If the image/object distance is measuring opposite to the incident ray then the sign should be (-)negative

if the image/object distance is measuring along the direction of incident ray then the sign should be (+)positive

Explanation of the Second Point of New Cartesian Sign Convention:
All distances parallel to principal axis are measured from the pole of the mirror. This convention helps in determining the sign of distances accurately in ray optics.

Distances Measured from the Pole:
- When measuring distances parallel to the principal axis, we start from the pole of the mirror. The pole is the point where the principal axis intersects the mirror surface.
- Distances are measured along the direction of the incident light rays or reflected light rays.

Sign Convention:
- If the object is placed on the same side as the incident light rays, the distance is considered positive.
- If the object is placed on the opposite side of the incident light rays, the distance is considered negative.
- Similarly, for images formed by the mirror, distances are measured from the pole following the same sign convention.

Importance of this Convention:
- This convention simplifies the calculations involved in ray optics by providing a consistent way to determine the sign of distances.
- It helps in accurately predicting the nature and location of images formed by mirrors.
In conclusion, the second point of the New Cartesian Sign Convention states that all distances parallel to the principal axis are measured from the pole of the mirror. This rule provides a standardized approach for determining the sign of distances in ray optics, making calculations more straightforward and accurate.