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Geoinformatics_06-2009
article fig. 3 the rcd105 camera system that can be supplied for use with the leica als series of airborne laser scanners with the ch39 camera head sitting on top of the case containing the cc105 camera controller. of focal plane shutter offers the unique feature of being removable and can be replaced in the field without the need to remove the lens or to re-calibrate the camera unit. the use of this type of shutter - which takes a very short but finite time to cross the focal plane - also means that the exposed image is very slightly elongated in the flight direction. however this effect is removed during the post-processing of the exposed image. als corridor mapper models. the rcd105 can be operated up to the maximum ceiling of the als scanners. in the case of the als50-ii, the maximum flying height at which the instrument can be operated is 6 km above ground level, while the newest als60 model that was introduced at the isprs 2008 congress can be operated at altitudes up to 5 km over the terrain. both of these scanners can be used for the generation of elevation models over large areas of terrain. by contrast, the als corridor mapper is a lower-cost model that is designed specifically for corridor mapping at large scales (along roads, railways, rivers, pipelines) from much lower flying heights with a maximum operational altitude of 1 km above ground level [fig. 4]. with these very different laser scanner applications and operating altitudes in mind, it is interesting to note the wide range of angular and ground coverages that are provided by the alternative lenses that are available for the rcd105 camera system - as set out in table i. fig. 5 the leica geosystems rcd100 mediumformat digital frame camera system in its housing. rcd100 camera by contrast, the leica rcd100 is a fully integrated stand-alone system combining (i) either a single or dual ch39 camera unit; (ii) a cc10 camera controller; (iii) an ipas20 positioning and orientation system; and (iv) a rcd105 camera the rcd105 system comprises the ch39 camera together with its cc105 controller which is interfaced directly to the camera [fig. 3]. the controller can in fact control the operations of two ch39 cameras mounted side-byside to acquire colour (rgb) and false-colour (cir) frame images simultaneously and to record and store the resulting data on two removable solid-state (flash) memory units that can be exchanged in-flight. the rcd105 was the first model in the series that was introduced to the market in 2007. it was developed specifically for the acquisition of digital frame imagery concurrent with the laser scan data being acquired by the latest models in leica s als series of airborne laser scanners - including the als50-ii, als60 and the pav80 gyro-stabilized mount [fig. 5]. the first three of these units are tightly coupled together inside a specially-built chassis and temperature-controlled housing. this then fits into the pav80 mount. the ch39 camera units have already been discussed above. the table i - ch39 lenses and their respective gsd values, angular and ground coverages and base:height ratios fig. 4 the leica geosystems als corridor mapper. the laser scanner is contained in the box located at left rear, while the large electronics cabinet at the right rear contains the controllers for both the camera and the laser scanner. at the front, the rcd105 camera has been placed between the two display monitors for the pilot (at left) and the systems operator (at right) respectively. ipas20 (inertial position & attitude system) combines an imu (inertial measurement unit) and a geodetic quality gnss receiver. the imu is located directly above the ch39 camera unit in a very rigid mount. above this sits the cc10 camera controller, including the removable solid state drives. finally the ipas20 electronics cabinet which contains the controller boards, real-time firmware, gnss receiver and the storage card that is used to record the measured imu and gnss data is mounted at the top of the stack of units accommodated within the rcd100 housing. a range of imus with different capabilities is september 2009 latest news? visit www.geoinformatics.com 55
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