I'm developing an app that needs a certain 3d object hovering in front of the user when he looks through the camera. Using vuforia I need to use an Image marker to place an object. Is it possible to do the placing without an image marker?
I also don't want to use Unity 3D as I'm developing a native Android app that has other functionalities too.
Instead of the image target, use mid-air target in Vuforia. See Placing Floating Content in your Environment in this article for the detailed explanation.