octomap can't be built with Visual Studio and ninja generator because CMakeLists builds both static and shared, and OUTPUT_NAME of shared and static targets are identical. Therefore static lib and import lib of dll have the same name.
This is illegal with ninja when both targets live in the same dependency tree.

One solution would be to give a different name to the static or shared lib if Visual Studio.

Moreover it would be nice to provide options to disable shared or static (we have to patch CMakeLists of octomap and octomath in the public repository of conan (package manager) because its policy is to provide either static or shared depending on an option, not both in the same package).