objective c - Height and width of object using camera in iOS -

I am working on a small educational demo which should measure the height and width of the object using the iOS camera.

Edit:

I have a new theory to measure the breadth of an object.

In the image above, If I can get angle and α, then I can use the trigonometry to get the width of the unknown side. I already have the value of B1 and B2.

Old:

Right now, I'm focusing only on measuring the length. According to my knowledge this should be 3 phase process.

1. The user draws one end of the object.
2. The user captures the other end of the object.
3. The user draws the center of the object (please tell me a better way for them)

I get the estimated measurements using the above process, but the third step , In which the user draws the center of the object. I want to show the indicator location on the screen (as the camera overlay) so that the user can determine the center of the object.

Similarly, I am doing this now.

How can I get indication location for the third step ?

Note: Please suggest alternate / best ways to make this possible. I would like another suggestion thanks. !!

First of all I have to appreciate your work done by you. Another good thing is the way to explain, salami !!!!!

After reading your question, I think that you do not need a code, you can do it. I think you only need direction

According to your explanation, you want to record the rotation angle of the device.

If you want to measure the rotation angle, then you have to use computation reading. But the user reading will change if the user falls on the device. Then you have to use the accelerometer to measure the device's tildings.

In short, you have to make some combinations and equations of both the composition and accelerometer reading.

If you want more information to apply it, you can ask me.

Hope this will help you .... .