Polarization Control with Optics - polarisation state

 2024-08-12 11:37:19

Camera sensordetector

Truman, Dahua devices right now are in the middle of a global hack attack (e.g., 1). It is just the latest in an almost never ending string of problems Dahua has.

They're counter suggestions were H.264 Axis cameras, which I wouldn't be surprised if they were better. I'd bet everyone here knows more than I do across the board of surveillance - and would only have some trouble if I could choose very specific subjects from which to debate knowledge.

The project was just approved yesterday with Dahua cameras. This is a HOA, and there is nothing critical on the network. They do not care. I think it is important to realize some customers are not concerned and that is primarily based on the client type/size.

For instance, a device* that claims 4k 30fps might only be able to do so with WDR off, a certain CODEC, no motion detection, no substreams and when connected to its own brand recorder.

Historically speaking, CCD-based sensors have had a lower noise level, a higher single-shot dynamic range, a more uniform response to light across the entire sensor, and greater sensitivity in low light due to a higher pixel fill factor. On the other hand, CMOS sensors have been capable of much higher frame-capture rates, lower power consumption, higher responsivity, and were less expensive at volume [1]. This led to CMOS sensors being preferred in low-cost/low-power applications such as smartphone and other consumer cameras, and in cases where high frame-capture rates are needed. CCD cameras have had performance advantages in cases where high sensitivity, low noise, and/or high uniformity are needed, such as certain low-light applications.

As you said, yeah, it's possible they think the rest of the planet's people will not care as much as one continent does - and thus, have two manufacturing processes as though THAT would be a cost savings.

You have already made it clear in the previous discussion that you are 100% committed to Dahua (e.g.,Looking For NVR To Record UHD Cameras And Work With A NAS) despite our concerns already expressed.

IPVM is the world's authority on physical security technology, profiled by Time, The Atlantic, Wired and collaborated with the BBC, NY Times, Reuters, WaPo, WSJ, and more.

What is a camera image sensorused for

Intel's system (at least years ago) to differentiate the clock speeds was based on impedance, corresponding heats at higher speeds, which compelled them to impose a clock cycle for the CPU in question based on it's performance, in the variations of manufacturing.

Image sensorexample

In monochromatic cameras, the image is obtained simply by recording the amount of light captured by each pixel. In most colour cameras, an array of red, green and blue (RGB) colour filters (a Bayer filter) is placed over the pixels that restricts the light collected by each pixel to a certain range of wavelengths (colours)[1]. Based on the amount of light collected by each of the filtered pixels, the colour image is inferred based on the collected pattern, in a process called demosaicing [3].

The "undisclosed manufacture" above seems biased; he's literally pretending the term AT doesn't connect the two specifications to one another.

I'll happily install a product that I've had no issues with (for example, Dahua), in the past 3 years. Heck, I've even got Dahua installed at home (along with Mobotix). So yeah, why not?

Hikvision 4k basic models... ...and had someone mention Milestone ... which seems very very interesting. I have a NAS which supports iSCSI, so I might try out the free version but I think I have to ultimately get a paid version because I want more than 8 cameras.

Many cameras in the security industry offer variable frame rates based on the resolution choice or sometimes other features.

It must be noted that the quality of CMOS sensors has developed rapidly over the last few years and the advantages in performance that CCDs have had historically are diminishing. Some CCDs still have advantages in dynamic range, uniformity, and IR performance and are preferred for some scientific and industrial applications [2]. Nonetheless, CMOS-based detectors are available that are suitable for most applications, in addition to those for which they have been historically preferred. Ultimately the required specifications and cost of the sensor are what must be considered.

What is a camera image sensorapp

And if not Dahua.... I want H.265+ (plus is showing HUGE improvements of efficiency in my testing so far), 4k (PPF... this is what's good for me), and 30 FPS is my hope. MAYBE 25 is okay... but I'd prefer 60! :)

In cases where colour images are needed along with the advantages of a monochromatic sensor, alternative methods can be used. One method is to take individual red, green and blue images with a monochromatic camera using full-frame colour filters, and to reconstruct the true colours by combing the three images. Another method is capture RGB images simultaneously using three sensors with a special prism used to direct each colour range to one of the three sensors (sometimes called a 3CDD camera [5], though CMOS sensors could also be used).

Earlier, I had stated the industry had for some time, several vague concepts including the simple difference between IPS and FPS or measuring light requirements with LUX or Lumens.

Types ofcamera sensorsize

Selecting and using a camera sensor in a medical device requires the consideration of many factors. In this blog series, we have discussed some of the most important aspects such as resolution, pixel size, dynamic range, exposure time, and frame rate, as well as the most common types of image sensors and their advantages and disadvantages. With proper attention to these factors, a camera sensor can be chosen and configured to produce the most high-fidelity images and/or cleanest data possible.

I have to agree with Jay, primarily because typically when I install any product it has been selected based on what I am protecting. Would I install Dahua in a high risk, asset location? HECK NO! Would I install Dahua at a local HOA sure, why not? Of course, I'll take the necessary precautions (as standard procedure when using Dahua).

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I was at a board meeting last week and they asked, what brand of cameras are we selling. I told them Dahua, even spelled it out nice and slow. For the first time ever, I got feed back on the hack. They googled the camera and read about the hacks. My contact told me he talked to the person with the concern and squashed their concern. I advised him we change all the default ports, and passwords. I also offered him a VPN solution, which he denied.

My reference to HK was Hong Kong as I read a few statements about your desire to buy from outside the US in your other post.

Yes, I'll bet that scenarios exist which pose problems for the engine, gets hot, slacks off, resumes again -- after all, H.265 is even hard for the $2500 laptop I use. BUT, these cameras have the "luxury" of specificity, instead of generalized demands for performance, which must be hard on computers.

CMOSimage sensorworking principle

Both CCD and CMOS sensors come in colour and monochromatic (also called “black and white” though the sensors actually produce images in greyscale) varieties.

X-ray images can be captured using digital radiography sensors. The most common type of such sensors are flat-panel detectors (FPDs) [6]. These detectors come in “direct” and “indirect” varieties. Similarly to conventional image detectors, direct FPDs convert X-ray light directly to charge (but use different materials), and the generated charge is read out by a pixel array. Indirect FPDs first use a scintillator to convert the incident X-rays to visible light, which is then measured by a pixel array.

Thermal cameras measure infrared (IR) light and use it to infer temperature. A number of technologies exist for making such cameras. One example is a microbolometer array, which consists of an array of specialized pixels. The top layer of these pixels is a material that changes resistance when heated by IR light. The change in resistance is then measured by underlying electronics to infer temperature. The array of pixels then generates a thermal image, showing the spatially-resolved temperature of the imaged object.

That was a problem in marketing and it was addressed by IPVM in the early years if you read back on Arecont and Avigilon. Most manufacturers seem to be more clear now.

Ryan Field is an Optical Engineer at StarFish Medical. Ryan holds a PhD in Physics from the University of Toronto. As a post doctoral fellow, he worked on the development of high-power picosecond infrared laser systems for surgical applications as well as a spectrometer from home materials.

All of those are true, just not st the same time. Marketing at its finest and still out there a bit. My experience with Dahua 4K cameras is 20FPS in 4K mode, 30FPS in lower resolutions.

How doesa camera sensorwork

[1] Each pixel on a colour image sensor has either a red, green, or blue colour filter, which is different than the way colour is handled by the pixels on a typical monitor. Each individual pixel on a monitor has a combination of red, green, and blue subpixels.

In CCDs, an array of photosensitive capacitive sites (i.e., pixels) each accumulate charge proportional to light incident upon them. After the exposure to light has been completed, a control circuit is used to move the charge from each pixel into a charge amplifier, which converts the accumulated charge into a voltage. Once the charge collected on each site has been measured, an image can be generated.

IF he has proof they're lying, PROVIDE IT. But alleging it without proof is dishonorable unless he can provide the evidence to support it.

I searched the US site, not HK and see the 12MP at 20IPS and 4K at 30IPS. 4K is UHD so I wonder if the HK version is the same. You don't need 12MP for UHD.

Philosophy urges us all to defend against self deception; confirmation bias. Hypocrisy (you'd be pissed if someone critiqued your product and without proof... and I'd be grateful to anyone who studied my product enough to find the problems with it! This is expensive stuff to do.

However, mfr#2 is not making a claim himself, but rather relaying a statement from Dahua, and so has no burden of proof, except that in regards to correctly echoing the statement, if so challenged.

Camera sensortypes

Colour camera sensors are useful because they provide a simple way to capture colour images. They can also be used to approximate a monochromatic camera sensor in software (for example, by only displaying data from the green channel, or by converting a captured image to greyscale). However, they have some disadvantages compared to monochromatic cameras, which are often the superior choice when colour is not needed.

Finally, it is possible to generate an image of an object without using a pixel array-based sensor at all. Single-pixel cameras are a type of “camera” that operate by measuring (with a single photodiode, for example) the amount of light reflected from each of a series of patterns projected on the object. In the most straightforward case, the pattern is simply a focused point of light that is scanned over the surface of the object. By mapping the amount of reflected light to the location from which it was reflected, an image of the object can be inferred.

Truman, let me make clear, if I haven't yet, that your expectation that the Dahua spec "UHD @ 30FPS", is a truth-bearer, is also one shared by myself.

This blog is the third in a series discussing things to consider when choosing a sensor for a medical device camera. The first entry in this blog series covered camera sensor resolution and pixel size. The second entry covered considerations related to incident irradiance, exposure time, gain, and frame rate, and their impact on figures of merit such as dynamic range and signal-to-noise ratio.

I'd bet you're bereft of a scintilla of specific knowledge of this Dahua model (*81230*) or any with that root identifier in it.

On the other hand, maybe you don't care about substreams etc, all you need is 4k 30fps, so it's important to find out the subjective motivation for the statement.

To which, this member said that it doesn't "really" do that. Wait, what? This is a finite, mathematically expressed statement. It either does or doesn't, and math is the only truthful, finite language devoid of ambiguity.

Dahua asserts directly by use of the @ symbol, that those two specifications are Dahua's direct claim of the frames per second and the resolution it'd be transmitted at. I bet they even tested this.

To make sure people can't waste your life with absurd claims, science has adopted a principle; the person MAKING the claim - assumes the burden of justifying it. You sir, have adopted the burden of proof!

In my discussion of products I'm getting, I mentioned (in a thread) that I wanted units which did 4k at 30FPS. These are H.265+ cameras, which have a MAX bit rate of 10Mb... and a single (healthy) 3.5" hard drive does 150+ MB/s...

I GET that WDR is subject to spurious claims which contain subjectivism; but a resolution is counted numerically; and the number of frames which can have different pixel content is numeric. These are finite, clear commitments.

What I read from the Dahua US site was shown and clearly stated that they offer 12MP/20 or 4K/30. 4K is considered UHD in this industry.

Or it might deliver the 30 frames in a second, but those frames may come in juttery spurts, causing the video to appear choppy.

In CMOS sensors, each individual pixel contains a photodetector (usually a photodiode – i.e., a diode that generates current when light is incident upon it) with a circuit containing a number of transistors. The circuit controls the pixel’s functions such as activating or resetting the pixel, or reading its signal out to an analog-to-digital converter.

But Dahua's statements seem like one's that lend themselves to epistemic claims. How is this errant? I DON'T, get it. What can I trust if not numbers that are expressions of unambiguous, discrete events?

Each of the individual pixels on a colour sensor does not receive the full RGB information. This fact, along with the demosaicing process, results in an image whose effective resolution is slightly less than that of a monochromatic camera with the same size and pixel count [4]. Monochromatic cameras also have higher a greater response to a given incident irradiance than colour cameras, as none of the light incident on the pixels is filtered out.

Dahua's track record shows that you are risking hitting all types of problems and headaches using them. The professionals, e.g., who buy premium priced products are not all stupid, there is a reason why people pay a premium for what you consider inferior technology and that is because those competitors have a much better track record of delivering what they claim and not subjecting their customers to future problems.

Most images sensors are either charge-coupled devices (CCD) or complementary metal-oxide semiconductor (CMOS) arrays. These sensors operate using different electrical mechanisms and are fabricated by different methods, and as such they tend to each have their own advantages and disadvantages.