaces fix bug? Or have you been busy with other things? Thanks

No, I cannot reproduce it, and as far as I know you are the only person who has this. I really would like to see it fixed though.

[cagney]

Originally Posted by boat_alexandra

....
....
If you can derive an equation which does describe something which intersects the earth at all the possible positions once shifted by a bearing and distance, I would love to hear about it as I could then determine fixes. In the meantime, just do it visually.

In my mind, this is just a case of moving the geographical position of the body (dec,LHA), equal to the center of the position circle, with the bearing and distance, and then redraw the position circle. Regard it as a new body if you like.

Thomas

[rgleason]

I deleted the plugin and git clone and recompiled:
It still breaks immediately after the second fix is entered, line 159 and 508 in celestial_navigation_pi.dll

wxmsw28ud_core_vc_custom.dll!wxListCtrl::InsertItem(const wxListItem & info)  Line 1625 + 0x1a bytes    C++
 
 celestial_navigation_pi.dll!CelestialNavigationDialog::UpdateSights()  Line 149 + 0x15 bytes    C++
     celestial_navigation_pi.dll!CelestialNavigationDialog::OnNew(wxCommandEvent & event)  Line 508    C++
     wxbase28ud_vc_custom.dll!wxAppConsole::HandleEvent(wxEvtHandler * handler, void (wxEvent &)* func, wxEvent & event)  Line 323    C++
     wxbase28ud_vc_custom.dll!wxEvtHandler::ProcessEventIfMatches(const wxEventTableEntryBase & entry, wxEvtHandler * handler, wxEvent & event)  Line 1241    C++

CelestialNavigationDialogue.cpp Update Sights Line 149

    // then add sights to the listctrl
    SightList::iterator it;
    wxListItem item;
    int index = 0;

    for (it = m_SightList.begin(); it != m_SightList.end(); ++it, ++index)
    {
        item.SetId(index);
        item.SetImage((*it)->IsVisible() ? 0 : -1);
        item.SetData(index);
        
        long idx = m_lSights->InsertItem(item);
        m_lSights->SetItemImage(index, (*it)->IsVisible() ? 0 : -1);
        m_lSights->SetItem(idx, rmTYPE, (*it)->m_Type ? _("Azimuth") : _("Altitude"));
        m_lSights->SetItem(idx, rmBODY, (*it)->m_Body);
        m_lSights->SetItem(idx, rmTIME, (*it)->m_DateTime.Format());
        m_lSights->SetItem(idx, rmMEASUREMENT, wxString::Format(_T("%.4f"), (*it)->m_Measurement));
        
        m_lSights->SetItem(idx, rmCOLOR,
                           wxString::Format(_T("0x%hhx%hhx%hhx"),
                                            (*it)->m_Colour.Red(),
                                              (*it)->m_Colour.Green(),   <--Line 149
                                            (*it)->m_Colour.Blue()));
    }

CelestialNavigationDialogue.cpp On new command event Line 508

void CelestialNavigationDialog::OnNew(wxCommandEvent &event)
{
    wxDateTime now = wxDateTime::Now();
    now.MakeUTC();

    Sight s(Sight::ALTITUDE, _("Sun"), Sight::LOWER, now, 1, 0, .25);
    SightDialog dialog(GetParent(), s);
      
    if( dialog.ShowModal() == wxID_OK ) {
        Sight *ns = new Sight(s);

        dialog.RecomputeSight();
        ns->RebuildPolygons();
        m_SightList.Append(ns);
        UpdateSights();
        RequestRefresh( GetParent() );    <---Line 508
    }
}

Don't know how to fix it. In Debug version it won't "Continue" so I have to "Stop Debugging"

I've done this 3 times with the same results each time.

[HappySeagull]

Originally Posted by cagney

In my mind, this is just a case of moving the geographical position of the body (dec,LHA), equal to the center of the position circle, with the bearing and distance, and then redraw the position circle. Regard it as a new body if you like.

Thomas

good idea, Thomas!
boat_alexandra, another question: the "degrees certainty"...what is your thinking per the .25 default?

[cagney]

Originally Posted by cagney

In my mind, this is just a case of moving the geographical position of the body (dec,LHA), equal to the center of the position circle, with the bearing and distance, and then redraw the position circle. Regard it as a new body if you like.

Thomas

I better correct myself. Read GHA instead of LHA above.
Thomas