<p>You definitely need to know distances and angle of view of the camera.  For example, if you add lines that are slightly further apart, they will be at different angles.  Like a multi-lane highway.</p>

<p><a href="https://i.sstatic.net/AjNpc.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/AjNpc.jpg" alt="enter image description here"></a></p>

CC BY-SA 3.0
2018-02-06T19:31:00.137Z
2018-02-06T19:31:00.137Z
Wyck
<p>Suppose I have parallel lines running along the ground (into the horizon). If I have a camera and I know its tilt angle, is there a way to calculate the slopes of the lines as projected to the 2D image plane? That is, the green angles:</p>

<p><a href="https://i.sstatic.net/SQyPf.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/SQyPf.png" alt="enter image description here"></a></p>

<p>However, the distance from the lines are not known. What parameters of the camera are used in the calculation?</p>

<projections><perspective>
Determining slopes of lines in perspective projection
John M.
# Determining slopes of lines in perspective projection

(Asked by: username_0 on 2018-02-06)

Suppose I have parallel lines running along the ground (into the horizon). If I have a camera and I know its tilt angle, is there a way to calculate the slopes of the lines as projected to the 2D image plane? That is, the green angles:

[![enter image description here](https://i.sstatic.net/SQyPf.png)](https://i.sstatic.net/SQyPf.png)

However, the distance from the lines are not known. What parameters of the camera are used in the calculation?

**Tags:** projections, perspective


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## 1 answers

### Answer by username_1 on 2018-02-06. Score: 1

You definitely need to know distances and angle of view of the camera. For example, if you add lines that are slightly further apart, they will be at different angles. Like a multi-lane highway.

[![enter image description here](https://i.sstatic.net/AjNpc.jpg)](https://i.sstatic.net/AjNpc.jpg)


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