This research applies the Pinhole (PH) Camera Model method to calculate car speed in a video sequence by taking object displacement distance in the frame. The main contribution in this paper is the new calculation method called Diagonal Pinhole (Diagonal-PH). It has a capability in measuring diagonal and zigzag movement. This research considers three scenarios, i.e. overtaking motion, lane changing path and straight-line movement. The performance of the proposed system is evaluated using Root Mean Square Error (RMSE). The results show that the diagonal-PH method provides smaller RMSE than a vertical-PH method for each scenario. This proves that the modified pinhole has better accuracy for car speed detection in all scenarios
