unknown voxels in space that should be mapped as "free"?

[Jacopo Banfi]

Hello everyone,

I am using octomap with a stereo camera as sensor and I noticed, when I am iterating through the octree leaves, that some voxels in the surrounding of the camera (up to where the rays are supposed to hit an object / wall) are actually unknown, while I was expecting them to be existing and labeled as free since it looks like they should lie on at least one of the rays being casted.  Is that an expected behavior due to e.g. approximations introduced by the raycasting operation (my voxels are 20x20cm)?

Thanks in advance!

Jacopo