Draw multiple polygons on figure

Hi all,

I'm relatively new to matlab and am currently trying to use impoly to draw multiple 4-sided polygons on a figure and then use getposition to get each individual position. I have this working for one polygon, but I'm not sure how to do it for multiple polygons on the one figure.

vidObj = VideoReader('final1.mp4');
vidHeight = vidObj.Height;
vidWidth = vidObj.Width;
s = struct('cdata',zeros(vidHeight,vidWidth,3,'uint8'),...
    'colormap',[]);
k = 1;
while hasFrame(vidObj)
    s(k).cdata = readFrame(vidObj);
    k = k+1;
end

% select ROI
figure('Name','Please Click to Select ROI');
imshow(s(1).cdata)

h = impoly();
h2 = impoly();
api = iptgetapi(h);
api.setColor('green');
api.addNewPositionCallback(@(p) title('Select Region of Interest'));

api.addNewPositionCallback(@(p) title('Select 2nd Box'));

pos = ceil(getPosition(h))
pos2 = ceil(getPosition(h2))
patch(pos,pos2,'red')

x = pos;
y = pos2;
c = [0; 1];
FigHandle = figure('Position', [100, 100, vidWidth, vidHeight])
patch(x,y,c);

pos = ceil(getPosition(h));

% make binary mask
masked = poly2mask(pos(:,1),pos(:,2),vidHeight,vidWidth);
minX = min(pos(:,1));
maxX = max(pos(:,1));
minY = min(pos(:,2));
maxY = max(pos(:,2));

figure('Name','Region of Interest');
roi_frame = s(1).cdata(minY:maxY,minX:maxX,:);
roi_frame(:,:,1) = (roi_frame(:,:,1) .* uint8(masked(minY:maxY,minX:maxX)));
roi_frame(:,:,2) = roi_frame(:,:,2) .* uint8(masked(minY:maxY,minX:maxX));
roi_frame(:,:,3) = roi_frame(:,:,3) .* uint8(masked(minY:maxY,minX:maxX));
imshow(roi_frame)

% write out a temporary video file of the ROI for use in various algo's
% add text to video and write out
v = VideoWriter('roi_video.avi');
open(v);
for k = 1:length(s)
%     frameOut = s(k).cdata(pos(2):pos(2)+pos(4),pos(1):pos(1)+pos(3),:);
    roi_frame = s(k).cdata(minY:maxY,minX:maxX,:);
    roi_frame(:,:,1) = (roi_frame(:,:,1) .* uint8(masked(minY:maxY,minX:maxX)));
    roi_frame(:,:,2) = roi_frame(:,:,2) .* uint8(masked(minY:maxY,minX:maxX));
    roi_frame(:,:,3) = roi_frame(:,:,3) .* uint8(masked(minY:maxY,minX:maxX));
    writeVideo(v,roi_frame);
end

close(v);

Any help would be great!

Answer 1

[KSSV]

Are you looking for something like this?

x = linspace(0,1,10) ; 
y = linspace(0,1,10) ; 
[X,Y] = meshgrid(x,y) ;
surf(X,Y) ;
view([0 90])

If not explain your needs further.

[Gee]

Sorry, I should have been more clear. I'm trying to draw 4 sided polygons by hand with impoly (see added code above);

Answer 2

[Image Analyst]

Put it in a while or for loop.

[Gee]

I tried putting it in a while loop, but it won't let me draw on the figure:

while l <= 4
    h(l) = impoly();
    api = iptgetapi(h(l));
    api.setColor(l);
    api.addNewPositionCallback(@(p) title(['Draw ROI for box ' l]));
    pos(l) = ceil(getPosition(h(l)))
    l = l + 1;
end