# Measurements

## Angle

In order to measure the magnitude of an angle you need to pinpoint 3 points on the picture. Please note that a picture projects a 3-dimensional object into a 2-dimensional object, and hence, you can accurately measure the magnitude of angles which lie in a plane. Therefore, when you take a picture of a 3-D object make sure that you capture only one side of this object, and you can measure the magnitude of the angles on that side. In the case where the object does not have a uniform surface (i.e., the human face), you may need to take more than one pictures. For example, if you take a picture of a human being from the front, you can measure the magnitude of the angle that his/her hands make with the chest. If, instead, you take a picture of a running person from the side, you can measure the magnitude of the angle of his/her knee.

## Length

In order to measure the length of an object you need to pinpoint 4 points on the picture. The first two points designate the yardstick, and the other two points the object whose length you want to measure. The length of an object is measured relative to the length of a yardstick.

The yardstick can be any object! It could, for example, be a pencil or your credit card. It needs to be an object whose dimensions are known, however. Place the yardstick near the object of interest, and position the yardstick so that its larger side is aligned with the side of the object that you want to measure. Namely, if the yardstick is a pencil, and you need to measure the height of the object, place the pencil vertically next to the object. If, instead, you want to measure the length, place the pencil horizontally. Next, you pinpoint the two ends of the yardstick (blue color), and then you pinpoint the length of the object of interest. Once you have pinpointed 4 points, click on the “Calculate” button, give the length of the yardstick, and iPinPoint will calculate the length of the object of interest.

If you tap on the + button you can measure the length of another object. In this case, you need to add two more points for the new object. You can keep tapping on the + button as many times as you like. Each time you tap on it, you need to add two more points. The length of each new object is computed relative to the length of a yardstick.

## Triangle

You can measure the length of each side and the angle of each vertex of the triangle. You need to pinpoint 5 points: The first 2 points are for the yardstick, and the other 3 are for the triangle. If you give the length of the yardstick. then iPinPoint will also compute the area of the triangle.

## Circle

You can measure the radius, area and perimeter of a circle. You need to pinpoint 5 points: The first 2 points are for the yardstick, and the other 3 points are located on the perimeter of the circle. When you pinpoint these 5 points, iPinPoint will compute the angle between these 3 points. Once you give the length of the yardstick, iPinPoint will compute the radius, area and perimeter of the circle.