How To Calculate Distance From Camera To Object

Linear perspective was a big step, but with careful observation it became apparent that other natural phenomenon were at work altering the look of distant objects. Left/right is 0 to 319 and up/down is 0 to 199. The range tells what the minimum and maximum temperatures are that the camera can measure (-4°F to 2200°F is. More specifically, the camera is always located at the eye space coordinate (0. but I found the distance changed when my iphone camera far or near from the. For making more cinematic screenshots, use a smaller FOV and a larger camera-object distance. With its amazing 3D camera overlay grid, using EasyMeasure is very intuitive and easy! Find out how far it is towards that boat at the other side of the lake. How is 3D motion data obtained in an optical motion capture system? In an optical motion capture system, multiple synchronized cameras are installed around the target capture volume, and 2D images are captured from each camera. The app uses the height of the camera lens and its tilt angle to figure out the distance to the object. Return distance between iterators Calculates the number of elements between first and last. It's a passive focus. also is it possible to get distance between the camera and multiple objects?. Distance Calculation Model. This example shows how to create a 3-D object that looks like a flat sheet of paper which has been rotated. Prepare your art. This handy field of view calculator will help you in determining which lens is right for your application. In a physics equation, given a constant acceleration and the change in velocity of an object, you can figure out both the time involved and the distance traveled. eg Tracking a moving object like a train and calculating it’s speed etc. They are commonly found in printing, converting, robotics, material handling and transportation industries. This distance from front to back that will be in reasonably sharp focus is called the depth of field. Example: if distance_to_object(obj_Player) < range { canshoot = true; }. It does this in one of two ways. To make it easy to calculate the horizontal and vertical image size that you will get of an object at various distances from the camera. If you shoot a crop sensor camera (Nikon D3300, D5500, D7200, or Canon Rebel, 70D, 7D, Fuji XT1, or Sony A6000 just to name a few), then your camera's crop factor will make your camera more zoomed in when compared to full frame cameras at the same focal length. The distance to the object is not the distance to the object. In this example we will place the camera closer to the height of the person, because the goal is identification. That includes a lot of stars, but is only a small fraction of the size of our galaxy. The idea is to scale actor based on the distance from the camera (which is already easy to get). This tutorial will explain how to build an inexpensive IR distance sensor under $8, perfect for close measurements and motion detectors. now i want to know the distance to it without driving there to get its gps-coordinates. See distance to other cities from Gold Coast – Queensland – Australia measured in kilometers (km), miles and nautical miles and their local time. I'm looking for a formula to calculate the horizontal distance (guess it is the Ground Distance) passed during the phase of ascent (or descent), having the rate of climb in ft/min and the TAS in knots. Quick examples I hold out my arm, look at my thumb, and see a distant car half as. Return distance between iterators Calculates the number of elements between first and last. Using the minimum focus figure, measure between the camera’s sensor plane and the object you want to photograph. You will define fields, methods, and properties for the class. However, the camera wasn't on the ground but rather in my hand. • CCD - The size of the camera’s image sensor device. Many camera apps offer an option to shoot in RAW format in addition to the standard JPEG. Calculating the distance between an object and a camera in not an easy task. In photography, the focal length of a lens is the distance between a the camera's sensor and the internal components of the lens itself. You should be able to understand all the code by now. hi all, i'm having a slight problem that i cannot find a solution on google. Technical Writeup Posted on 01 October 2016 by Flafla2 Raymarching is a fairly new technique used to render realtime scenes. from the lens, the film must be placed a distance y behind the lens. A calculator at the focal length of a magnifier. One of the most striking differences between your iPhone and a large camera like a DSLR is the way the two cameras focus and control depth of field. If a subject is close to the camera, even slight movement is enough to cause blur. Different lenses have different focal lengths, and along with the object's distance from the lens surface, this can be used to determine magnification in physics. Here are some simple tips to help you take even better ones — and enjoy them — with your iPhone. This article is a comprehensive overview of using deep learning based object detection methods for aerial imagery via drones. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. If you have stereoscopic images you could calculate the distance between the matched blobs and use that as additional data for calculating distance (the further apart they are the closer the object is to the camera). My findings tell me that the Kinect's depth measurement as a function of distance is not linear… It appears to follow a logarithmic scaling. Estimating Distances to Far-away Galaxies There are many different methods -- none of them very good -- which we can use to estimate the distance to far-away galaxies; or, more accurately, estimate the relative distances of a far-away galaxy and the LMC. 6 has a new Audio element which can be very useful in animations as it plays audio files and the distance between camera and audiofile can determine the audio level automatically. Objects far away from the camera then produce sharp images on the sensor or film, which is also at the image plane. I have detected the object by using OpenCV and /brg/image_raw topic from Astra camera. As detailed in our previous blog post, our reference object should have two important properties:. In the figure above, click 'reset' and the "Show Triangle" checkbox. And thank you for taking the time to help us improve the quality of Unity Documentation. Some also said that it fails to auto focus or takes a long time to do so. Your back-up camera is located in the rear of your car. The best way to calculate hyperfocal distance is to use the “double the distance method“, where you approximate the distance from your camera to the nearest subject you want to be sharp, then simply double that distance. The 3D camera motion allows you to correctly composite 3D elements over your 2D footage. The maximum distance allowed between the lens and the film plane is 140mm. The object of the converging lens is the image of the diverging lens. CaMeasure lets you use your camera to measure size or distance. This is called "maximum surface stress" and is typically represented by the sigma sign. Since the duration of the pulse is the time it took for the ultrasonic sound to hit an object and bounce back, we will just use half the speed to calculate the distance it traveled before returning. If your camera doesn’t provide a mechanism for controlling aperture, then you won’t be able to choose a particular depth of field. It's kind of an assumed topic that doesn't get enough attention. Lens Magnification Calculator. Using this. To calculate hyperfocal distance, square the focal length, and divide that number by the aperture number times 0. I find some programs that allow me to recongnize the object that I look for and I have an algorithm which calculate the position of the pixel center in the object in matlab. In general, it is not possible. (a) How far ahead of the sensor should the lens be if the object to be photographed is 10:0m away? Solution: We find the image distance from Eq. Here is an example on how to calculate speed of a car:. He had spent some time researching, but hadn’t found an implementation. Based on the displacement of the pattern due to objects in the scene, it can calculate the distance of the objects from the camera. In a follow-up segment, I will discuss the different autofocus modes and how to best use them to get the photographic results you seek. The parallax formula states that the distance to a star is equal to 1 divided by the parallax angle, p, where p is measured in arc-seconds, and d is parsecs. It turned out to be that the photo was taken at a distance of around 150 meters. With this calculation, you can then apply the results to the Johnson Criteria DRI levels to determine the answer to, How Far Can I See? How to Calculate How Far Can I See? For the purpose of explanation, the following criteria are used to demonstrate how to perform the calculations: GIVEN. Within sometime you distance will be known and once the distance is known using the trigonometry we can calculate the height of the object. The Field of View Calculator (or FOV) is used to help predetermine proper lens selection prior to installation. The human eye also has a lot more pixels than your camera, about 130 million pixels (you 24-megapixel camera owners feeling humble now?). Raymarching Distance Fields: Concepts and Implementation in Unity. I have disparity map using stereo camera pair. Draw a dot perpendicular to that line, at a distance equal to the focal length. How can we extend these results for nearby stars to objects halfway across our Milky Way Galaxy, or to. 87 (c) How far must the lens be moved with respect to the film when an object moves from infinity to a point 2. As we approach the object we will see it larger (fig. Keyboard controls By using your keyboard and mouse to control the camera, you can view nearly any object or avatar from any angle or distance. If a subject is close to the camera, even slight movement is enough to cause blur. Get corrections from Grammarly while you write on Gmail, Twitter, LinkedIn, and all your other favorite sites. The distance to the object is not the distance to the object. The normal focus mode of most digital cameras is some sort of average focus mode. Estimating Distances to Far-away Galaxies There are many different methods -- none of them very good -- which we can use to estimate the distance to far-away galaxies; or, more accurately, estimate the relative distances of a far-away galaxy and the LMC. Some also said that it fails to auto focus or takes a long time to do so. Object definition is - something material that may be perceived by the senses. The angular size, linear size and distance can be calculated using the formulas: Thus, we can find out distance from the object if we knew its size and its angular size. Important: Every lens has a minimum object distance (MOD). Both of these figures should be expressed in bytes per second. These sensors detect objects behind your car. To use the lens equation for the thick lens, we must find the object distance to the first principal plane H 1, so we must calculate. And thank you for taking the time to help us improve the quality of Unity Documentation. ) The camera is looking at the base of the pyramid. Below is the online magnification equation calculator based on the image distance (d i) and object distance (d o). You have to know the approximate (x,y) dimensions of the object that you want to detect. If i want to measure a distance behind or in front of the marker: wrong. It also is called the object's angular size. If the point you want to measure is too far away, you'll be prompted to choose a closer object. Describe the appearance of the image, compared to the object (e. distance gives me a overload error. As detailed in our previous blog post, our reference object should have two important properties:. using triangulation method i can find the height, if the distance between the camera and the object. I hope the above steps were helpful. In order to calculate the size and the position of that image, two equations are required. I averaged those values to come up with my measurement for each distance. PHOTO SCALE = Photo Distance / Ground Distance Note: Unit of both distances should be in the same unit. With its amazing 3D camera overlay grid, using EasyMeasure is very intuitive and easy! Find out how far it is towards that boat at the other side of the lake. I am tracking that object. It does this in one of two ways. Focal distance – Determines the distance from the camera at which objects will be in perfect focus. Where is the image? Now move the Object in to 2*f distance to the left. If the closest object in your photo is a patch of grass one meter away from you at the bottom of your composition, find something that’s about 2 meters away, and focus there. A simpler mathematical explanation may help more. I need to what is the minimum distance of any pixel infront of the camera. For example, if it is a frontal face, you have an idea of the approximate dimensions it has. to an object using the camera? i want to point to an object with the camera and then show the distance to it in the display. The technique is particularly interesting because it is entirely computed in a screen-space shader. The app then uses that to calculate size. 2D positions are calculated, and the overlapping position data are compared to compute the 3D positions via triangulation. This article. Your acceleration is 26. A lens produces images in the form of a circle, called the image circle. This distance. Doing this is a simpler calculation then calculating the distance with the full speed then dividing by 2. I am tracking that object. In the middle of the 2nd century BCE, Greek astronomer Hipparchus pioneered the use of a method known as parallax. A coincidence rangefinder or parallax rangefinder can be used to find distance to a target. To accomplish this task we utilized the triangle similarity, which requires us to know two important parameters prior to applying our algorithm: The width (or. (Only the lower triangle of the matrix is used, the rest is ignored). Horizontal Focal Length. Follow the below given steps to recover deleted objects in Windows Server 2012 and Windows Server 2012 R2: Navigate to start and type dsac. If i dont have the marker the results are wrong. 5 cm from a convex lens having a focal length of 16. The process of getting the object’s distance from the camera is pretty straightforward: we get the world position of the object and the world position of the camera and we get their distance using the built-in “distance” function. The maximum distance allowed between the lens and the film plane is 140mm. Now suppose a camera has a lens with focal length F = 65. You can use triangle similarity to calibrate the camera angle and find the distance. The distance of the object varies inversely with disparity and the accuracy of distance measurements depends on resolution of the camera pictures, lens optical properties and separation between the optical axes of both cameras. How does the height of a camera lens and a tilt angle allow to calculate a 3D distance? I thought that a point on a 2D space (what a camera sees) represents a line in 3D so it's impossible to calculate real distance with 1 camera and no objects of reference. Find Path to Location Synchronously not working on client. Now calculate a vector from each camera to your object. Note that the script doesn't simply point the object at the camera. Depth of field defines the distance between the nearest and the farthest object from the scene that appears "reasonably" sharp in the image. The speed of an object is a measure of how far it moves in a set time period (measured in the units meters or feet per second, km or miles per hour etc. Divide that by two to get the distance to the object. 5, supports object avoidance using a Lightware SF40C, TeraRanger Tower or with any sensor capable of providing distances using the MAVLink DISTANCE_SENSOR message. General FAQs 1. "Right above the focusing ring and next to the Nikon name is the distance indicator window, which tells you in feet and meters where the lens is focused at any given point. The process of getting the object’s distance from the camera is pretty straightforward: we get the world position of the object and the world position of the camera and we get their distance using the built-in “distance” function. That point will remain anchored to the object in the real world, even as you move your phone around. For making more cinematic screenshots, use a smaller FOV and a larger camera-object distance. 1 m from the camera? in cm. If the object fell 4 ft during the 1st half second, how far did it fall during the next 2 seconds? I know the answer is 96ft but im not sure how to set it up. Complete Digital Photography, Ben Long, 2012. ” If it flops down when held, you either have an undercooked crust or one that is too wet. How do I calculate the object-space distance from the viewer to a given point? Transform the point into eye-coordinate space by multiplying it by the ModelView matrix. CaMeasure lets you use your camera to measure size or distance. hello everyone, want to measure distance between two objects in a image. I would like to know what are the coordinates of each vertex in the rendered image (i. It's the part that is "in focus. Objective: Distance measurement between a robot and the object is needed to control the action of the robot such as grabbing an object or even avoiding obstacles. This is based on both the camera type (sensor or film size), and on the viewing distance / print size combination. Lastly, we set isGrabbed to true so that our game knows that we are in possession of an object. #F_g=(GMm)/R^2#. Compressing Distance. You can still focus an object at infinity OK, but what distance do you measure?. This PowerPoint trick can help you to align shapes and objects across multiple slides in PowerPoint presentations. Note, however, that the objects in both images remain at the same. The eye is an example of a naturally occurring entity that includes a lens. if you’re shooting an object that you’re going to put. model that predicts distance perception on the basis of either binocular cues or accommodation would predict that the object would be seen as extremely close (and implausibly small). In a follow-up segment, I will discuss the different autofocus modes and how to best use them to get the photographic results you seek. First, the one camera's image is stored in an array. But even though the NHTSA rule doesn't go into effect for several years and many more cars now have cameras, you don't have to wait until your next vehicle purchase to get a back-up camera for an. Example: if distance_to_object(obj_Player) < range { canshoot = true; }. Use a flat surface, a chair, or a tripod to steady your hand or camera while taking the photo. by Elizabeth innocuous objects with a small hole for the camera. focus distance – If specify focus is enabled, specifies the distance at which objects are in focus. This speed calculator is a tool that helps you determine the average speed of a moving object based on the distance traveled over a certain time traveled. The speed of an object can be found by taking the distance it travels and dividing it by the time it takes to ravel that distance. The object can be an object index or a specific instance id as well as the keyword other, and the distance is returned in pixels. CaMeasure lets you use your camera to measure size or distance. Below is the online magnification equation calculator based on the image distance (d i) and object distance (d o). In the latter case you enter the size and distance of a hypothetical reference object and its desired projection size in the camera image. The width of the received pulse is then used to calculate the distance to the reflected object. You can find the location of this plane by projecting the image ray backwards through the system to where it crosses the projection of the object ray. How do I determine camera's 3D position and orientation? viz lobject/Limag. Working distance (WD): Distance from the front of the lens to the object under inspection; See the following images for reference: Follow two main steps to pick the minimum required camera resolution and to determine the correct focal length for your application. Abstract The goal of our project is to develop a general machine learning framework for classifying objects based on RGBD point cloud data from a Kinect. The Picture will be saved automatically. If you find yourself facing this predicament, flag down a server to see if you can have the kitchen flash it in the oven for a more solid slice. Objects closer than this will appear in front of the screen, objects further than the focal length will appear behind the screen. For another method of measuring distance traveled and velocity of an object rolling down an inclined plane, see the Science Buddies project, Distance and Speed of Rolling Objects Measured from Video Recordings. I need to what is the minimum distance of any pixel infront of the camera. This article contains an introduction to how to focus a landscape scene in order to make a sharp high resolution image. How can I measure 3D coordinates of a target, using a camera? Hello, How can I measure 3D coordinates of a target, using a camera? (distance from the object, general orientation +/-15deg, etc. Positions an object to the closest intersection of the grid even when the grid is not visible. Raymarching Distance Fields: Concepts and Implementation in Unity. see this : Finding distance from camera to object of known size. Fortunately, this problem can be easily solved with extension rings that are put between the lens and the industrial camera. Position the painting on a wall. Determine the object distance and image distance, o and i, and calculate the focal length from the lens relationship. • Surface properties are stable (same object) within a given time period • only change must be due to % filled FOV (represents x-y motion) • We can therefore calculate the % of the Field of View filled by the object • Independent of object distance! 27 20% 80% 100% 80% 20% Amplitude can be normalized (using distance info). It is important to know that to get everything in focus, you do not have to focus on the object that is farthest away from your camera. The terrain at distance 100 for example has a depth of 4. As a metaphor. How to Use Laptop Camera for Recording Video. If you can find some objects in your photos whose sizes you know, you can measure their distances and if you know the distance of an object, you can find the size of it. The distance between your infrared thermometer and the target; Distance to Target Ratio. Download free trial Order now. The actual distance and the two conflicting predictions for the perceived distance of the object are summarized in Table 1. (Only the lower triangle of the matrix is used, the rest is ignored). Right now im writing my final year project about exacly that topic, took me 2 months and a special designed marker to achieve the measurement of distance and angle from the camera to the object. The formula s=16t^2 is used to approximate the distance s, in feet, that an object falls freely from the rest in t seconds. The movie shot lists and storyboard examples highlight how filmmakers combine various types of shot and shot angles to amplify the scene's cinematic effects. That means the sound has to travel this unknown distance twice (there and back). Is it possible to calculate the distance from the camera by looking at the focus position. a) How far ahead of the film should the lens be if the object to be photographed is 10. I'm in the last year of my school study. With an orthographic projection, the viewing volume is a rectangular parallelepiped, or more informally, a box (see Figure 3-15). If the distance to the ball is changing, the 10px = 1cm would change too, and everything would be wrong. To render closer objects in sharp focus, the lens must be adjusted to increase the distance between the rear nodal point and the film, to put the film at the image plane. Prepare your art. Wait for a Few Seconds as the response time is slow. Accessing the Distance Matrix service is asynchronous, since the Google Maps API needs to make a call to an external server. Copter Object Avoidance¶ ArduCopter, from release 3. When it comes to. By following these quick steps you can learn how to use the 'Link Focus Distance to Layer' feature in After Effects: 1. Click on calculate >> distance Fill in 95 km/hr and 16 hours. A film camera uses a single lens with a focal length f = 58 cm. Having a correct PD on your glasses prescription insures that you are looking through the ideal spot in your lenses. Unfortunately you can't estimate the real size of an object from an image, since you do not know the distance of the object to the camera. Your acceleration is 26. Estimating Distances across our Galaxy Hipparcos measurements provide accurate measurements of distance for stars which are within about 100 to 200 parsecs. Technical Writeup Posted on 01 October 2016 by Flafla2 Raymarching is a fairly new technique used to render realtime scenes. When you switch over to the next level up, the premium compact camera, you often find a larger sensor for improved image quality. mm (b) Calculate the image distance for an object that is 2. Camera calibration + distance to object This is not a Matlab specific question, but I'm using Matlab tool so hoping somebody else can shed some light. It will measure the distance between the point you placed and whatever is under the dot at the center of your screen. Position your camera so that the space that you want to monitor is within the camera's field of view. So just find a motivation here before we start writing our own types of objects is the advantages of object oriented programming is really that you're able to bundle this data, bundle some internal representation, and some ways to interact with a program into these packages. These two functions are. When the lens is. Most probably all you need to do is to just replace the camera. 1 may become trivial. To calculate the average speed of an object, we do not care about. PHOTO SCALE = Photo Distance / Ground Distance Note: Unit of both distances should be in the same unit. He had spent some time researching, but hadn’t found an implementation. Most smartphones come with a serviceable app, but there are third-party apps that offer many of the same manual controls as a DSLR camera that you can use to customize to your needs. When positioning your Arlo camera, keep these tips in mind: Keep active locations in the camera's field of view. verify objects using camera location and other scene parameters. Includes focal length, for. I don't know if I understood you correctly, but for this to work, you need to already have all the necessary information, that is the distance and the position of the object. To calculate hyperfocal distance, square the focal length, and divide that number by the aperture number times 0. Angle of Elevation Calculator. As long as you don't move the camera, and you keep the ball in the center of the table, you'll know how to calculate the distance by converting from your scale on the background cloth. Lenses magnify and otherwise alter images of objects. Now calculate a vector from each camera to your object. Hence, the distance between the sensor and the object is one-half the distance traveled by the sound wave. Recall that everything from half your hyperfocal distance until infinity is in focus; so, to find the hyperfocal distance for a given scene, you can simply double the length between your lens and the closest object in your photograph. Quick examples I hold out my arm, look at my thumb, and see a distant car half as. (a) How far ahead of the sensor should the lens be if the object to be photographed is 10:0m away? Solution: We find the image distance from Eq. The x axis shows distance from the sensor, and the y axis shows "blur" measured in mm. Realistically two different cameras are required because one camera only gives two-dimensional information. Note that in the simple case, where the object is seen right in the middle of the camera, the solution would simply be (camera. A film camera uses a single lens with a focal length f = 58 cm. Formal Definition. As you move the lens, you can line up the focused real image of an object so it falls directly on the film surface. inputs such as camera height, camera pitch angle and camera field of view for computing the depth of field and 3D coordinates of any given point in the image. (If this doesn't work, you may have incorrectly placed the view transform on the Projection matrix stack. Objects that aren’t typically picked up, moved around, or examined are common targets. // Vary the parameters below to // get different control effects. 10 camera settings you need to learn to master your Nikon. That axis must be normal to the plane along which you want to have your position. Distance of a Point to a Ray or Segment. If you plug the numbers into your calculator (or do the math in your head) you should end up with a depth of 9 km!. There are two basic steps to calculating bandwidth requirements: Determine the amount of available network bandwidth. Use this online convex mirror equation calculator to find the focal length, image and object distance. Point-to-point cameras: better than average at nabbing slowing only for fixed speed camera sites and for lower speed limits if posted. January 2012; New version 0. To use the lens equation for the thick lens, we must find the object distance to the first principal plane H 1, so we must calculate the distance from the front vertex to that plane. if you’re shooting an object that you’re going to put. Is Intel® RealSense™ Depth Camera D435 Compatible with SLAM? Intel® RealSense™ Depth Camera support for Windows* Hello Which Intel® RealSense™ Camera is Better Suited for Scanning Objects at Longer Distances?. It's the part that is "in focus. When and how to use. distance between image and diverging lens has been calculated to be -32cm, and it is right. The working distance is the distance from the front of the lens to the object under inspection. The object can be an object index or a specific instance id as well as the keyword other, and the distance is returned in pixels. To adjust the objective working distance, translate the slider back and forth to change from regular working distance values through Extra Long and Super Long working distances (ELWD and SLWD, respectively) utilized on reflected light and inverted microscopes. Snap objects to grid when the gridlines are not displayed. This is rather specialized, but people do ask how to determine or measure the distance or size of an object or subject in a photo image. The movie shot lists and storyboard examples highlight how filmmakers combine various types of shot and shot angles to amplify the scene's cinematic effects. When shooting a target on a wall, level your camera and aim for a vertical wall. C# is an object-oriented programming language. Using the Calculator. His three loves are collaboration, learning new things, and his amazing wife. To accomplish this task we utilized the triangle similarity, which requires us to know two important parameters prior to applying our algorithm: The width (or. Testing to determining the distance from the firearm to the questioned garment will come next and can involve two distinctly different tests. In the wide angle cases, the distance between the camera and my daughter is short compared to the distance between my daughter and the. A video shows 100 tons of old munitions being blown up. Is it possible to calculate the distance from the camera by looking at the focus position. The Object Size Calculator is used to calculate the visible image size from a particular distance. Can anyone please share some suggestion?. This is where the best-measuring apps for Android come into play, they may not be as accurate as any measuring tape but, they will give you a general idea of the length or. This project is used to compute the distance from a known object in an image to our camera. Measuring up. A sensitivity of 0. Then count how many of each number. If we’re planning to detect and recognize objects from the feeds of an IP Camera, all we need is to obtain the address of the IP Camera and load it with OpenCV, as seen in the example below:. I have had this idea for some long time now (6yrs+) but havent really had a chance to develop it further. 1 m from the camera? in cm. This calculator computes the Field of View seen by your camera and lens. You may find that with your camera manual focus, is faster and more dependable than auto focus. Field of View is of course an angle which depends on the focal length and sensor size, but it also computes dimensional field of view size at some specific distance, like at the subject distance, or at a background distance. And I realized that there was one extra low. Others are: Distance from a point to a vertical or horizontal line; Distance from a point to a line using line equations; Distance from a point to a line using a formula. Can anyone please share some suggestion?. To do this, place an object in front of your sensor, measure the distance, then look at the printf output reading. For free audio samples also look at: FreeSound. The best way to determine which camera will capture the full area you are interested in monitoring is to look for the camera's field of view.