MATLAB: How to set projection of point cloud visualization

Computer Vision Toolboxpcplayerprojection

I'm using pcplayer to visualize a colored point cloud.

player1 = pcplayer([-1 1],[-1 1],[-1 1]);
view(player1,vertices,color)

I cannot find a way to set projection and camera angle for pcplayer – is it possible? If not, is there another solution?

Best Answer

You need to use the axes of the pcplayer object.

For example,

% Create a pcplayer viewer
player = pcplayer([0 1], [0 1], [0 1]);
% View a point cloud
view(player, rand(1000,3));
% Query camera view angle
camva(player.Axes)
% Set camera view angle
camva(player.Axes, 15)

Related Solutions

MATLAB: Is the pointsToWorld back-projection inverted

You may need to convert the camera world pose to extrinsics using cameraPoseToExtrinsics:

[worldOri,worldLoc] = estimateWorldCameraPose(worldPoints(:,[1 2]),worldPoints,intrinsics);
[rotationMatrix,translationVector] = cameraPoseToExtrinsics(worldOri,worldLoc);
backProjectPoints = pointsToWorld(intrinsics,rotationMatrix,translationVector,imagePoints);

MATLAB: Does the view zoom in and out randomly when I try to rotate around the 3-D image

You must do two things in order to avoid seeing a "bouncing" affect as you rotate around a 3-D image.

1. Set 'CameraViewAngleMode' to 'Manual'

The 'CameraViewAngle' property determines the camera field of view. Changing this value affects the size of graphics objects displayed in the axes. By default, the 'CameraViewAngleMode' is set to 'Auto' so that MATLAB adjusts the view angle automatically. Setting 'CameraViewAngleMode' to 'Manual' prevents any unexpected adjustments. You can set this mode to manual with the following command:

set(axes_handle,'CameraViewAngleMode','Manual')

where "axes_handle" is the handle to axes (usually obtained by using the GCA command).

2. Setting the axes aspect ratio to 1.

Set the axes aspect ratio to [1 1] so that equal tick mark increments on the x-,y- and z-axis are equal in size. You can do this with the command:

axis equal

This step is very important in order to properly rotate around your image. As the camera moves through your coordinate system, it is important that each tick have equal value. If the tick marks in one direction are much larger than the tick marks in another direction, then the camera will appear to zoom in and out as it changes axis alignments.

The following code domonstrates how these two steps produce a smoothly rotating animation.

% This part of the code draws an arbitrary image
      figure('renderer','zbuffer','color','k')
      [x,y,z]=sphere;
      hold on
      for j=[-1 1],
          patch([-1 -1 1 1],[-1 1 1 -1],[j j j j],'b')
          patch([-1 -1 1 1],[j j j j],[-1 1 1 -1],'r')
          patch([j j j j],[-1 -1 1 1],[-1 1 1 -1],'g')
          surf(x+3*j,y,z)
          surf(x,y+3*j,z)
      end
      axis([-5 5 -6 6 -5 5],'off')
      view(3)
%%%%%%%%%%%%%%%%
% Get the current view angle
      [az,el]=view;
      el=el+15;
%%%%%%%%%%
% The next two lines prevent the "bouncing" affect as you rotate the camera
      set(gca,'cameraviewanglemode','manual')
      axis equal
% Now rotate around the image
      for j=10:10:360,
          view(az+j,el)
          pause(0.1)
      end

Best Answer

Related Solutions

MATLAB: Is the pointsToWorld back-projection inverted

MATLAB: Does the view zoom in and out randomly when I try to rotate around the 3-D image

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