In the first case you can do it several different ways:
1) two markers that define center and radius
2) two diametral positions on the surface . The center marker can then be parameterized to be the center point between those markers. You have to define the direction some other way.
3) Use three markers that will now make up a plane whose normal is the direction of the cylinder. A bit more complex to define the radius.
The second case is trivial. Use LOC_RELATIVE_TO(LOC_CYLINDRICAL(radius, angle, height), center_marker) to define the location of markers on the surface of a cylinder with given radius.
my point is , Can i add points/marker on the surface of the cylinder so that if i change the radius of the cylinder, the points/marker should be attached to the model itself.
or
if i change the radius of the cylinder the points /marker move wrt to the origin.
i have attached the image for your better understanding
