Cats and narrow hallway - lens angle and 90 deg rotation

P

pila

n3wb
Sep 28, 2015
25
2
Croatia
I want to mount a camera just above my doors (2 m / 7 ft). Camera must cover floor right to the doors and cover a hallway which is narrow (1,5 meters on the camera end and about 4 meters long). Most likely candidate for the camera is Hikvision Ds-2cd2132F-IS. Questions.

1. Do I need 2,8 or 4 mm lens will do? As I want to see if any of our cats are sleeping / walking on the doorway (waiting to be let in) camera angle must cover floor completely to the doors. This is a must! Upper limit should be almost horisontal line ideally so I can see faces of people of regular hight coming. That is 90 deg desired coverage up-down or just a bit less. I do not want more (as lights are on the ceiling) but can accept a bit less coverage (e.g. 80 deg).

2. Could I rotate camera on the wall 90 deg (e.g. clockwise) so the camera will record vertically. Instead of cat or person showing on the bottom of the pic, they would be shown in my screen at the left edge of the pic. Advanage: I would use camera frame width (longer dimension) to cover narrow hallway's length. I would utilise most of my frame with usable coverage instead of covering empty hallway walls with horisontal frame of standard setup. Good idea or not? How does it affect my lens choice from the above qustion? I would obviously have to angle camera down manually by slanting the wall as neccessary since camera would not be able to move lens downwards when rotated clockwise 90 deg. Can I place camera normally and rotate 3 mp 4:3 pic for 90 deg in the software? That would be perfect.
 
Unfortunately most camera manufacturers do not specify accurately (or not at all in many cases) the Horizontal (HFOV) and Vertical (VFOV) field of view angles of the camera lens. Both parameters also change per camera depending on the resolution the camera is set (some cameras scale up, some do not). Here is a collection of field of views I have gathered from various sources in the forums. When the field of view angle varies is due to the various sources of information.


​
-------------------3MPixels (2048x1536) ---------- 1920x1080 or 1280x720

Focal Lengh --------HFOV------- VFOV --------------- HFOV ------VFOV

2.8 ------- ----------- 77.6-86 ---62.2 ----------------- 84.3-98----- 54
4 ----------------------58.8-70 --45.8 ------------------64.7-79 -----39.2
6 --------------------- 41.2-43 ---31.5 -----------------45.8-49 -----26.7
12 -------------------- 20-22 ----- 16 ------------------- 3-23.9 ------13.5


So if you want to view a corridor you can rotate the camera and the image by 90 degrees to get a corridor view or in other words in portait orientation and not in landscape orientation which is the most frequently used orientation. You must ensure that the camera has 3 axis rotation ability.
 
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Well, in my experience with a 2.8 mounted in a corner you could see the floor easily enough and people standing at your door up to maybe 6-7 feet away if they were normal height but after that if you want to the hallway you'd lose the floor. If you could mount the camera at 10 foot then you could likely see the whole thing, at 8 foot like a normal ceiling then it will be as I said. Lower will be even worse.

I mount in a corner, not directly above the door so the camera can be angled to cover the door and the room or hallway to the most effect. Like you'd mount a camera in an elevator, so you can catch the most of a small area. If the camera in the corner can be mounted farther from the door, like 3 feet then you'll be able to see the floor by the door easier and maybe still see the hallway, it all depends on your exact mounting location.
 
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These might be helpful for you. Both captured by 2032 bullets with 4mm lenses at 1080p (2MP) resolution:

 
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If you use 2.8mm then you'll get a lot of IR reflection off the walls at night, and end up with a crap image.

4mm rotated and set to 1080p instead of 3MP is better. Why don't you get DS-2CD2322-I ? Or 3022 from @milkisbad if you are US.

Don't bother with 3MP, you don't need or want the extra width on a rotated picture, it will look worse than 2MP widescreen.
 
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Get a fisheye cam. 180 degrees. Problem solved
 
Thanks, here are some very useful tips :) In the meantime, I got factory feedback. They said Hikvision Ds-2cd2132F-IS with 3 MP resolution and 2,8 mm lens had 86 deg Horisontal FOV and for 4 mm lens FOV is 70 deg (I will omit other 2 FOV angles as irelevant for my post). These numbers are the same as written in the brochure for this camera! But, the brochure does not say which FOV angle is quoted (horisontal, vertical, diagonal). So, it would seem they state horisontal FOV in brochures, and we can easily calculate other 2 angles from that (e.g. 86/4*3=64 deg for vertical).

Hmm, how come smaller resolution has larger FOV angle? It is not a crop but seems like it uses wider portion (more actuall pixels) of the sensor than 3 MP frame.

So, now I am considering a Hikvision ds-2cd2142fwd-is which is 4 MP wide sensor. I can not find any FOV for any 4 MP Hik camera. Presuming similarity with 3 MP models, a 4 MP model with 4 mm lens (for me in vertical format) should cover about 80 deg (same FOV as 1920 × 1080 in current 3 MP).

user-offline.png
 
I forgot, nobody commented ony possibilty to rotate the picture. Manual suggests it is possible. So, can I have camera mounted normally (horisontally) but rotate the pic in the firmware of the camera? Which resolution can I get if this is possible. If a sensor is square instead of wide, this would be simple task. This square form of the sensor might be suggested by a larger angle of smaller resolution in 16:9.
 
You can have the camera rotate the picture for you. See my screenshots above. Those are captured directly from the 1080x1920 streams from the Hikvision cameras. The resolution is set to 1920x1080 but after rotation it becomes 1080x1920. Simple as that. If you run them in 3MP mode you get 1536x2048 instead of the usual 2048x1536.
 
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pila said:
Hmm, how come smaller resolution has larger FOV angle? It is not a crop but seems like it uses wider portion (more actuall pixels) of the sensor than 3 MP frame.
Click to expand...

Hikvision's 3MP cameras are a little strange in that their 3MP resolution does not use the full width of the sensor and the 2MP resolution does not use the full height. So if you overlay a 2MP snapshot over a 3MP snapshot you get something like a plus sign shape. + 3MP is taller. 2MP (1080p) is wider.
 
bp2008 said:
You can have the camera rotate the picture for you. See my screenshots above.
Click to expand...
Well, now I understand your previous post :) I am sort of slow :)) This software rotation solves aiming problem for me, so I do not have to mehanically tilt entire camera to get an angle I need.
 
bp2008 said:
You can have the camera rotate the picture for you.
Click to expand...
Another question resulted from that: after I rotate pic to vertical format in camera, do I see this picture as a tiny vertikcall picture on my screen (with most of my scren blacked out left and right of the picture) or do I get full horisontal picture on my screen (but actually showing vertical shot from a camera)? I would prefer this second mode, as I do not mind funny angle, it is more important that the picture is larger. So, I want vertically captured pic to be displayed in its regular horisontal form.
 
pila said:
Well, now I understand your previous post :) I am sort of slow :)) This software rotation solves aiming problem for me, so I do not have to mehanically tilt entire camera to get an angle I need.
Click to expand...

You still have to mechanically tilt the camera. The software rotation just makes the world appear upright again.

pila said:
Another question resulted from that: after I rotate pic to vertical format in camera, do I see this picture as a tiny vertikcall picture on my screen (with most of my scren blacked out left and right of the picture) or do I get full horisontal picture on my screen (but actually showing vertical shot from a camera)? I would prefer this second mode, as I do not mind funny angle, it is more important that the picture is larger. So, I want vertically captured pic to be displayed in its regular horisontal form.
Click to expand...

In some cases, yes. Some video players can stretch the video to fill the screen (though this isn't a very efficient use of space). Or you can turn off the software rotation and see the video on its side but filling more of the screen. Or you can use digital zoom to get more detail when needed. Lots of options are available!
 
bp2008 said:
These might be helpful for you. Both captured by 2032 bullets with 4mm lenses at 1080p (2MP) resolution:

Click to expand...

Hi bp2008. I have recently installed one Hikvision 2342 Turrett along the narrow walk to one side of my detached bungalow and have done exactly what you said, turn the camera 90 deg and then do the rotate function.

I have turned the camera 90 deg and indeed get a nice long view of that path running along my house, also, the rotate option on in camera settings straightens the image for me. Great! But the problem is, in Live View the view is still widescreen and not true portrait. So it stretches the image and looks worse. If i leave the rotate option off, quality is fantastic but i have to turn my head to see it correctly lol.

Is there any way of telling the camera or built-in software to display the image from that camera in TRUE portrait, just like the photos you have uploaded? Or are you using another piece of software to manage the camera? I have a Synology NAS, which I will soon use once I've installed the other 3 cameras.

At the moment, I've just left the rotate function off as although i have to move my head a bit, I find its a nice clear image of the long narrow path.
 
I will never understand why so many cameras draw the video at the wrong aspect ratio in their default interfaces. They don't even fill the screen properly, most of the time. They just draw the video wrong for no reason. I don't know what interface you are using but if it is the camera's web interface then you can probably find a button in the lower left to use the correct aspect ratio.

Myself, I use PC software called Blue Iris to view cameras, and it does not screw up the aspect ratios.
 
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Many thanks for the replies, I'll give blue iris a shot.

I've been using the hikvision cameras built in web interface. In the live view at the bottom it only gives option of 16:9, 4:3, and full stretch
 
Just an update. After playing around so much with all the different built in motion detection technique in the Hikvision cameras for many weeks i have finally installed and bought Blue Iris. So far very impressed as it seems to be very powerful with motion detection. I'm still getting false alerts but I'm slowly fine tuning it by running the recorded video through its motion sensor and re-adjusting settings until false alarm no longer triggered. Hoping this will do the trick.

I am however, looking into physical PIR and connect to the Sealevel unit, which will interface with blue iris. Any recommendations on PIR for the UK market? I was looking at the GJD D Tect 2 or 3 and the Takex PIR-T15WE (W)??

The most challenging camera is the drive way, its set back from a main road, also, lots of sunlight etc and low hedges, so you can imagine...


Thanks
 
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