Investigation of the Kodak DCS460 digital camera for small-area mapping

Mason, Scott; Rüther, Heinz; Smit, Julian

doi:10.1016/s0924-2716(97)00010-5

Cited by 30 publications

(21 citation statements)

References 10 publications

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“…Dean et al 2000). However few digital cameras can match the spatial resolution of 35 mm fi lm in SLR cameras (Mason et al 1997, Gaffrey et al 2001) so some details such as small GCP markers or thinner branches would have been lost. Preliminary tests of our method using a 2.3 Mpixel digital camera indicated that the CCD resolution was suffi cient for trees under about 25 m tall but insuffi cient for locating some GCPs on trees taller than about 40 m (where the camera is 40 m or more from the buttress).…”

Section: Potential Applicationsmentioning

confidence: 99%

Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools

Dean¹

2003

Silva Fenn.

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A method of estimating trunk and branch volumes of single trees is presented that uses a combination of elementary fi eld measurements, terrestrial photography, image rectifi cation and on-screen digitising using commercial software packages and automated volume calculation. The method is applicable to a variety of different sized trees in situations where the trunks are clearly visible. Results for taper measurement and wood volume calculation are presented for Eucalyptus regnans F. von Muell., Sequoiadendron giganteum (Lindley) Buchholz and Quercus robur L. Branch allometrics are provided for E. regnans. The largest errors arose from fi eld observations. If the trees are asymmetrical in cross-section (e.g. due to irregular buttressing or forked stems), or if there is no vantage point perpendicular to the direction of lean, then photographs from more than one side are recommended. Accuracy and precision of geometric reproduction by the image rectifi cation process, and the volume calculation, were tested using mathematically generated tree components. The errors in the branch volumes of the virtual tree showed complex trends due to interacting factors. Volumes were underestimated by an average 0.5% for stems and 4% for branches. Due to the area defi cit resulting from non-circular cross-sections of the buttress, overestimation of stem volumes could be as high as 10% on average for mature trees. However, the area defi cit was known for E. regnans and incorporated into the volume calculation. The underestimation of volumes would help counteract overestimation due to the area defi cit. The application of this method to carbon accounting in forests and woodlands is explained.

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Section: Potential Applicationsmentioning

confidence: 99%

Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools

Dean¹

2003

Silva Fenn.

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“…Since most shacks are only in the vicinity of 2 m to 2·5 m in height, the accuracy of this differencing operation needs to be at the 0·5 m level or better. In the initial trial covering the Marconi Beam informal settlement (Mason et al, 1997b), the accuracy level attained was somewhat poorer than anticipated, with the strip of six images yielding 0·4 m accuracy. This was mainly as a consequence of a geometry which was weaker than its design (high percentage overlaps) and an image co-ordinate measurement accuracy which was closer to half a pixel.…”

Section: High Resolution Digital Still Videomentioning

confidence: 79%

“…In the first application of DCS460 aerial imagery to informal settlement mapping, an imaging scale of close to 1Ϻ18 000 was adopted (Mason et al, 1997b). This provided an image footprint of about 510 ϫ 340 m and a stereomodel area of close to 300 ϫ 340 m. An important consideration in the adoption of the 520 m flying height was that it yielded a 0·18 m ground pixel size, a sample of the imagery being shown in Fig.…”

Section: High Resolution Digital Still Videomentioning

confidence: 99%

Image Sources for Informal Settlement Management

Mason

Fraser

1998

The Photogrammetric Record

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Informal settlements are a common feature of developing countries. In South Africa the improvement of living conditions in these settlements and the upgrading to formal housing types are regarded as being of central importance to the nation's development. Effective settlement improvement and upgrading activities, which we here term "management", require adequate spatial data. To date, the acquisition of spatial models of informal settlements has been based on conventional mapping techniques, and mostly on photogrammetry. Data are compiled using analogue or analytical methods. These are manual and hence require both considerable expertise and expensive equipment. Moreover, these methods are uneconomical over the often relatively small, densely populated areas covered by informal settlements and are also too expensive to employ with a regularity required to support such tasks as change detection. Alternative imaging sources and mapping techniques are therefore needed.In this article we examine the problem of spatial information acquisition for informal settlement management from three perspectives: spatial information requirements, the role which imagery can play in satisfying these spatial information requirements, and effective imaging options. We focus on the potential of high resolution satellite imaging, small format digital aerial imagery and digital multispectral video systems for rapid mapping. We also discuss the example of automated shack extraction from aerial imagery.

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“…An accurate determination of the camera's interior and exterior orientation parameters is needed for calibrating a camera. Many calibrating techniques have been developed in the last few years: Mason et al (1997), Karras and Mavrommati (2001), Honkavaara et al (2006), Remondino and Fraser, (2006), Douskos et al (2007), Grammatikopoulos et al (2007), Wang et al (2008, Zhang et al (2010) and others, but there are not many calibration techniques in which the images are taken from UAVs. Also in Clarke and Fryer (1998) can be found a review of some calibration methods.…”

Section: Introductionmentioning

confidence: 99%

Digital Camera Calibration Using Images Taken From an Unmanned Aerial Vehicle

García

Agüera

Carvajal

2012

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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Commission I, WG I/V KEY WORDS: Unmanned Aerial Vehicle, camera calibration, UAV photogrammetry, Photomodeler Scanner, Microdron ABSTRACT:For calibrating the camera, an accurate determination of the interior orientation parameters is needed. For more accurate results, the calibration images should be taken under conditions that are similar to the field samples. The aim of this work is the establishment of an efficient and accurate digital camera calibration method to be used in particular working conditions, as it can be found with our UAV (Unmanned Aerial Vehicle) photogrammetric projects. The UAV used in this work was md4-200 modelled by Microdrones. The microdrone is also equipped with a standard digital nonmetric camera, the Pentax Optio A40 camera. To find out the interior orientation parameters of the digital camera, two calibration methods were done. A lab calibration based on a flat pattern and a field calibration were fulfilled. To carry out the calibration, Photomodeler Scanner software was used in both cases. The lab calibration process was completely automatic using a calibration grid. The focal length was fixed at widest angle and the network included a total of twelve images with ± 90º roll angles. In order to develop the field calibration, a flight plan was programmed including a total of twelve images. In the same way as in the lab calibration, the focal length was fixed at widest angle. The field test used in the study was a flat surface located on the University of Almería campus and a set of 67 target points were placed. The calibration field area was 25 x 25 m approximately and the altitude flight over ground was 50 m. After the software processing, the camera calibration parameter values were obtained. The paper presents the process, the results and the accuracy of these calibration methods. The field calibration method reduced the final total error obtained in the previous lab calibration. Furthermore the overall RMSs obtained from both methods are similar. Therefore we will apply the field calibration results to all our photogrammetric projects in which the flight high will be close to 50 m. KURZFASSUNG:Kamerakalibrierung bezeichnet ein Verfahren, welche die Parameter einer Kamera bestimmen. Die Bilder müssen unter den gleichen Bedingungen wie auf den Feldproben gemacht werden. Das Ziel des Beitrags ist es, eine benötigte Methodologie für Kamerakalibrierung mit UAV Photogrammetrie zu erreichen. Das UAV-System für die Untersuchungen wurde md4-200 bei Microdrones erfunden. Die md4-200 ist mit einer Kompaktkamera, einer Pentax Optio A40 Digitalkamera, ausgestattet. Zwei Kamerakalibrierungsmethoden sind gemacht worden, um die inneren Kamera Parameter kennen zu können. Eine Laborkalibrierung mit einem Testfeld und eine Testfeldkalibrierung sind ausgerichtet worden. Photomodeler Scanner software ist für die Kamerakalibrierungsprozesse in beiden Test ausgewählt worden. Der Laborkalibrierungsprozess war vollautomatish. Die Bilder sind mit längerer Brennweite gemacht worden. Die Bilder des Testfeld...

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Investigation of the Kodak DCS460 digital camera for small-area mapping

Cited by 30 publications

References 10 publications

Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools

Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools

Image Sources for Informal Settlement Management

Digital Camera Calibration Using Images Taken From an Unmanned Aerial Vehicle

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