Problem with Ray-Picking by C++

I programmed Ray-picking by C++

here is code :

Controller->CastToPlayerController()->DeprojectScreenPositionToWorld(MousePos_2D.X, MousePos_2D.Y, WorldOrigin, WorldDirection);

TraceEnd = WorldOrigin + WorldDirection * 65536.0f;

GetWorld()->LineTraceSingle(TraceHitResult, WorldOrigin, TraceEnd, TraceParam, TraceObjectParam);

MouseWorldPosition_3D = TraceHitResult.ImpactPoint;

but…

I want to mouse picking ONLY at floor(ground)

but picking was all object.

So…

Can I adjust Actor’s property(ex-corn’s property at picture) to ignored at mouse picking

I dont intended “corn top”

just want overlap corn

How can i do that?