  The nearby Herbig Be star HD100546 is known to be a laboratory for the study
of protoplanets and their relation with the circumstellar disk that is carved
by at least 2 gaps. We observed the HD100546 environment with high contrast
imaging exploiting several different observing modes of SPHERE, including
datasets with/without coronagraphs, dual band imaging, integral field
spectroscopy and polarimetry. The picture emerging from these different data
sets is complex. Flux-conservative algorithms images clearly show the disk up
to 200au. More aggressive algorithms reveal several rings and warped arms
overlapping the main disk. The bright parts of this ring lie at considerable
height over the disk mid-plane at about 30au. Our images demonstrate that the
brightest wings close to the star in the near side of the disk are a unique
structure, corresponding to the outer edge of the intermediate disk at ~40au.
Modeling of the scattered light from the disk with a geometrical algorithm
reveals that a moderately thin structure can well reproduce the light
distribution in the flux-conservative images. We suggest that the gap between
44 and 113 au span between the 1:2 and 3:2 resonance orbits of a massive body
located at ~70au that might coincide with the candidate planet HD100546b
detected with previous thermal IR observations. In this picture, the two wings
can be the near side of a ring formed by disk material brought out of the disk
at the 1:2 resonance with the same massive object. While we find no clear
evidence confirming detection of the planet candidate HD100546c in our data, we
find a diffuse emission close to the expected position of HD100546b. This
source can be described as an extremely reddened substellar object surrounded
by a dust cloud or its circumplanetary disk. Its astrometry is broadly
consistent with a circular orbital motion on the disk plane.
