# Vision sensor FOV measurements

I’ve been asked a few times about the vision sensor field of view.
I wrote in this thread that is was 67 deg, that was based on quick measurements with a target pretty close to the sensor, that number is close but not correct.

@Windows10010 posted earlier today here that they thought it was 30 deg, that seemed way too narrow from what I remembered.

I used to do this type of measurement often as I worked in the film industry for a camera manufacturer. It’s pretty easy to do, harder with this sensor due to lack of resolution and ability to focus, but I made another attempt today, here are the results.

The general idea is to shoot a target of known size at a known distance and use trig to calculate FOV. This does ignore any lens distortion, measuring FOV using a full width target may give a different result to using a target that only fills part of the frame, but with only 316 horizontal pixels to work with I ignored all that for this experiment.

vision sensor was placed 3350mm from the far wall in my office (just happens to be the edge of my desk), I setup a target with a 2000mm width, just some tape placed on the wall. Based on that setup, horizontal field of view is 61 deg.

This means that at that distance (about full competition field width) each pixel represents about 12.5mm.

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Sound right to me. We got roughly the same angle with a different approach (set one edge looking down a line, find the line for the other edge, measure the angle). I was surprised we were getting 10% less than the 67° I’d seen listed, but the measurements seemed pretty good.

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Ohh, I almost had fallen asleep when I made the post last night… So I typed the wrong number. 30 deg is actually half of the horizontal FOV that I measured. So the real horizontal FOV should be 60 deg as same as @jpearman said in the post. The method I used was just about some simple trigonometry functions. I also have verified my result using the same method with different settings for 3 times. The results seemed to be no different. I will try to measure the vertical FOV later…

The environment in which I conducted the experiment was much more compact compared to yours, which I think may enhance the accuracy of the results. I pasted a piece of paper with marks of constant distances on the wall located in front of my desk. Then I adjusted the distance between the sensor and the paper to make sure that the marks are by the horizontal edge of the frame. And I recorded the distance and did some calculations . shown below:(also includes my experiment data)

ps: Why am I regarded as a new user here while I have been playing with vex robotics for almost 4 years and cannot upload more than one image?

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vertical FOV should simply be 61 * (212 / 316 ). 41 deg.
The lens projects a circular image. The pixels are square, that is, the photo sites on the sensor have the same vertical and horizontal spacing.

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because you only joined the forum 10 hours ago. Once you have viewed a few more topics you will be promoted to TL1 (trust level 1)

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Ok I will do that later.>_<