Should IPVM Remove Imager Size And Focal Length From Calculator?

JH
John Honovich
Nov 09, 2017
IPVM

We are considering removing imager size and focal length from the calculator.

The two main reasons:

  • The results of entering these inputs are often wrong, i.e. imager size and focal length frequently do not match the actual cameras' HFoV (because of how the manufacturer uses the sensor, lens, etc.)
  • We have the actual HFoV for 5,400+ models (and growing) inside the Calculator for members to pick from.

The reason why imager size and focal length are there is that, in the old days, lens were frequently sold separately from the camera, ergo you had to enter these parameters in. Today, overwhelmingly cameras ship with integrated lens and therefore the HFoV is known and verified by the manufacturer.

Moreover, we are imminently going to make it a lot easier to submit new models to be added. When a user enters a model name and it is not found, we will provide a link to automatically submit that for entry. Expect that next week.

As for these fields, vote and comment inside.

U
Undisclosed #1
Nov 10, 2017
IPVMU Certified

No, keep them!

IMHO, the biggest problem with the HFOV calculations being wrong is that you don’t have the all of the correct imager dimensions to choose from.

Sensor sizes like 1/3” and 1/4” refer only to the nominal diagonal length of the sensor.  The calculator assumes a width and height that is comptabile with that diagonal, however there could be many different sizes, due to different aspect ratios.  In practice, there is just one or two others, often an 16:9 one.

What I think you should do is this, choose the width and height of the sensor based on the image sensor format, e.g. 1/3” AND the resolution. Take the sensor width/height that most closely matches the  aspect ratio of the resolution.

Using this method and assuming the highest resolution for the camera is input, IMHO, the accuracy of the resulting HFOV will be improved.

Ideally, I would like to input the width/height manually.  Or you could have multiple listings for 1/3” and 1/3” HD, for example.

 

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JH
John Honovich
Nov 10, 2017
IPVM

Ideally, I would like to input the width/height manually.

Of the imager or?

U
Undisclosed #1
Nov 10, 2017
IPVMU Certified

Yes, but I know that’s probably not of much use to most.

(1)
JH
John Honovich
Nov 10, 2017
IPVM

IMHO, the biggest problem with the HFOV calculations being wrong is that you don’t have the all of the correct imager dimensions to choose from.

Ok, let's say we add all of them in. How will users know which one to pick? Keep in mind that almost every camera datasheet lists limited information about the imager - no imager dimension or imager part number, etc.

U
Undisclosed #1
Nov 10, 2017
IPVMU Certified

Ok, let's say we add all of them in. How will users know which one to pick?

I was saying do it like this:

What I think you should do is this, choose the width and height of the sensor based on the image sensor format, e.g. 1/3” AND the resolution. Take the sensor width/height that most closely matches the aspect ratio of the resolution.

JH
John Honovich
Nov 10, 2017
IPVM

I get that should help statistically, i.e., if its wrong 70% of the time, maybe it's only wrong 40% (or something).

But some cameras support HD resolution max but use a 4:3 aspect ratio sensor. It will be still be wrong with those. And some manufacturers do other techniques in terms of cropping resolution or how they use the lens, etc.

The metapoint is, to me, that even that won't fix it and we'll still have people with erroneous HFoV angles. And, in 2017, almost everytime someone has a question about HFoV, it's a camera with an integrated lens and a clearly listed HFoV.

U
Undisclosed #1
Nov 10, 2017
IPVMU Certified

But some cameras support HD resolution max but use a 4:3 aspect ratio sensor. It will be still be wrong with those.

That’s true, there were a couple I have come across like that.

On the other hand, I haven’t seen any like that in years, so I am wondering whether that was just because they wanted to claim HD...

To be clear, we are talking about cameras that, in their max stated resolution, do not use all the pixels of the sensor.  

I think that those cameras are far and few between now, maybe less than 2%?  

If anyone has any examples, I would be interested in seeing them, maybe there is a good reason for cropping the sensor.

I would add if any manufacturer is not using only a significant portion of the sensor, then it’s a bit misleading to even say it’s a 1/3” sensor, because the unused pixels might as well not even be there.

So, if you decide to keep the sensor selection, I think this will definitely improve accuracy, esp. with all those omnivision sensors.

JH
John Honovich
Nov 10, 2017
IPVM

I think this will definitely improve accuracy, esp. with all those omnivision sensors.

So how does the Calculator or the user know if it is an Omnivision sensor or not?

UI
Undisclosed Integrator #2
Nov 10, 2017
I see value in the imager size relative to the quality of the final image. IMHO. As for FOV what would happen to the tool output?
JH
John Honovich
Nov 10, 2017
IPVM

You don't need the imager size to determine the HFoV as the HFoV (in degrees) is almost always listed on the camera's specification sheet. And, ultimately, that is what the user should care about (whether it's 80° or 110° etc.). Entering the focal length and imager size is a process to estimate (often wrongly) what the HFoV is.

Avatar
Craig Mc Cluskey
Nov 10, 2017

The reason why imager size and focal length are there is that, in the old days, lens were frequently sold separately from the camera, ergo you had to enter these parameters in. Today, overwhelmingly cameras ship with integrated lens and therefore the HFoV is known and verified by the manufacturer.

But there still are box cameras sold without lenses.

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JH
John Honovich
Nov 10, 2017
IPVM

Yes, but box camera usage, without the lens being included, is 1 out 30 or 1 out of 50 now.

Looking at the feedback, I think the solution is to hide it by default and let people click on an icon to expose it. This way, the rare people who really need this and know the issues involved can select it, while everyone else is oriented to select a model or find the AoV.

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Avatar
Ethan Ace
Nov 10, 2017

I think the solution is to hide it by default and let people click on an icon to expose it.

I think exactly this. I can see power users looking at it and I can see using it for educational purposes (showing differences in AOV between different imagers), but I cannot think of everyday use for it. 

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JH
John Honovich
Nov 10, 2017
IPVM

Mockup:

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Avatar
Craig Mc Cluskey
Nov 10, 2017

Looking at the feedback, I think the solution is to hide it by default and let people click on an icon to expose it.

Yes, that is a good solution. The wording of your original question, however, did not suggest this as a possibility (perhaps because you had not thought of it then).

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SC
Scott Clingan
Nov 10, 2017
IPVMU Certified

That was exactly my thought when I first read the question.  Hide to reduce complexity and general use but leave it as an "Advanced" option.  I like the mock-up.

UM
Undisclosed Manufacturer #3
Nov 10, 2017

John

 

Yes, exact models numbers in a look-up table will be helpful, but having a quick "estimator" that provides approximate answers is very useful. 

Suggest you consider adding a disclaimer as the the accuracy of results, and a link to the HFoV table.

After all, actual site installation factors, and end users' view preferences can, and often do, change from the original design calculations, so a less-than-perfect-, quick process is of great value.

UM
Undisclosed Manufacturer #4
Nov 13, 2017

You should keep them. Or, just allow them for box cameras shipped without lens. Maybe it is not so precise, but at least, give us an idea where we are with calculations.

Typical example Sony VB770 with FF imager.    

GT
George Tavares
Nov 14, 2017

Hide to reduce complexity and general use but leave it as an "Advanced" option. 

JH
John Honovich
Dec 05, 2017
IPVM

Updated: this is now live, focal length and imager size are now hid by default by can be easily expanded, demo:

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