How to ensure that all values are not equal when using the ecef2enu function

I'm doing coordinate system transformation using the ecef2enu function. But for some reason, all three E, N, and U values are the same. I wonder why. How can I modify it to get the exact value?

Isn't it normal for the 1, 2, 3 matrices to have different values? Is there something wrong with my code?

currTime = gnss.SensorModel.InitialTime;
setup(scene)
wgs84 = wgs84Ellipsoid('meter');
while scene.IsRunning
    
    [~,~,p,satPos,status] = gnss.read ();
    allSatPos = gnssconstellation(currTime); % ecef
    currTime = currTime + seconds(1/scene.UpdateRate);
    
    [~,trueRecPos] = plat.read; % lla
    trueRecPos_ecef = lla2ecef(trueRecPos); % uav ecef
    [az,el] = lookangles(trueRecPos,satPos,gnss.SensorModel.MaskAngle);
    nsat = length(satPos(:,1));
    enu_sat = zeros(nsat,3);
    for k = 1:1:nsat
        enu_sat(k,:) = ecef2enu(satPos(k,1),satPos(k,2),satPos(k,3),trueRecPos(1),trueRecPos(2),trueRecPos(3),wgs84);
    end
    temp=1;
    unit_sat = normalize(enu_sat,'norm',1);
    target_z = 500;
    scale_factors = target_z ./ unit_sat(:,3);
    unit_sat_scaled = unit_sat .* scale_factors;
end

Answer 1

[Ryan Salvo]

The ecef2enu function returns three output arguments, but you are setting all three columns of the enu_sat variable with only the first output argument. Update the for-loop to:

for k = 1:1:nsat
    [enu_sat(k,1),enu_sat(k,2),enu_sat(k,3)] = ecef2enu(satPos(k,1),satPos(k,2),satPos(k,3),trueRecPos_lla(1),trueRecPos_lla(2),trueRecPos_lla(3),wgs84);
end

[inhyeok]

thanks you!!

Answer 2

[KALYAN ACHARJYA]

As there may be multiple reasons, I don't have the complete data file and am unable to reproduce the issue. Please give it a try converting Earth-Centered Earth-Fixed (ECEF) coordinates to geodetic coordinates first might help.

ecef2lla

trueRecPos_lla = ecef2lla(trueRecPos_ecef);
enu_sat(k,:) = ecef2enu(satPos(k,1), satPos(k,2), satPos(k,3), trueRecPos_lla(1), trueRecPos_lla(2), trueRecPos_lla(3), wgs84);

[inhyeok]

It's the same as before..

I'll show you the full code. I recommend replacing the .osm file in the middle with something else.

referenceLocation=[37.498759 127.027487 0];
stopTime = 1;
scene = uavScenario(ReferenceLocation=referenceLocation,UpdateRate=10,StopTime=stopTime);
xTerrainLimits = [-200 200];
yTerrainLimits = [-200 200];

xBuildingLimits = [-150 150];
yBuildingLimits = [-150 150];
color = [0.80302 0.80298 0.8029];

addMesh(scene,"buildings",{"gangnam_11exit.osm" xBuildingLimits yBuildingLimits,"auto"},color)

uavTrajectory = waypointTrajectory([0 0 1; 0 0 1],TimeOfArrival=[0 stopTime],ReferenceFrame="ENU");

plat = uavPlatform("UAV",scene,Trajectory=uavTrajectory,ReferenceFrame="ENU");
updateMesh(plat,"quadrotor",{1},[1 0 0],eye(4));

gnss = uavSensor("GNSS",plat,gnssMeasurementGenerator(ReferenceLocation=referenceLocation));

fig = figure;
ax = show3D(scene);
uavPosition = uavTrajectory.lookupPose(linspace(0,stopTime,35));
hold on
uavTrajectoryLine = plot3(uavPosition(:,1),uavPosition(:,2),uavPosition(:,3),".",LineWidth=1.5,Color="cyan",MarkerSize=15);
legend(uavTrajectoryLine,"Trajectory",Location="northeast")

clf(fig,"reset")
set(fig,Position=[400 458 1120 420])

hScenePlot = uipanel(fig,Position=[0 0 0.5 1]);
ax = axes(hScenePlot);
[~,pltFrames] = show3D(scene,Parent=ax);
hold(ax,"on")
uavMarker = plot(pltFrames.UAV.BodyFrame,0,0,Marker="o",MarkerFaceColor="cyan");
uavTrajectoryLine = plot3(uavPosition(:,1),uavPosition(:,2),uavPosition(:,3),"--",LineWidth=1.5,Color="cyan");
legend(ax,[uavMarker uavTrajectoryLine],["UAV","Trajectory"],Location="northeast")
view(ax,[0 90])
axis(ax,"equal")
hold(ax,"off")

currTime = gnss.SensorModel.InitialTime;
setup(scene)
wgs84 = wgs84Ellipsoid('meter');
while scene.IsRunning
    
    [~,~,p,satPos,status] = gnss.read ();
    allSatPos = gnssconstellation(currTime); % ecef
    currTime = currTime + seconds(1/scene.UpdateRate);
    
    [~,trueRecPos] = plat.read; % lla
    trueRecPos_ecef = lla2ecef(trueRecPos); % uav ecef
    trueRecPos_lla = ecef2lla(trueRecPos_ecef);
    [az,el] = lookangles(trueRecPos,satPos,gnss.SensorModel.MaskAngle);
    nsat = length(satPos(:,1));
    enu_sat = zeros(nsat,3);
    for k = 1:1:nsat
        enu_sat(k,:) = ecef2enu(satPos(k,1),satPos(k,2),satPos(k,3),trueRecPos_lla(1),trueRecPos_lla(2),trueRecPos_lla(3),wgs84);
    end
    temp=1;
    unit_sat = normalize(enu_sat,'norm',1);
    target_z = 500;
    scale_factors = target_z ./ unit_sat(:,3);
    unit_sat_scaled = unit_sat .* scale_factors;
end