Using a night-vision Webcam to monitor 'clear' or 'cloudy'

[SteveBz]

Hi Guys,

Last night I was waiting for the clouds to clear, streaming a webcam from my astro-shed (using 'motion' on a Raspberry Pi), and this is what I got on my phone:

By the time night fell, it was completely dark and I couldn't see the clouds.  If I went outside, however, there were no stars - although it cleared later.

I wondered if anyone has used a night vision webcam for similar application and if it made any difference.  Eg this:

https://www.amazon.co.uk/Generic-Vision-Webcam-12-0Mp-Microphone/dp/B003VY4M42

Apparently you can turn any webcam into a night-vision cam, just by stripping off the IR filter.

I do also collect the sky temp from an mlx90614 chip which works all night long, but it's not as clear and unambiguous as a simple video stream.

Any thoughts?

Regards

Steve

[DaveL59]

The IR on a webcam or cctv won't be up to illuminating the cloud level, best you'd get would be a switch from IRcut to a clear filter if it has on-board IRcut filter and a black&white image. This won't really improve anything tho in terms of sensor sensitivity. Stripping off the IRcut filter (on the back of the lens or off the sensor if it's the fixed type) again won't improve sensitivity very much and also not switch the camera from colour to B&W. It will tho mean daytime images will have an odd colour cast with foliage showing purple, for example. Also if you have any other IR sources like CCTV their IR will interfere with the image if their beam cuts across or onto the camera.

Units that use the Sony IMX (starvis) sensors will do a bit better at low light but the limiting factor is usually exposure times. I've a couple of CCTV modules aimed at the sky and I can get some view of cloud at night so long as there's other skyglow to help, but limited to slow shutter of 1/20s it's not the best but does show the brightest stars. I have considered modifying a Logi C270 and running that via Sharpcap where you seem to be able to run slower shutter but this far I've not tried as I may need it for other things like remove interviews 🙂 

A sky-cam using an astro camera would normally use a much longer exposure to achieve starfield capture but then you need to handle sensor temps to cut down on noise.

edit - on the camera linked, I'd be real iffy about an ad that claims 12MP and then says its a 640x480 sensor, makes you wonder what else they aren't telling truths about

Edited August 23, 2020 by DaveL59

[SteveBz]

1) Yes, I saw the Starvis range.  I was looking for a webcam with the IMX290.  You can buy the mounted chip on a board for CCTV for less than 20 quid, but the ZWO ASI290 is in excess of 250.  The problem is that the board comes with video scanning chip, so you'd need to somehow convert the video PAL or whatever to USB.

2) There were numerous typos, but I missed the

37 minutes ago, DaveL59 said:

ad that claims 12MP and then says its a 640x480 sensor

Well spotted.

3) Finally, do you think it's just illumination and not IR sensitivity?  I didn't think of that.  Maybe you're right.

37 minutes ago, DaveL59 said:

The IR on a webcam or cctv won't be up to illuminating the cloud level

I could actually see the clouds at night through my guide-cam.  Maybe I could stream that in a similar way.

Regards

Steve.

Edited August 23, 2020 by SteveBz

[Bruce Leeroy]

You might get a slightly better result using a PS3 eye camera, in windows using the drivers supplied with CL-Eye-Test.exe I can get a 10 second exposure, these cams where available for 50p in CEX but the price has gone up to £2.50 last time I checked. I have 1 in my shed pointing down the garden and if Saturn/Jupiter are over my roof it picks them up and I can see clouds, there is a prefered model with a good lens if your going to remove the ir filter (i mention this as the bad model seems to have a solid pink lower right corner when you set a long exposure).

In the next few days I will point it up at the clouds and post a pic here if it helps.

Just checked, the price has gone up to £3.

https://uk.webuy.com/product-detail/?id=SPSEYEE001&sku=SPSEYEE001#.WZgRyMaQyUk

[DaveL59]

33 minutes ago, Bruce Leeroy said:

You might get a slightly better result using a PS3 eye camera, in windows using the drivers supplied with CL-Eye-Test.exe I can get a 10 second exposure, these cams where available for 50p in CEX but the price has gone up to £2.50 last time I checked. I have 1 in my shed pointing down the garden and if Saturn/Jupiter are over my roof it picks them up and I can see clouds, there is a prefered model with a good lens if your going to remove the ir filter (i mention this as the bad model seems to have a solid pink lower right corner when you set a long exposure).

In the next few days I will point it up at the clouds and post a pic here if it helps.

Just checked, the price has gone up to £3.

https://uk.webuy.com/product-detail/?id=SPSEYEE001&sku=SPSEYEE001#.WZgRyMaQyUk

handy to know and a bargain price, what are the specs for resolution? I assume it's USB connected, wonder if sharpcap would pick it up.

edit - ah ok, looks to be 640x480, pity as I think that's a bit low-res for a good view with a 150 degree lens

Edited August 23, 2020 by DaveL59

[pete_l]

1 hour ago, SteveBz said:

1) Yes, I saw the Starvis range.  I was looking for a webcam with the IMX290.  You can buy the mounted chip on a board for CCTV for less than 20 quid, but the ZWO ASI290 is in excess of 250.  The problem is that the board comes with video scanning chip, so you'd need to somehow convert the video PAL or whatever to USB.

I have used IP cameras (they send a video stream across an internet connection) with both IMX291 and IMX335 sensors. I find the IMX291 (1920x1024) unsuitable due to the wide+narrow format. It is a poor match for a lens that projects a circular image. However the IMX335 has a 4:3 format and a chip size that is a good match for many M16 lenses.

Ordinary fisheye lenses have absolutely tiny apertures so there are very few stars bright enough to register. However, there are some lenses available that work at F/0.95 (yes! less that a unity focal ratio). These are pretty good at gathering starlight, although they don't provide coverage of the entire sky.

 

At present I am using a 4mm FL lens of dubious quality and unknown focal ratio. That gives a 70°x50° view (plate solved example here) and when I stack 100 subs, there is a decent level of sensitivity. Although as you can see, there is considerable distortion on bright stars.

Edited August 23, 2020 by pete_l

[Bruce Leeroy]

7 minutes ago, DaveL59 said:

wonder if sharpcap would pick it up

Works fine in Sharpcap, the resolution is fine for checking cloud cover I imagine but yes it's not exactly high res . If you search Ps3 eye in SGL there's a fair amount of discussion on them. There also good for motion capture/head tracking using high frame rates this is where removal of the ir filter has it's advantages.

[DaveL59]

34 minutes ago, pete_l said:

I have used IP cameras (they send a video stream across an internet connection) with both IMX291 and IMX335 sensors. I find the IMX291 (1920x1024) unsuitable due to the wide+narrow format. It is a poor match for a lens that projects a circular image. However the IMX335 has a 4:3 format and a chip size that is a good match for many M16 lenses.

Ordinary fisheye lenses have absolutely tiny apertures so there are very few stars bright enough to register. However, there are some lenses available that work at F/0.95 (yes! less that a unity focal ratio). These are pretty good at gathering starlight, although they don't provide coverage of the entire sky.

 

At present I am using a 4mm FL lens of dubious quality and unknown focal ratio. That gives a 70°x50° view (plate solved example here) and when I stack 100 subs, there is a decent level of sensitivity. Although as you can see, there is considerable distortion on bright stars.

Agree Pete, is very hard to find a good lens for the 1080P format sensor. I'm using M12 and CS lenses but you have a view that is clipped top & bottom for what is available at sensible prices. Not so much of an issue here tho given it'd be picking up neighbouring houses. I've purchased "fast" starlight lens versions and they do help in terms of light throughput but the small aperture limits things along with the lack of slow shutter of the module. Not tried any unity lenses tho.

[SteveBz]

1 hour ago, pete_l said:

I have used IP cameras (they send a video stream across an internet connection) with both IMX291 and IMX335 sensors. I find the IMX291 (1920x1024) unsuitable due to the wide+narrow format. It is a poor match for a lens that projects a circular image. However the IMX335 has a 4:3 format and a chip size that is a good match for many M16 lenses.

Ordinary fisheye lenses have absolutely tiny apertures so there are very few stars bright enough to register. However, there are some lenses available that work at F/0.95 (yes! less that a unity focal ratio). These are pretty good at gathering starlight, although they don't provide coverage of the entire sky.

At present I am using a 4mm FL lens of dubious quality and unknown focal ratio. That gives a 70°x50° view (plate solved example here) and when I stack 100 subs, there is a decent level of sensitivity. Although as you can see, there is considerable distortion on bright stars.

I'm only looking to see if it's worth stopping what I'm doing and set up guiding/focusing and want to be able to stream so I can pick it up on my phone.

In the example you show (which looks great by the way).  I guess you're streaming at, say 50 fps, and then stacking live to produce a new frame every minute and a half.  Is that how it is?  The solving is icing on the cake. 

Regards

Steve.

[SteveBz]

2 hours ago, Bruce Leeroy said:

I have 1 in my shed pointing down the garden and if Saturn/Jupiter are over my roof it picks them up and I can see clouds, there is a prefered model with a good lens if your going to remove the ir filter (i mention this as the bad model seems to have a solid pink lower right corner when you set a long exposure).

In the next few days I will point it up at the clouds and post a pic here if it helps.

Amazing.  3 pounds? Less than a drink.

Can you see clouds at night?  What about, say Vega or the other bright stars?

Regards,

Steve.

[SteveBz]

2 hours ago, DaveL59 said:

ah ok, looks to be 640x480, pity as I think that's a bit low-res for a good view with a 150 degree lens

Honestly, I just need an indicator that says get up/don't get up. On a clear summer night, I'm just looking to see if Arcturus or Vega is visible.  If they are I'm on it.

[pete_l]

24 minutes ago, SteveBz said:

In the example you show (which looks great by the way).  I guess you're streaming at, say 50 fps, and then stacking live to produce a new frame every minute and a half.  Is that how it is?  The solving is icing on the cake.

I have the camera's control panel set to 10 FPS with a max. exposure time of 80mS (as high as it will permit).

I am using opencv + python to grab 5 MPix images off the stream and save them as PNG format stills. After I have collected a batch, which usually takes about 12-13 seconds then I numerically add them. The result is gamma adjusted and sharpened a little to produce the final result.
If someone has an alignment algo in python then I'd be interested to see it

Edited August 23, 2020 by pete_l

[SteveBz]

9 minutes ago, pete_l said:

I have the camera's control panel set to 10 FPS with a max. exposure time of 80mS (as high as it will permit).

I am using opencv + python to grab 5 MPix images off the stream and save them as PNG format stills. After I have collected a batch, which usually takes about 12-13 seconds then I numerically add them. The result is gamma adjusted and sharpened a little to produce the final result.
If someone has an alignment algo in python then I'd be interested to see it

I do, it's also in opencv.  I'll send see if I can find it.  I stopped using it in the end because it was only 8-bit and I wanted better colour depth.  Hang on while I look.

[SteveBz]

1 hour ago, pete_l said:

I have the camera's control panel set to 10 FPS with a max. exposure time of 80mS (as high as it will permit).

I am using opencv + python to grab 5 MPix images off the stream and save them as PNG format stills. After I have collected a batch, which usually takes about 12-13 seconds then I numerically add them. The result is gamma adjusted and sharpened a little to produce the final result.
If someone has an alignment algo in python then I'd be interested to see it

Here's a bit of code.  I doubt it still works.  As I recall it only used .jpgs, but you'll see the key words in it like these ones:
 

warp_mode_dct = {
    'Translation' : cv2.MOTION_TRANSLATION,
    'Affine' : cv2.MOTION_AFFINE,
    'Euclidean' : cv2.MOTION_EUCLIDEAN,
    'Homography' : cv2.MOTION_HOMOGRAPHY
}

I got it from a tutorial on the web about restoring some 19th century photos of a pre-revolutionary Mogul or Cossack patriarch. Here:

https://www.learnopencv.com/image-alignment-ecc-in-opencv-c-python/

Good luck.

I managed to stack an image of Orion on it before I moved to raw images.

Regards,

Steve.

stack.py

Edited August 23, 2020 by SteveBz
Update URL

[SteveBz]

6 hours ago, SteveBz said:

 

Last night I was waiting for the clouds to clear, streaming a webcam from my astro-shed (using 'motion' on a Raspberry Pi), and this is what I got on my phone:

 

I Forgot to say, after it got dark, I could see this, through my guidescope:

Not very wonderful, but as it was moving, it was clearly clouds.  If I could stream, say every 1 or 2 seconds, I could also get the right answer.

S.