I'm using Altium designer 17 and I want to make a 3D layout of my board. My only problem is that whenever I place a piece on the pcb, the component is flashing green and it says Collision. It Collision even if nothing is touching the pcb. Exemple this transfo:
It sounds like your vertical component clearance is set to infinite, or at least a ridiculous number. I generally set mine to 0mm unless a specific application requires that I change it. You can modify this value in the Design -> Rules window (shortcut D-R), down near the bottom under "Placement". Look for "Component Clearance" and set the "Minimum Vertical Clearance" to 0mm. If the radio button to the left is set to "Infinite" you'll have to change it to "Specified" before adjusting the number. See if that helps.
Right Click on Component's Footprint > Component Action > Manage 3D Bodies
Under Column: Body State Click on "In Component X" (where X is the name of the component), it will change to "Not in Component X".
What it does is that it disables the invisible 3D boundary around the component so that you can place a custom 3D boundary.