3D point cloud
I am trying to get a 3D point cloud using the following code: output_dir = 'C:\Users\Xyz\Desktop\Matlab'; %%set up webcam delete(imaqfind) leftCam = imaq.VideoDevice('winvideo', 2, 'YUY2_640x480'); rightCam = imaq.VideoDevice('winvideo', 1, 'YUY2_640x480'); %%load stereo parameters if required if ~exist('stereoParams', 'var') load stereocalibration.m; end ax = axes; maxDepth = 5; clear maxdepth; while true imageLeft = step(rightCam); imageRight = step(leftCam); [J1, J2] = rectifyStereoImages(imageLeft, imageRight, stereoParams); disp = disparity(rgb2gray(J1), rgb2gray(J2), 'DisparityRange', [0, 112]); pointCloud = reconstructScene(disp, stereoParams) ./1000; z = pointCloud(:,:,3); z(z<0) = NaN; z(z>maxDepth) = NaN; pointCloud(:,:,3) = z; if ~ishandle(ax) break; else showPointCloud(pointCloud, J1, 'VerticalAxis', 'Y', 'VerticalAxisDir', 'Down', 'Parent', ax); xlabel('X (m)'); ylabel('Y (m)'); zlabel('Z (m)'); xlim(ax, [-.8, .8]); ylim(ax, [-.8, .8]); zlim([ax, maxDepth]); drawnow; end end release(leftCam); release(rightCam); ERROR: Error using matlab.graphics.axis.Axes/horzcat Cannot convert double value 5 to a handle. MATLAB R2015a
Prashant Kumar answered .
2025-11-20
ax = axes.
When you do that in MATLAB, for example...
plot(1:5)
>> ax = axes
ax =
Axes with properties:
XLim: [0 1]
YLim: [0 1]
XScale: 'linear'
YScale: 'linear'
GridLineStyle: '-'
Position: [0.1300 0.1100 0.7750 0.8150]
Units: 'normalized'
Show all properties
As you can see, the result is a handle to the axes in a figure.
Then later on, you did this:
xlim(ax, [-.8, .8]); ylim(ax, [-.8, .8]); zlim([ax, maxDepth]);
Do you see that in the calls to xlim and ylim, you used one form, yet when you called ylim, for some reason, you did something completely different?
In fact, inside the call to zlim, you tried to catenate the number 5 to a graphics handle?
maxDepth = 5;
Now, go back and READ THE ERROR MESSAGE YOU GOT. maxdepth is the number 5.