Matlab STK connection: How to access available existing objects?

Dear all,

I am trying to command STK from Matlab. Connection is running well, but now I am seeking for how I access objects in an existing STK scneario. Everything I found in the internet is how to create a new object.

%%Open STK and Scenario
STK.app = actxserver('STK11.application');
STK.root = STK.app.Personality2;

checkempty = STK.root.Children.Count;
if checkempty == 0
    %If a Scenario is not open, create a new scenario
    STK.app.visible = 1;
else
    %If a Scenario is open, prompt the user to accept closing it or not
    rtn = questdlg({'Close the current scenario?',' ','(WARNING: If you have not saved your progress will be lost)'});
    if ~strcmp(rtn,'Yes')
        return
    else
        STK.root.CurrentScenario.Unload
        STK.app.visible = 1;
    end
end

%%Get current working folder path
currentFolder = pwd;
%Define STK scenario name (already existing scenario)
STK.scenario.name = append(pwd,'\Test_Mission\Test_Mission.sc');
%Load STK scenario (must be located in the working path)
scenario = STK.root.LoadScenario(STK.scenario.name);

%%Extract scenario data
% Here I want to get information of a ground station and later also a
% satellite in order to calculate e.g. access
Redu_Station = STK.root.GetObjectFromPath('.\Test_Mission\Redu_Station.f');
%...

%%Leave STK scenario and instance
%Close the scenario
STK.root.CloseScenario;
%Close STK instance
STK.app.Quit;

The error message is:

Check for missing argument or incorrect argument data type in call to function 'GetObjectFromPath'.

Unfortunately I do not find any description for the different funcions and how to use them.

Also those pageas are not helpful: https://help.agi.com/stkdevkit/11.4.0/Content/stkObjects/ObjModMatlabCodeSamples.htm#1

Please help me!

Christina

[Christina Jetzschmann]

Okay, I found one solution where you need to know, which objects are existing. The GetObjectFromPath command was correct, but used in a wrong way.

You must create a handler to the object:

handler.Redu_Station = STK.root.GetObjectFromPath('/Facility/Redu_Station');

where it is important that the path points to the current working directory. Facility here is not a folder, it is the type of the object you want to access.

If you want to access a satellite, you need to write something like

handler.MySat = STK.root.GetObjectFromPath('/Satellite/MySat');

After creating that handler you can access the object by simply using

MySat.SPA.bound_radius    = 3; % [m]
MySat.EPS.PanelGroupName  = 'Panels'; % defined in the spacecraft model for STK

CmdString                       = ['VO */Satellite/MySat SolarPanel ' ...
                                    'Visualization Radius On ', num2str(MySat.SPA.bound_radius),...
                                    ' AddGroup ',MySat.EPS.PanelGroupName]
STK.root.ExecuteCommand(CmdString);

I hope this helps.

[Shreya Kandagal]

Thank you so much.

[LUCA SEVERIN]

Hi,

I am using your code to load an existing scenrio bu it keeps saying that "One or more output arguments not assigned during call to "LoadScenario". " I can't find the problem

[Christina Jetzschmann]

Can you share your code?

[LUCA SEVERIN]

Yes, it's identical to yours.

The error occurs when it calls the LoadScenario function.

STK.app = actxserver('STK12.application')
STK.root =STK.app.Personality2;

checkempty = STK.root.Children.Count;
if checkempty == 0
    STK.app.visible = 1;
else
    rtn = questdlg({'Close the current scenario?',' ','(WARNING: If you have not saved your progress will be lost)'});
    if ~strcmp(rtn,'Yes')
        return
    else
        STK.root.CurrentScenario.Unload
        STK.app.visible = 1;
    end
end

currentFolder = pwd;
STK.scenario.name = append(pwd,'\QuantumShip\QuantumShip.sc');
scenario = STK.root.LoadScenario(STK.scenario.name);

lat = 0 + (60-0).*rand(10,1);
long = -90 + (0+90).*rand(10,1);
coord = [lat,long]

f = cell(length(coord), 1);
for i = 1 : length(coord)
    f{i} = strcat('Target', num2str(i));
    facility(i) = root.CurrentScenario.Children.New('eTarget', f{i});
    facility(i).Position.AssignGeodetic(coord(i,1),coord(i,2),0)
    facility(i).UseTerrain = true;
end

[Christina Jetzschmann]

maybe you check the relative path...could be the problem

[LUCA SEVERIN]

Yes I checked, I really don't understand. I fear that it is a problem of the new STK version.

[Christina Jetzschmann]

I am sorry. Maybe you check the STK direct support.

Which STK version do you have? Have you adapted the line

STK.app = actxserver('STK11.application');

to the correct version?

[LUCA SEVERIN]

Yes, I did.

Thanks anyway

[Mohamed Dewedar]

In LoadScenario Method documentation : https://help.agi.com/stkdevkit/Content/DocX/STKObjects~IAgStkObjectRoot~LoadScenario.html

It appears that it has a return type "Void" and you can't assign void to the vaiable "scenario". So use:

 STK.root.LoadScenario(STK.scenario.name);

without output variable.

You can refer to the senario object afterwards using:

scenario = STK.root.CurrentScenario;

[Troy McClure]

Ever find the answer to this? I'm having the same issue. The docs don't explain how to build the path.

[Christina Jetzschmann]

See answer below...

Answer 1

[Christina Jetzschmann]

For me, this solution is now working:

%% Open STK and Scenario
STK.app = actxserver('STK11.application');
STK.root = STK.app.Personality2;

checkempty = STK.root.Children.Count;
if checkempty == 0
    % If a Scenario is not open, create a new scenario
    STK.app.visible = 1;
else
    % If a Scenario is open, prompt the user to accept closing it or not
    rtn = questdlg({'Close the current scenario?',' ','(WARNING: If you have not saved your progress will be lost)'});
    if ~strcmp(rtn,'Yes')
        return
    else
        STK.root.CurrentScenario.Unload
        STK.app.visible = 1;
    end
end

%% Get current working folder path
currentFolder       = pwd;
% Define STK scenario name (already existing scenario)
STK.scenario.name   = append(pwd,'\Test_Mission\Test_Mission.sc');
% Load STK scenario (must be located in the working path)
scenario            = STK.root.LoadScenario(STK.scenario.name);

%% Create handler
% Create handler for spacecraft by using path
handler.MySat       = STK.root.GetObjectFromPath('/Satellite/MySat');

% Create handler for facility by using path
handler.Redu_Station= STK.root.GetObjectFromPath('/Facility/Redu_Station');

% Create handler for sensor on spacecraft by using path
handler.MySat_Sensor= STK.root.GetObjectFromPath('/Satellite/MySat/Sensor/Sensor1');

%% Define overall stepsize in [s]
stepsize            = 60;

%% Create access
% Define ground station and spacecraft of interest for access calculations.
facility                            = handler.Redu_Station;
spacecraft                          = handler.MySat;
sensor                              = handler.MySat_Sensor;
access_name                         = 'Redu_Station2MySat_access';

% Call access function (incl. intervals, statistics and AER)
Redu_Station2MySat_access           = STKaccess(facility, spacecraft,scenario,stepsize);
Redu_Station2Sensor1_access         = STKaccess(facility, sensor,scenario,stepsize);

% ...

%% Leave STK scenario and instance
% Close the scenario
STK.root.CloseScenario;
% Close STK instance
STK.app.Quit;

Answer 2

[john]

The way I got valid path names for GetObjectFromPath was:

STK.root.AllInstanceNamesToXML

and it prints all the available objects in the scenario.