Various parameters of the camera external reference matrix
The external parameters matrix described how the points in the world coordinate system were transformed into points in the camera coordinate system through translation and rotation. where the index c represents the coordinates in the camera coordinate system, the index w represents the coordinates in the world coordinate system, R represents the rotation matrix, and t represents the translation matrix. The external parameters matrix was actually the alignment of the world coordinate system of a certain point P and the camera coordinate system. That is, after translation and rotation, the two coordinate systems could be completely overlapped. For example, in the rotation transformation in two-dimensional space, a certain point P in different coordinate systems can be represented by the base variables in different coordinate systems.(Among them, xc, yc, xw, and yw are the unit orthonormal base matrices in the coordinate system.) Through these relationships, the meaning of the parameters of the rotation matrix can be obtained: the first column of the rotation matrix represents the direction of the Xw axis in the world coordinate system in the camera coordinate system; the second column of the rotation matrix represents the direction of the Yw axis in the world coordinate system in the camera coordinate system; and so on for the transformation matrix in three-dimensional space. Moreover, when the camera motion is considered, the external parameters matrix will change accordingly based on the initial matrix and each motion matrix (for example, when the camera moves in R1 and t1, the matrix of the motion will be multiplied by the original matrix, etc.). In addition, for the external reference of the non-overlapping field of view camera, one of the calibrations was to construct two similar maps and find all the matching map points. The external reference parameters were the transformation relationship between the maps, which also involved the reflection of the relevant parameters of the external reference matrix in different scenarios. Read more exciting novels for free
External parameters of the camera
The external parameters of the camera were parameters in the world coordinate system, mainly referring to the rotation and translation matrix between the camera systems, such as the position and rotation direction of the camera. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
What are the external parameters of the camera?
The external parameters of the camera were the parameters in the world coordinate system, such as the camera's position, rotation direction, and so on. In terms of specific values, there were six external parameters of the camera, including the rotation parameters of the three axes (<anno data-annotation-id ="00000000 - 4110 - 4445 - 9999 - 9999 - 9999999999999"></anno>,<anno data-annotation-id ="2f0000c8 - 4f08 - 4f10 - 4f08 - 8f001111100000"></anno>). Combining the 3×3 rotation matrices of each axis (first matrix multiplication) to obtain R (size 3×3) that gathered the information of the three rotation axes, as well as the translation parameters of the three axes of T (Ti, Ty, Tz). R and T were combined into a 3×4 matrix, which was the key to converting to the coordinates of the label paper. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Calculating the internal and external parameters of the camera
The internal parameters of the camera included: 1. ** Picture format, size, and quality **: There are two types of photo format: RAW and JPG. You can choose JPG format if you don't need post-processing. If you need post-editing, you can choose RAW format. The daily shooting size can be set to large size, and the picture quality can be set to high quality. However, the size can be adjusted to M or S when shooting news topics and other situations that require fast production. 2. ** White Balance **: Automatic White Balance (AWB) can basically meet the needs of daily shooting. In special scenes or when you want to change the image effect, you can manually control it, such as using the built-in scene mode, manually adjusting the K value, etc. 3. ** Light sensitivity (USB)**: For daily shooting, you can set it to the "STAR"(Automatic Light sensitivity). When you use the manual gear (M), you can manually adjust it to control the image exposure. 4. ** Picture Style **: The camera has a variety of photo styles. It is recommended to choose the "standard" style for daily shooting unless you have special needs or want to try other styles. 5. ** Metering Mode **: Including evaluation measuring (Nikon Matrix Metering, Sony-called Multi-Metering), spot measuring, partial measuring, center-emphasized measuring, etc. The most commonly used is evaluation measuring. 6. ** Focus Mode **: For daily shooting, you usually choose AF-S + single-point autofocus. When shooting moving objects, you choose AF-C + extended focus. 7. ** exposure compensation **: In aperture priority/shutter priority mode, it is usually set to "0EV", but it has to be adjusted according to the "white plus black minus" rule. The external parameters of the camera may involve some indicators related to the camera hardware, such as the sensor (which is the heart of the digital camera), as well as lens-related parameters, but the reference did not mention the lens-related external parameters in detail. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Various camera mode parameters
The common shooting modes of the camera are Aperture priority mode (LV), Shutter priority mode (TV), and Manual mode (M). The parameters of each mode are as follows: ** 1. Aperture priority mode (LV)** 1. ** Aperture setting ** - For landscape shots, the aperture was set to F8 - F11, and the exposure compensation was set to 0. - When shooting a portrait: You can use the maximum aperture or the maximum aperture to reduce the aperture by one gear. At the same time, you can use spot photography to measure the eyes of the model. The exposure compensation is 0. - Cultural street photography: If you need to blur the environment, the aperture is F2.8 or larger; if you don't need to blur the environment, the aperture is F8. - For macro photography, the aperture was between F8 - F11. - [Starlight effect: Aperture: F8 - F11] - For shooting flowers, birds, and insects, the aperture should be at F5.6 or below, and the best was to have an IQ of 400 or less. 2. ** Other related skills ** - Under normal circumstances, unless you want to maintain a safe shutter, avoid using the maximum aperture to shoot. - Try to use F8 - F11 apertures for scenery shots. - For close-ups of characters and still objects, the maximum aperture can be reduced by 1 - 2 apertures. - The safety shutter should be controlled above the inverse of the focal length as much as possible. The wide-angle shutter should be above 1/30s. If the shutter is insufficient, you can increase the aperture or USB. ** 2. Shutter priority mode (TV)** 1. ** Shutter Speed Setting ** - For general body movements, the shutter speed should be above 1/60s. - Walking time: 1/125s or more. - [Fast travel: 1/500s and above.] - Running: 1/1000s or above. - Skiing: 1/2000s or above. - [Bike: 1/2000s and above.] - Normal speed of the car: 1/2000s or above. - [Flight distance: 1/500s] - Follow-up photography: 1/60s- 1/4s - [Freezing birds nearby: 1/4000s] - [Fog Sea: 1/4s or slower] - For daily shooting, the shutter speed is 1/80s- 1/200s. - [Character capture: Shutter speed greater than 1/125s.] - [Baby/Pet: Shutter speed greater than 1/200s.] - Star Chaser/Athlete: Shutter speed greater than 1/1000s. - [Capture car: Shutter speed greater than 1/2000s.] - Starry Sky: 25s-30s. - Shooting fireworks: 3s - 5s. - Light Painting: 15s-30s. - [Star Orbit: More than 2 hours.] ** 3. Manual Mode (M)** 1. ** Different settings for different subjects ** - Full Moon: Shutter speed: 1/500s, Iso200, Aperture: F5.6 - F8 (Clear). - Crescent Moon: Shutter speed: 1/500s, USB: 200, Aperture: F4 - F5.6 (Clear). - New Moon: Shutter speed: 1/500s, USB: 400, Aperture: F4. - [Firework: Shutter speed: 1 - 4s, USB: 200, Aperture: F8.] - [Lightning: Use the B-door, with an IQ of 200 and an aperture of F8 (until the end of the shooting, the environment should be darker).] - Street lights: Shutter speed: 15 seconds, USB: 100, Aperture: F11 (adjusted according to street brightness). - Water boat lights: Shutter speed 30s, USB 100, aperture F8 (adjusted according to the brightness of the environment). - Galaxy: Shutter speed: 30s, 1600 - 6400, Aperture: F2.8 (with super wide angle). - Star Orbit Shooting: Each photo was exposed for 30 seconds, and the next photo was taken at an interval of 1 second. At least 120 photos were taken and stacked later. - Flower photography: Shutter speed: 1/125s, aperture: F2.8, and the CPU is 100 (sunny weather). - Scenery: Shutter speed: 1/125s, aperture: F4, and the CPU: 100 (sunny weather). - Night view: Shutter speed: 1/15s, aperture: F1.8, and the CPU: 200. - Shooting movement: Shutter speed: 1/500s, aperture: F2.4, and the CPU: 100. - Wedding room: Shutter speed: 1/125s, aperture: F2.8 - F8, and the CPU: 400. In addition, the camera's common measuring modes were multiple measuring, center measuring, spot measuring, average measuring, etc. Multi-level Metering is used to calculate the appropriate exposure based on the overall picture, which is basically suitable for most daily shooting. Center Metering is used to take the center of the picture as the important exposure area, which is suitable for shooting with a clear main object in the center of the picture (such as still life, portrait, pet, etc.). Spot Metering only counts the exposure of the picture within the spot, which is suitable for shooting when the light ratio is very large (such as backlit silhouette or black-and-white photo shooting). Average Metering is used to average the exposure information of the whole picture on the screen, which is suitable for outdoor or landscape shooting. Some cameras also had strong light measurement, which focused on the strong light area of the screen to ensure that the part was not exposed. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The relationship between the internal and external parameters of the camera
The internal parameters of the camera mainly included light sensitivity (USB), shutter speed, aperture, AF-ON, depth of field button, M-GN, image confirmation, lens aberration correction, high USB noise reduction, unequipped memory card release shutter, gridline, white balance, color temperature, saturation, etc. These internal parameters affected each other and were also related to external parameters such as the external shooting environment of the camera. The higher the sensitivity value, the brighter the picture, but the higher the value, the lower the quality of the picture and the more noise. The higher the shutter speed, the less light entering, and the lower the brightness of the picture. On the contrary, the higher the light entering, the brighter the picture. However, the shutter speed should not be too low when shooting high-speed moving objects to avoid blurring the picture. The larger the aperture value, the smaller the aperture, the deeper the depth of field, the less light entering, and the darker the picture. On the contrary, the lighter the depth of field, the more light entering, the brighter the picture. AF-ON can be set to switch between single-shot focus, autofocus, and servo-autofocus, which affects the focus mode. The depth of field button can be set to the photo style to choose portrait or landscape shooting. M-GN can be set to drive mode, focus mode, white balance, and light measurement mode. After clicking M-mn, the settings can be switched. Image confirmation can set the time the photo stays on the camera, which is convenient to check the effect of the photo. The sensitivity can be adjusted by setting the minimum and maximum values; the peripheral brightness correction, distortion correction, digital lens optimization and other operations in the lens aberration correction affect the dark angle and distortion of the picture; the high Iso noise reduction can adjust the brightness of the picture in dark environments; the setting of releasing the shutter when the memory card is not installed is related to whether the shutter can be pressed when the memory card is not installed; the grid line can be used as the reference line for composition; The white balance color temperature affected the color of the screen. If it was less than 5200, it would be cold, and if it was greater than 5200, it would be warm. The saturation affected the color of the screen. The external parameters, such as the light intensity of the shooting environment, would affect the settings of the internal parameters. When the light is dim, you may need to increase the sensitivity, reduce the shutter speed, and increase the aperture to ensure enough light. When shooting external situations such as high-speed moving objects (such as sports events), the shutter speed needs to be set higher. When shooting different subjects such as people or scenery (external parameters), you can use the depth of field button to set the photo style to better shoot. Internal parameters such as white balance and saturation needed to be adjusted accordingly to achieve the ideal color effect under different shooting scenes (external parameters). <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to get the internal parameters matrix of the camera
The camera intrinsic parameters matrix can be obtained through camera calibration1. Given the world coordinates and the coordinates of the control points, the process of calculating the world coordinates and the coordinates of the control points was called camera alignment. Once this relationship was solved, the camera's intrinsic parameters matrix could be determined. The internal parameters of the camera were related to the characteristics of the camera itself, such as the focal length of the camera, the size of the camera, etc. The parameters in the internal parameters matrix included the focal length (such as fx and fy in the horizontal and vertical directions), the coordinates of the main point (such as cx and cy), and so on. For example, the internal reference matrix could be expressed as a 3x3 matrix containing these parameters. The real lens may also have factors such as the camera's internal parameters, such as the distortion of the radius and the thickness. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Nikon's various single-lens reflex camera parameters
Nikon single-lens reflex cameras came in several series. The parameters of different series were as follows: - **Dx series **: D1, which started in 1999, was the beginning of this series. The latest product is D6. This series had the strongest focus and continuous shooting performance among Nikon's DSLR, and was the flagship model. - ** D8x series **: This is the flagship image quality camera of Nikon's DSLR. Compared to Canon's 5D series, such as the D850, even after six years of release, the image quality is still very strong. - ** D7x series, D6x series **: They were the entry-level full-frame models of Nikon's DSLR, which were comparable to Canon's 6D series. When the Nikon D600 was released, there was a problem with the shutter assembly. Soon after, Nikon released the D610. The entry-level full-frame D750, which was released in 2014, also belonged to this series. - ** Dx00 series **: This is the Nikon APS-C frame speed flagship camera, which is comparable to Canon's 7D series. It focuses on focusing and continuous shooting speed. - ** D7x00 series **: It was a high-end image quality model with the APS-C format. - ** D5x000 series, D3x00 series **: These are low-end DSLR products from Nikon, and are currently no longer available for sale. For example, the Nikon D810 was a 36-million-resolution full-frame single-lens reflex camera with an aluminum alloy shell. It was priced at more than 20,000 yuan on the market and sold for thousands of yuan second-hand depending on its color. The Nikon D5 and D4S were professional full-frame single-lens reflex cameras, but no detailed comparison of parameters was found. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The parameters of the camera
There were many parameters for the camera lens. The following were some common parameters: 1. ** Focus **: It determines the degree of zooming of the lens. A longer focal length was used for long-distance shooting. For example, a telephoto lens could be used to shoot long-distance topics such as sports competitions, wild animals, aircraft, etc., and it could also enhance the background blurring effect. A shorter focal length was used for wide-angle shooting, such as wide-angle lenses for landscape photography, architectural photography, and crowded indoor spaces. 2. ** Aperture **: For example, the main camera of the Vivo X200 Pro is equipped with a large aperture of f/1.57, which helps to take brighter and clearer photos in dark environments. Its periscope telephoto lens has an aperture of f/2.67, which can ensure the clarity and details of the picture when shooting telephoto. The size of the aperture affected the amount of light entering, depth of field, and so on. 3. ** Pieces **: It is one of the important indicators to measure the quality of the camera. For example, the main camera of the Vivo X200 Pro is expected to use a 50-million-pel large sensor, and the periscope telephoto lens is equipped with a 200-million-pel periscope telephoto lens. 4. ** Photosensor **: For example, the sensor of the HD - 3000 camera is a LCD; the main camera of the Vivo X200 Pro has a 1/1.28-inch sensor, and the periscope telephoto lens has a 1/1.4-inch base. 5. ** View angle **: For example, the helmet camera lens is a 3.7mm pinhole lens with a 90-degree view angle. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The parameters of the camera
The main parameters of the camera lens were as follows: - Aperture: controls the amount of light that enters the lens. The smaller the aperture, the greater the amount of light that enters the lens, and the more obvious the background blurring effect. For example, in a dark environment, a large aperture could allow more light to enter the camera and take a bright photo. At the same time, it could highlight the subject and blur the background. - ** Focus **: determines the angle of view and magnifying power of the lens. The short focal length lens had a wide angle of view and was suitable for shooting large scenes such as landscapes. The long focal length lens had a narrow angle of view and could zoom in on distant objects. It was often used to shoot portraits, close-ups, or sports events that needed to be zoomed in. - ** Shutter Speed **: The length of time the shutter is opened. A fast shutter speed could freeze instantaneous movements, which was suitable for shooting moving objects, such as fast running athletes. A slow shutter speed could capture the trajectory of the object's movement, such as shooting a smooth effect when shooting water. However, a slow shutter speed needed to be used with a tripod to prevent blurring caused by hand shaking. - [Depth-of-field]: It refers to the range of clear images before and after the focal point. A large aperture would cause the depth of field to become shallow, that is, the clear range before and after the focus was small; a small aperture would cause the depth of field to be large, and the clear range before and after the focus would be wide. - ** Light sensitivity (USB)**: It indicates the sensitivity of the camera to light. The higher the value, the more sensitive the camera was to light. In a dim environment, the camera could increase the brightness by raising the value, but an overly high value would cause noise and affect the image quality. - ** White Balance **: Adjusts the camera to ensure that white objects appear white under different lighting conditions. Automatic white balance (AWB) for daily shooting can basically meet the needs, but it can be manually controlled in special scenes or when you want to change the image effect, such as using the built-in scene mode, manually adjusting the K value, etc. - ** Distortion **: Different types of lenses may have different degrees of distortion. For example, wide-angle lenses may produce barrel distortion, and telephoto lenses may produce pincushion-shaped distortion. This was something to take note of when shooting objects that required strict shapes such as buildings. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Internal and external parameters of industrial cameras
The intrinsic parameters of the camera were parameters related to the camera's own characteristics, such as the focal length of the camera, the size of the camera, etc. The intrinsic parameters of the camera were parameters in the world coordinate system, such as the position of the camera, the direction of rotation, etc. The camera was a map between the world coordinates and the pixel-based coordinates. When the world coordinates and the pixel-based coordinates of the control points were known, the map could be calculated. After the calculation, the world coordinates of the control points could be inferred from the pixel-based coordinates, and then subsequent operations such as measurement could be carried out. This kind of calibration-based method was also known as hidden parameters calibration-based method because it did not calculate the internal parameters of the camera (such as the focal length of the camera, the distortion coefficient of the camera, etc.). In the process of image measurement and machine vision applications, in order to determine the relationship between the three-dimensional geometric position of a point on the surface of a spatial object and its corresponding point in the image, a geometric model of the camera image must be established. These geometric model parameters are the camera parameters. Under most conditions, these parameters need to be obtained through experiments and calculations. This solution process is called camera calibration1. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>