How to combine: image - optical flow - coordinate system (axis2pixels)

hi everyone,

my goal is to calculate windspeed from cloudimages (frames).

I use Lucas Kanade for Flow Estimation.

Unfortunalty iam stucked by plotting my results:

-i want the output diagramm/image/flowfield full frame without white border

-moreover i would like to add axis with the pixel units (tried imref2d)

-and a grid

I am sure there is a way. but who knows him?

% display optical flow
step = 30;
imshow(im_2);

[w,h] = size(optical_flow_u);
u_down = optical_flow_u(1:step:end, 1:step:end);
v_down = optical_flow_v(1:step:end, 1:step:end);

[m,n] = size(im2_level);
[X,Y] = meshgrid(1:n, 1:m);
X_down = X(1:step:end, 1:step:end);
Y_down = Y(1:step:end, 1:step:end);

hold on;

quiver(X_down, Y_down, u_down, v_down, 0.5, 'color',[1 0 0]);

Answer 1

[Aishwarya]

Hi Paul,

As per my understanding you are facing difficulties in changing the plot properties of the flow estimation output.

To address your questions.

Change the property of the figure:

• Change “Position” property of the figure window according to image size and position of figure required.

        f = figure;  
        f.Position = [10 10 500 500]; 

To add axis and grid to the plot:

• “axis on” will add the axis in pixel units. Consider making the following changes in the code:

        hold on;
        quiver(X_down, Y_down, u_down, v_down, 0.5, 'color',[1 0 0]); 
        
        % Add axis and label them 
        axis on; 
        xlabel('X (pixels)'); 
        ylabel('Y (pixels)'); 
        
        % Turn on grid 
        grid on; 
        hold off; 
        

Hope this helps!

Regards,

Aishwarya Palli