On kps kilo pixel swath - asprs - armando guevara


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On kps kilo pixel swath - asprs - armando guevara

  1. 1. ASPRS Guevara – Visual Intelligence proposed kps definition 1On kps – kilo pixel swathBy Dr. Armando Guevara – www.visualintell.com Rev. 7.24.121. - Concept definition and proposalIn an effort to clearly guide customers’ decision when considering buying asensor the time has come to establish a digital measure that reflects simplysensor collection capacity per unit of time.The term “frame” (as used in the aerial film paradigm) no longer makes sense inthe digital world and is increasingly confusing to the end customer. Whenevaluating a new camera, vendors will show up with very large frame, largeframe, medium frame systems, and they are all different sizes. The term“megapixel” can also be confusing since it is not a clear metric of mappingcollection capacity.With sensor evaluated attributes all being equal “apples to apples”- i.e. all havethe same image geometric and radiometric quality, performance, reliability, easeand speed of workflow etc., a pivotal selection criteria is the cost of ownershipand operating cost; both of which are impacted by collection cost. A keyefficiency of collection metric/attribute is defined by: “At a required GSD, howmuch area can be collected in a given unit of time”. The answer to this iseffectively defined by the swath of the sensor in number of pixels.2. - Introducing “kps”A kps is the number of pixels across track covered by a sensor, in other words,the number of pixels in the swath. 1 kps = one thousand pixel wide swath.Example: collect at 1 foot pixels (30 cm) –impact of kps
  2. 2. ASPRS Guevara – Visual Intelligence proposed kps definition 23. - kps - a base measure to establishing digital aerial camera collection efficiencyIt is often difficult to differentiate the competing claims of different digital aerial cameramanufacturers when it comes to efficiency. There are many aspects that contribute tothe efficiency, but one simple measure is for the same aircraft speed, how much area iscollected per hour of flying?There are many factors that impact the cost of a successful aerial metric geoimagingproject, including but not limited to camera focal length, CCD size and flying height. Fordigital cameras, the project is designed for a specific nominal ground sample distance orGSD. No matter what flying height, focal length, or CCD size, the amount of areacovered is the nominal GSD times the number of pixels in the selected width of the CCDarray (x or y orientation – typically the largest number of pixels on the CCD is in x so ifmore depth is desired the CCD can be rotated with x becoming y).Normal block collection of a project will factor in a 30% side lap between flight lines.Examples of pixels swath with “CCD configurations” of:A. 7 kps will have an effective swath 5051 wideB. 11 kps will collect a swath 8,043 wideC. 19 kps will collect a swath 13,280 wideD. …and so on.kps Width30%side lap7 5,051 2,16511 8,043 3,44719 13,280 5,691In a project example with a flying speed of 150 miles an hour times 5,280 feet in a mile,the aircraft travels approximately 792,000 feet an hour. Efficiency results for the abovekps example are shown on the following chart:TraveledDistance/hour Width sq feet sq miles EfficiencyA 792,000 5,051 4,000,550,400 144 1.00B 792,000 8,043 6,370,056,000 228 1.59C 792,000 13,280 10,517,522,400 377 2.63