How can I get Matlab to display a warning when one of the temperatures is greater than 2x the other?

The code below opens an infra-red (.SEQ) file and plots the temperature at a point for each frame. I was wondering how I could get Matlab to display a warning when tempInsulator is more than twice as much as the tempAmbient. It would also be nice to plot both temperatures on the same graph. Thanks.

%##### Load image #####
videoFileName='file';
% Load the Atlas SDK
atPath = getenv('FLIR_Atlas_MATLAB');
atImage = strcat(atPath,'Flir.Atlas.Image.dll');
asmInfo = NET.addAssembly(atImage);
%open the IR-file
file = Flir.Atlas.Image.ThermalImageFile(videoFileName);
seq = file.ThermalSequencePlayer();
%Get the pixels
img = seq.ThermalImage.ImageProcessing.GetPixelsArray;
im = double(img);
figure(1)
imshow(im,[])
figure(2)
  %get the temperature of the insulator
  h = plot(1:1:seq.Count,seq.ThermalImage.GetValueFromSignal(im(165,143)));
  title('Temp (C) of the Insulator') 
  ylabel('Temperature (C)')
  xlabel('Frame')
if(seq.Count > 1)
  %pre allocate
  tempAmbient = NaN * ones(seq.Count,1);
  tempInsulator = NaN * ones(seq.Count,1);
  while(seq.Next())
      img = seq.ThermalImage.ImageProcessing.GetPixelsArray;
      im = double(img);
      %get the erature of the insulator and background
      tempAmbient(seq.SelectedIndex) = seq.ThermalImage.GetValueFromSignal(im(165,100));
      tempInsulator(seq.SelectedIndex) = seq.ThermalImage.GetValueFromSignal(im(165,143));
      %plot temp vs frames 
      set(h,'XData',1:1:seq.Count)
      set(h,'YData',tempInsulator)
      figure(1)
      imshow(im,[]);
      drawnow;
  end
  figure(3)
  %temp vs time plot
  count1 = timeseries(tempInsulator(:,1),[0:(double(1)/double(seq.FrameRate)):(double(seq.Count)/double(seq.FrameRate) - 1/double(seq.FrameRate))]);
  count1.Name = ' Temp (C) of the Insulator';
  count1.TimeInfo.Units = 'Sec';
  plot(count1,':b')
end

Answer 1

[Eric]

It depends how you would like it to display. Check out the documentation for warning(), warndlg(), etc. If you want to display the warning on the graph, that will involve text objects and that sort of thing.

To plot on the same graph, use 'hold on' after the first call to plot() or else plot them all in the same call, e.g. plot(x1,y1,x2,y2,...).

[Nathan B]

If I could simply display a message using disp() that'd be great but I want it to display inside the while loop, when putting an if inside the while loop it doesn't seem to work I even tried "if tempAmbient == tempAmbient" and the contents of the if didn't run.

Also I would like to plot both the temperatures in the while loop frame-by-frame plot where there is no plot().

[Eric]

It's hard to debug without the files you are looking at. However, the contents of an 'if' should run when true, unless the while loop is never entered in the first place. Try adding a disp() to the while loop and not in an if statement to see if the loop runs even once. The other issue could be that all your temperatures are NaN, in which case a statement like tempAmbient==tempAmbient is always false, and may be why graphs are not showing up, if you are seeing that too. I should also mention that since tempAmbient is a vector, you will need to index into it for each loop.

[Nathan B]

Thanks I managed to get the message to display by putting x = 0; before the while loop and the if statement below inside it. Any ideas on how I could display both temperatures on the graph whose axis are defined by the two set commands (inside the while loop)?

if tempInsulator(x) > 2*tempAmbient(x)

disp('Warning: Insulator temperature high')

end

x = x + 1;

[Eric]

Basically, you need two line objects from the start. One way to do this is in the line where you define h, change it to

 h(1) = plot(1:1:seq.Count,seq.ThermalImage.GetValueFromSignal(im(165,143)));
 hold on;
 h(2) = plot(1:1:seq.Count,seq.ThermalImage.GetValueFromSignal(im(165,143)));

There are several ways to achieve this, e.g. it can also be done with repmat() and a single call to plot. Now you will have two lines and can update them as such:

 set(h(1),'YData',tempInsulator)
 set(h(2),'YData',tempAmbient)

Also, if seq.Count never changes, you don't need to update it.

[Nathan B]

I'm getting an error:

In an assignment A(:) = B, the number of elements in A and B must be the same.

Error in SeqDemoOriginal (line 19) h(1) = plot(1:1:seq.Count,seq.ThermalImage.GetValueFromSignal(im(165,143)));

[Eric]

Use h1 and h2 instead of indexing. h is probably already indexed and I didn't know/realize that.

[Nathan B]

Whenever I try to add a second plot I start to get an error in the line below. For example, I left everything the same but added a h2 = plot(...) below the first one (h = plot(...) ) and got the error in that line even though h2 wasn't used after that. If I put the h2 = plot(...) above the h = plot(...) it runs as it normally would.

set(h,'XData',1:1:seq.Count)

Error:

Error using matlab.graphics.chart.primitive.Line/set

Invalid or deleted object.

[Eric]

You need to set “hold on” before the second call to plot to keep it from deleting the first line.