Getting "squared" point clouds with 3d lidar. about webots

[ShuffleWire]

Got the same issue here...
Never used rotating lidar, so I can't really help...

[TonyWelte]

I couldn't reproduce this on the master branch by manually compiling the project. Using the nightly build versions 2023b-rev1 seems to work fine, but version 2024a does appear to produce points rotated by 180 degrees.

Looking at the diff between master and develop, it appears there are some updates introduced on develop:

--- a/src/webots/nodes/WbLidar.cpp
+++ b/src/webots/nodes/WbLidar.cpp
@@ -362,7 +362,8 @@ void WbLidar::copyAllLayersToMemoryMappedFile() {
     maxWidth = ((double)w / 2.0) * (1.0 + ratio);
 
     double tmpAngle =
-      (fabs(mPreviousRotatingAngle / (2.0 * M_PI)) - floor(fabs(mPreviousRotatingAngle / (2.0 * M_PI)))) * (2.0 * M_PI);
+      (fabs((mPreviousRotatingAngle - M_PI) / (2.0 * M_PI)) - floor(fabs((mPreviousRotatingAngle - M_PI) / (2.0 * M_PI)))) *
+      (2.0 * M_PI);
     if (tmpAngle < 0)
       tmpAngle += 2.0 * M_PI;
     widthOffset = resolution * (tmpAngle / (2.0 * M_PI));
@@ -383,7 +384,7 @@ void WbLidar::copyAllLayersToMemoryMappedFile() {
         memcpy(data + (i + 1) * resolution + minWidth + widthOffset, mTemporaryImage + width() * (int)(i * skip) + minWidth,
                sizeof(float) * abs(minWidth + widthOffset));
         memcpy(data + i * resolution, mTemporaryImage + width() * (int)(i * skip) - widthOffset,
-               sizeof(float) * (maxWidth + widthOffset));
+               sizeof(float) * abs(maxWidth + widthOffset));
       }
     }
   }

These changes have been introduced by #6324. There must have been a conflict between the changes I made in #6417 and those of #6324. There is a missing - M_PI when theta0 is computed for rotating lidars.

Note: The "tilt angle" can also produce point clouds slightly rotated. #37

[ShuffleWire]

Hello,
Take a look at #6417
Try to build webots from source on master, or get a nightly, until the new fixed version is out.

[francocipollone]

@ShuffleWire Thanks for quick reply!

[francocipollone]

@ShuffleWire When using the nightly build even tho that error is fixed I noticed now something weird going on when using rotational type.

Equal configuration than before + rotational type

It is like the pointcloud is rotated 180 deegres.
It even happens with the default lidar example.

[ShuffleWire]

That should be it ! Could you make a quick PR to fix that ?

[ShuffleWire]

Closing because PR is merged