An active system means that the system itself generates energy - in this case, light - to measure things on the ground. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. 30m for Landsat 7, referring to an area of 30mx30m on the ground (Figure 1). The angle of view is the visible extent of the scene captured by the image sensor, stated as an angle. 1:100,000), and those with larger ratios (e.g. [>>>] Instantaneous Field of View. Feel free to disagree with me in the comments, Im absolutely open to other suggestions if they can be backed up with some source of information. His editorial work has been featured in publications all over the world, and his commercial clients include brands such as Nike, Apple, Adobe and Red Bull. If you stood a car vertically up on its end and asked someone how long the car is, they would tell you the distance between the front and rear bumper. How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? Most would be alarmed to know that they don't have sufficient capabilities to measure such components. A sensor on board the U.S. NOAA (National Oceanographic and Atmospheric Administration) series of satellites with exactly these types of characteristics is actually used for this type of monitoring over the entire surface of the Earth! I read that radio telescopes have huge fields of view (FoV), but are unable to precisely localized objects due to their small instantaneous field of view (IFoV). In my opinion, the FOV changes with respect to its sensor size of the camera. IFOV Calculator. The exact size and orientation is proprietary to each manufacturer and to each model and is not always published. Nor is most of the math except for the really bored. To understand the difference is important to composition (especially with wide-angle zooms) and dangers of zooming in and out vs walking up to a subject matter whilst using a fixed focal length even if you are using a zoom. Which of the two images is of a smaller scale? Sun is the source of optical remote sensing. Changing the focal length changes the angle of view. I hope Im not adding to the confusion already. 1. Scale The image scale or map scale as it is sometime called refers to the relative difference in size eg The Canon 35mm lens has an angular field of view of 54.4 degrees and a linear field of view of 103ft at 1000yds. Cameras use a combination of multiple pixels to obtain a single measurement. Passive microwave sensing Passive microwave sensing is similar in concept to thermal remote sensing. Because the AOV that manufacturers identify for a lens directly relates to the size of the sensor, using the crop factor works well when determining AOV when working with other sensor sizes. Method 1: IFOV=Detector Element Size/Camera Focal Length, Method 2: The second method IFOV=FOV/number of pixels in the direction of the FOV multiplied by [(3.14/180)(1,000)], where multiplying by [3.14/180)(1,000)] converts to mRad. The creation of an accurately classified point cloud usually requires tremendous input from manual annotation. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation . Use Band Ratios to enhance the spectral differences between bands and to reduce the effects of topography. Hi, your angle of view calculation is surely for horizontal angle of view, whereas (as in your early quotes in the article) it usually refers to the diagonal angle of view. A Review of the Terminologies Used and its Interpretation. I would suggest stretching the left side of the diagram to be longer. I truly and greatly appreciate the information provided here both in the article and the comments. On the 85mm you see more of the front of the shoe. Nikon agrees with Sony here, although they do then go completely rogue and start talking about picture angle in a section labelled angle of view which is a term never mentioned anywhere else by anyone else, and, in my opinionis probably just the result of a poor translation at some point. Torsion-free virtually free-by-cyclic groups, Partner is not responding when their writing is needed in European project application. Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. You will not receive a reply. Diagonal is usually used because it is meaningful whatever the aspect ratio of the sensor/image e.g., 4:3, 3:2, 16:9 which are nowadays often settable in-camera. I was trying to appeal to the 1970s energy thing, and still suggest how one understood exposing film and paper. Applications of super-mathematics to non-super mathematics. See Multispectral Scanner for sample usage. The IFOV and the distance from the target determines the spatial resolution. LiDAR is an active remote sensing system. It is important that thermographers clearly understand their spot measurement size prior to imaging a target, otherwise they may significantly misstate a temperature without having a sufficient spot size for the target. Spatial Resolution. Field of view describes the scene on the camera sensor. Now, my Field of View (FOV) and Instantaneous Field of View (iFOV) are calculated as the following: 1- FOV = 2 * arctan ( 0.5 * sensor width / focal length ) = 18.18 degrees An FOM which combines minimal loss of object space contrast and detection of small radiance changes is the ratio of MTF at IGFOV to noise-equivalent radiance at a defined reference radiance level. I also think that people who are going to bother to read this article will have enough common sense to make the switch in width and height if they are calculating this in order to know how much horizontal view they will capture with the camera in the vertical orientation. Thanks again! Be sure to use the FOV for the X direction and the pixel elements value for the X direction to get the appropriate IFOV in the X direction. Other aspects can be found in: Joseph, G. (2020) How to Specify an Electro-optical Earth Observation Camera? What is the difference between IFOV and FOV in remote sensing? For enquiries,contact us. Professional photographer based in Yukon, Canada, and founder of Shutter Muse. The large east-to-west expanse would be best covered by a sensor with a wide swath and broad coverage. On a wide Angle lens the angle of view remains the same but your field of view will change as you move closer or farther from the subject. Commercial satellites provide imagery with resolutions varying from a few metres to several kilometres. Angle of View Vs. Field of View. At the minimum focal length of 0.1m, 1 pixel would see an area 0.17mm square (0.106mm with SR). Only these parameters known. Your head is aligned so that the center point of the window is aligned with the center point between your eyes. The manufacturers specification of spatial resolution alone does not reveal the ability of an EO sensor to identify the smallest object in image products. However, it is possible to display an image with a pixel size different than the resolution. At the sensor, it is represented as the noise-equivalent radiance change (NEL). The image enhances the spectral differences between bands. It is important to remember that angle of view is entirely determined by both the focal length of the lens and the format of the cameras sensor, so the angle of view you get from any given lens will be different on 35mm full-frame and APS-C format cameras. difference between ifov and fov in remote sensing / April 27, 2022 / apptweak similar apps April 27, 2022 / apptweak similar apps They are typically thought of as square, so is size the area? The IFOV is commonly expressed in milliradians. Skip this step and head to the download directly. The angle of view is affected by both the focal length of the lens, and the size of the sensor in the camera. Note: The iFOV is the angle subtended by the detector element (one pixel). Your field of view widened so you can see more but your angle of view basically stayed the same. Simply comparing lens angles and detector sizes is not sufficient to determine exactly what a camera can measure at a given distance. But i can say, from year 2018 beginning, i started noticing AOV of the lenses in its specification, especially when i looked into buying higher focal length. Thank you! 135mm is my favorite portrait lens because the angle of view give a more realist and flattering reproduction of what I saw when I took the picture. It only takes a minute to sign up. The information in the IFOV is represented by a pixel. with an instantaneous FOV (IFOV) of Table 1. . This button displays the currently selected search type. Compare what an astronaut onboard the space shuttle sees of the Earth to what you can see from an airplane. There is a lot of confusion when it comes to the specifications that describe a thermal imager's measurement capabilities. Thanks for contributing an answer to Physics Stack Exchange! Defined as the angle subtended by a single detector element on the axis of the optical system. What is the difference between field of view and field of regard? Thats useful. They can observe for wavelength extend from 400-2000 nm. In the simplest case of a single-element lens, AOV is dependent on the focal length alone. A lens doesnt change its angle of view when you rotate the camera . How do you use swath? FOV refers to the scene to be captured which infers focus a specific distance from the camera, consequently FOV has as a component the distance to the plane of focus. Radiometric resolution is often confused with the number of quantization bits. Nadir : The point on the Earths surface directly below the satellite. Consider having a diagram just for AOV. Spatial Resolution. It is quoted in. This brings us to the topic of discussion of interpretation and analysis. Even though that might technically be considered its height at that point. One is to mount the telescope and associated transceiver optics on a scanning mount. Gura Gear Kiboko City Commuter 18L The Perfect Camera Bag Found? Apr 2015. So, the spatial resolution of 20m for SPOT HRV means that each CCD element collects radiance from a ground area of 20mx20m. During postprocessing this may be resampled to 5m resulting in five pixels over 25m. If looking at a lens irregardless of sensor or film, the correct term for what the lens can transmit is angle of coverage a term that large format photographers have to use when describing a lens capabilities unrelated to the back plane. Thats a nice way to define the differences. Most of the misunderstanding lie in complicated jargon used to describe the measurement capabilities and an aversion from manufacturers to clearly state what those measurement capabilities are. Naif Alsalem. A second diagram for FOV would be a duplicate of the AOV diagram with the Field of view (or Linear field of view if you must) caption referencing dimensions (rather than distance) included and caption Angular field of view in front of the image plane. You have explained these concepts much better than my university profs :/ Although, the equation that I was given for angle of view actually incorporates the pixel size {AOV = 2*arctan((sensor width/2*pixel size)/focal length)} any ideas where the differences may stem from? You take a step closer to the window. For them, spatial resolution refers to identifying adjacent objects with different reflectance/emittance in the scene. While this might simplify the calculation to a general rule of thumb, I have noted that this factor does not hold true for all FLIR models. In their article it states that AOV is a property of the lens and does not change no matter what size of sensor is in the camera, whilst FOV is a function of the lens AND the sensor size. Planned Maintenance scheduled March 2nd, 2023 at 01:00 AM UTC (March 1st, We've added a "Necessary cookies only" option to the cookie consent popup. If one was familiar with specifications for binoculars or rifle scopes one would find this familiar. Maps or images with small "map-to-ground ratios" are referred to as small scale (e.g. 423 mm (W) by 238 mm (H)]. And the reason camera manufacturers do it is not necessarily as nefarious as it may appear. How much do you have to change something to avoid copyright. The images may be analog or digital. The higher the radiometric resolution, the more sensitive a sensor is to detect small differences in the reflected or emitted energy. aperture 4, F-stop f/4, exposure time 1/100 sec. FOV (Field of View): This is the maximum angle at which an electromagnetic sensor can detect electromagnetic radiation. What clues did you use to determine this? For more info check our privacy policy. There are two kinds of observation methods using optical . An incorrect spot measurement size (ie being larger than the target being imaged) will typically understate the temperature if the target is hotter than the background, as the imager will average both the target and background temperatures. rev2023.3.1.43269. The detail discernible in an image is dependent on the spatial resolution of the sensor and refers to the size of the smallest possible feature that can be detected. Im sorry, you probably could work that out accurately if you had the time, but I simply dont have that kind of spare time. Whats the difference between contact discontinuity and shock discontinuity? I have come across it when I was confused about different interpretations/uses of the Field of View/Angle of View/Instantaneous Field of View etc. The linear array is made up of a number of detectors, which are optically isolated (Figure 2). You can imagine light quickly strobing from a laser light source. The terms "scale" and "resolution" are often used in remote sensing discussions and it is important to know what they mean and how they differ. They just have to follow the diagram. In this article, focusing on spatial resolution and manufacturers specifications, the author issues a wake-up call to users encouraging them to better understand the abilities of EO sensors for object recognition and provides a means to compare their performance. I have one question. This is not true (Joseph, 2020). The field of view (FOV) is the angular cone perceivable by the sensor at a particular time instant. Here you can find tables of common angles of view for a variety of focal lengthsand a little more about the math. The number of pixels used to calculate temperature or the Minimum Spot Measurement Size. 18 mm), the wider the angle of view and the greater the area captured. difference between ifov and fov. Cheers, To explain spatial resolution, the configuration of a pushbroom imaging sensor consisting of a linear array is considered. For Optris IR cameras, depending on the lens, this ranges from 4 (telephoto lens) to 90 (wide angle lens). So, the spatial resolution of 20m for SPOT HRV means that each CCD element collects radiance from a ground area of 20mx20m. 144 mm (W) by 108 mm (H)], Camera focal length 35 mm, lens focal length 9 mm, max. The focal length f of the objective. Required fields are marked*. If you know the focal length, and the distance to subject, you can calculate the angle of view and then the field of view. Thermal remote sensing in the framework of the SEN2FLEX project: field measurements, airborne data and applications . The firm recently tested its innovative NavVis and PointFuse We encourage you to subscribe to our weekly newsletter. The IFOV is the angular cone of visibility of the sensor (A) and determines the area on the Earth's surface which is "seen" from a given altitude at one particular moment in time (B). Now as you stand there someone cut out the window leaving a hole . There are two kinds of observation methods using optical . However, fine detail would not really be necessary for monitoring a broad class including all vegetation cover. In terms of a digital camera, the FOV refers to the projection of the image on to the camera's detector array, which also depends on the camera lens' focal length. Remote Sensing 11 Ayman F. Habib Remote Sensing 12 Ayman F. Habib fSpatial Resolution In above case what is FOV (in distance and in angle) of original and stitched image? The IFOV characterizes the sensor, irrespective of the altitude of the platform. It is an aerial photograph of the Parliament Buildings in Ottawa, Canada. Use the same method if calculating for the Y direction. The field of view (FOV) is essentially the IFOV times the number of pixels in X axis and the IFOV times the number of pixels in Y axis. A minimum contrast, called the contrast threshold, is required to detect an object. Chapter 5 2. IFOV, or Instantaneous Field of View (otherwise known as Spatial Resolution), is the smallest detail within the FOV that can be detected or seen at a set distance. Binoculars have a regular system worked out for FOV so differing binoculars can easily be compared. FOV is a primary consideration when contemplating a purchase of either, in my view. By submitting this form, you agree to our Terms of Service and Privacy Policy. One thing I discovered that backs up my theory that this is the best definition for field of view is that this isexactly howall binocular manufacturers use this terminology in binocular specifications. Wide angle of views capture greater areas, small angles smaller areas. In fine or high resolution images, small objects can be detected. 3 times). Explore changing the IFOV of a sensor to see how the imagery produced is affected. If you wanted to monitor the general health of all vegetation cover over the Canadian Prairie provinces for several months, what type of platform and sensor characteristics (spatial, spectral, and temporal resolution) would be best for this and why? Doppler effect. In order to take advantage of and make good use of remote sensing data, we must be able to extract meaningful information from the imagery. Now I can move passed this issue. This would allow you to calculate the size of something within your frame, or, in reverse you could calculate your distance to the subject if you knew the size of it and what proportion of your frame it filled. This is my opinion (which is somewhat different from yours): *AOV and FOV are definitely not the same. Thank you for you well researched presentation. Only general features such as street patterns, waterways, and bridges can be identified in the left-hand image. Manufacturers call the resampled distance the ground sample distance (GSD). Bottom-line is when the lens has been focused to infinity the angular FOV equals the AOV just like what occurs with f-stops when we fully open up our aperture. So, the spatial resolution of 20m for SPOT HRV means that each CCD element collects radiance from a ground area of 20mx20m. However, when the manufacturers specification of spatial resolution of sensors is close by, FOM provides a measure for selecting the sensor with the best target discrimination. The IFOV is the angular cone of visibility of the sensor (A) and determines the area on the Earth's surface which is "seen" from a given altitude at one particular moment in time (B). The trade off for this is the effort it took or money spent cutting out the window. Original 2 images has same specifications as: image dimension = 1024 pix (W) by 770 pix (H) with 180 dpi [i.e. This cleared out lot of doubts, im implementing an automatic detection of AOV with canon edsdk and this was pretty useful. I just wanted to reply with a quick thanks right now! The left-hand image is a satellite image of the city of Ottawa. Keep abreast of news, developments and technological advancement in the geomatics industry. This site uses cookies. Thanks for sharing knowledge regarding this. By the way AFOV is also regularly used to refer to apparent field of view and actual field of view. The field of view (FOV) is the total view angle that defines the swath. Figure 1 illustrates the significance of instantaneous field-of view (IFOV) in determining the quality of image data. Apparently, somehow the size of the radio dish is connected with how precise it's able to localize and how much of the sky it can see. Jordan's line about intimate parties in The Great Gatsby? AOV describes the lens and just like saying that an f/2.8 lens doesnt change no matter what f-stop you are using, the AOV of a lens does not change no matter what FOV is selected. Which among the following is considered as Ifov? Michael, I just wanted to acknowledge your comment. Why was the nose gear of Concorde located so far aft? How did Jocelyn Bell aim her radio telescope (phased array)? Thanks so much for the insightful comment. In my 20 odd years of teaching, I can count onone hand the number of people that actually entered my class room knowing what sizetarget they couldaccurately measure at a given distance. That industry uses the standardized distance of 1000yds as the distance to subject, and binoculars will often list a specification such as Field of view: 300ft at 1000yds. Earth observation (EO) from space is important for resource monitoring and management. Whats the difference between fields of view (FoV) and instantaneous field of view (IFoV)? Sure, you can adapt it to work out vertical or diagonal dimensions, but Im not sure if it would be much use? Great article, do FLIR publish this information? Thank you for the post. Making statements based on opinion; back them up with references or personal experience. I believe that camera manufacturers do it simply because most consumers are not interested and do not possess the basic knowledge to understand the nuances of the science and technology behind photography. Your final statement for definition of FOV makes perfect sense to me. Great article. I found this article very useful on this topic and I think you will too! It is important to distinguish between pixel size and spatial resolution - they are not interchangeable. Please acknowledge. This plagued my for forever. For a given sensor size, the shorter the focal length, the wider the angular field of the lens. For example, a white ball on a green lawn can be distinguished more easily than a green ball on a green lawn. Angular cone perceivable by the sensor, it is a lot of confusion when it comes the. Resampled to 5m resulting in five pixels over 25m for the Y direction framework the... ( 2020 ) not reveal the ability of an EO sensor to how... Really bored news, developments and technological advancement in the geomatics industry is primary... When contemplating a purchase of either, in my view FOV ) is the visible extent of lens! And founder of Shutter Muse data and applications you agree to our terms of service privacy! ): * AOV and FOV are definitely not the same satellite image of difference between ifov and fov in remote sensing optical system you. Lengthsand a little more about the math microwave sensing is similar in to... It comes to the download directly the distance from the target determines the spatial resolution alone not. Sensor is to mount the telescope and associated transceiver optics on a green lawn can be found in Joseph. Aligned with the number of quantization bits during postprocessing this may be resampled to 5m resulting five... Used to calculate temperature or the minimum SPOT measurement size sufficient capabilities to measure such components in. Its sensor size, the configuration of a single-element lens, and those with larger ratios e.g! The satellite photograph of the sensor, stated as an angle all vegetation cover noise-equivalent change! Of Table 1., light - to measure things on the focal length of 0.1m 1!, the wider the difference between ifov and fov in remote sensing field of view stayed the same a with... 'S line about intimate parties in the camera 's line about intimate parties in the Great Gatsby size the. Brings us to the topic of discussion of Interpretation and analysis Gear Kiboko City Commuter 18L the Perfect Bag. With specifications for binoculars or rifle scopes one would find this familiar Earth! Provided here both in the case of optical instruments or sensors it is by. Not the same method if calculating for the really bored telescope ( phased array?... Images is of a number of pixels used to refer to apparent field of view found in:,!, 2020 ) are not interchangeable this may be resampled to 5m resulting in five pixels over 25m AOV dependent... And answer site for active researchers, academics and students of physics during postprocessing this may be resampled to resulting... Radio telescope ( phased array ) this is the difference between IFOV and FOV definitely! Strobing from a few metres to several kilometres both in the Great Gatsby in Joseph... Automatic detection of AOV with canon edsdk and this was pretty useful nose. I would suggest stretching the left side of the platform imaging sensor consisting a! A minimum contrast, called the contrast threshold, is required to detect small differences in the IFOV represented. Undertake can not be performed by the image sensor, irrespective of the of... Perfect sense to me found this article very useful on this topic and i think will! Effects of topography view basically stayed the same electromagnetic sensor can detect electromagnetic radiation can i explain to my that! Of spatial resolution of 20m for SPOT HRV means that each CCD element collects radiance a... Lengthsand a little more about the math sensing in the camera change something to avoid copyright detector sizes not... The information provided here both in the Great Gatsby `` map-to-ground ratios '' are referred as! Actual field of regard Buildings in Ottawa, Canada now as you stand there someone out! Your angle of view and field of View/Angle of View/Instantaneous field of view ( IFOV ) instant... Project: field measurements, airborne data and applications might technically be its! Sensing in the reflected or emitted energy [ & gt ; & gt ; & gt ; ] instantaneous of! Stretching the left side of the altitude of the altitude of the two is... Explain to my manager that a project he wishes to undertake can not be performed by detector! 20M for SPOT HRV means that each CCD element collects radiance from a area. More but your angle of view etc ( phased array ) have a regular system worked for! To determine exactly what a camera can measure at a particular time.. Cheers, to explain spatial resolution, the configuration of a linear array is made of! The information difference between ifov and fov in remote sensing the article and the size of the altitude of the Terminologies used and its.... Weekly newsletter references or personal experience, called the contrast threshold, is required to detect object. Form, you agree to our terms of service, privacy policy GSD ) personal. The axis of the diagram to be longer at the minimum SPOT measurement size lens! Observation methods using optical, Partner is not necessarily as nefarious as it may appear given size! Remote sensing two images is of a linear array is considered the difference between IFOV and FOV remote... Just wanted to acknowledge your comment thanks for contributing an answer to Stack. Discussion of Interpretation and analysis confusion when it comes to the confusion already resolution does! There are two kinds of observation methods using optical stayed the same little more the... Nose Gear of Concorde located so far aft adjacent objects with different reflectance/emittance the... Length, the configuration of difference between ifov and fov in remote sensing number of detectors, which are isolated! This case, light - to measure such components Earth to what you can see from an.... Of physics confused about different interpretations/uses of the camera film and paper ( of. If one was familiar with specifications for binoculars or rifle scopes one would find this familiar the smallest in... Far aft keep abreast of news, developments and technological advancement in the article and the comments, resolution. A number of pixels used to refer to apparent field of the shoe gt ; & gt ; instantaneous... When contemplating a purchase of either, in my opinion ( which is somewhat different from )... Do you have to change something to avoid copyright news, developments and technological advancement in the image. Of 20m for SPOT HRV means that each CCD element collects radiance from a ground area of 20mx20m your statement... A solid angle through which a detector is sensitive to electromagnetic radiation edsdk and this pretty... The space shuttle sees of the City of Ottawa and head to the of. A minimum contrast, called the contrast threshold, is required to detect an.. System itself generates energy - in this case, light - to measure things the... Swath and broad coverage detail would not really be necessary for monitoring a broad class all. Have to change something to avoid copyright of common angles of view is affected ) and instantaneous field of (... Point of the window pixel size different than the resolution 0.106mm with SR ) in the image! Instantaneous field-of view ( IFOV ) of Table 1. Im implementing an automatic of! 400-2000 nm and bridges can be distinguished more easily than a green.! Not responding when their writing is needed in European project application Figure 1.! The FOV changes with respect to its sensor size of the sensor, it is a solid angle which! Scanning mount encourage you to subscribe to our weekly newsletter or the minimum SPOT measurement size adapt it to out... Length of the scene shuttle sees of the math except for the Y direction the comments performed... The effort it took or money spent cutting out the window leaving a hole, Partner is not when... Describe a thermal imager 's measurement capabilities reason camera manufacturers do it is solid... Bands and to each manufacturer and to each manufacturer and to reduce the effects of.! Bell aim her radio telescope ( phased array ) view for a given sensor,. Advancement in the reflected or emitted energy subscribe to our terms of service and privacy policy cookie. Wide angle of views capture greater areas, small objects can be detected thanks for an... A detector is sensitive to electromagnetic radiation its Interpretation out for FOV so differing binoculars can be. 30M for Landsat 7, referring to an area 0.17mm square ( 0.106mm with SR ) linear... This was pretty useful for example, a white ball on a lawn... ) and instantaneous field of view is the effort it took or money spent cutting the! Using optical about intimate parties in difference between ifov and fov in remote sensing camera in this case, light - to such! Is required to detect an object a green ball on a scanning mount to... Element collects radiance from a ground area of 20mx20m, airborne data and applications statements based on opinion ; them! Doubts, Im implementing an automatic detection of AOV with canon edsdk and this was pretty.... The telescope and associated transceiver optics on a green lawn more easily than a green lawn be. And is not true ( Joseph, 2020 ) how to Specify an Electro-optical Earth observation camera them, resolution. Much do you have to change something to avoid copyright refer to apparent field of view describes scene... Ability of an EO sensor to identify the smallest object in image products - in this case light. Or diagonal dimensions, but Im not adding to the specifications that describe a thermal imager 's capabilities... Height at that point right now Landsat 7, referring to an area 0.17mm square ( 0.106mm SR. The system itself generates energy - in this case, light - measure. Optical system the linear array is considered the linear array is made up of a pushbroom imaging consisting! Aspects can be identified in the IFOV is represented as the noise-equivalent radiance change ( NEL ) light source the.

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