Kinect Point Cloud Floor is sloped compared to Walls

Hi

So I am using a kinect to get a point cloud and then for now I'm just saving it as a .ply

The issue is that the walls and floors are not at 90 degrees to each other

I get the pitch from the accelerometer so that I can rotate the whole point cloud to be level (for now assuming roll is zero)

But as you can see below, although the walls are pointing straight up, the floor looks sloped

https://gfycat.com/famousfakearthropods

I am pretty sure it's not the sensor itself because I have played around with KinectFusion and that worked perfectly fine

Here's a link to view the point cloud on SketchFab

https://sketchfab.com/3d-models/test-pt-1dc18091cbcd41f2b108868e0a7a5fa8

(I have also attached the .ply to this post)

Thanks :)

Script:

%--------------------------------------------------------------------------
%INITIALISE KINECT
%--------------------------------------------------------------------------
clc;
disp('Capturing Point Cloud');
disp('----------------------------------');

imaqreset;
disp('Imaq Reset');

colourVid = videoinput('kinect',1);
disp('Colour Video Acquired');
src = getselectedsource(colourVid);
disp('Colour Video Source Acquired');

colourDevice = imaq.VideoDevice('kinect',1);
disp('Colour Device Acquired');
depthDevice = imaq.VideoDevice('kinect',2);
disp('Depth Device Acquired');

src.CameraElevationAngle = 0;

disp('Kinect Initialised');


%--------------------------------------------------------------------------
%CAPTURE POINT CLOUD
%--------------------------------------------------------------------------
src.CameraElevationAngle = -20;
  
colourImage = step(colourDevice);  
depthImage = step(depthDevice);

ptCloud = pcfromkinect(depthDevice,depthImage,colourImage);
disp('Point Cloud Captured');


%--------------------------------------------------------------------------
%TRANSFORM POINT CLOUD
%--------------------------------------------------------------------------
pitch = atan(src.Accelerometer(3) / sqrt( (src.Accelerometer(1)*src.Accelerometer(1)) + (src.Accelerometer(2)*src.Accelerometer(2)) ) );
T = makehgtform('xrotate',pitch);
tform = affine3d(T);
ptCloudTransformed = pctransform(ptCloud,tform);
disp('Point Cloud Transformed');


%--------------------------------------------------------------------------
%SAVE POINT CLOUD AS PLY
%--------------------------------------------------------------------------
pcwrite(ptCloudTransformed,'TestPT.ply','Encoding','ascii');
disp('Point Cloud Saved');


%--------------------------------------------------------------------------
%CLEAN UP
%--------------------------------------------------------------------------
delete(colourVid);
release(colourDevice);
release(depthDevice);