Measurement Accuracy of Center Location of a Circle by Centroid Method

Matsuoka, Ryuji; Shirai, Naoki; Asonuma, Kazuyoshi; Sone, Mitsuo; Sudo, Noboru; Yokotsuka, Hideyo

doi:10.1007/978-3-642-24393-6_25

Cited by 7 publications

(6 citation statements)

References 4 publications

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“…In our case, the image features corresponding to the LEDs consist only of a few pixels and are blurry because of motion. Thus, with classical template matching or centroid methods [28] it is difficult to achieve a precision better than one pixel.…”

Section: Contributionsmentioning

confidence: 99%

Photometric Long-Range Positioning of LED Targets for Cooperative Navigation in UAVs

Jospin

Stoven-Dubois

Cucci

2019

Drones

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Autonomous flight with unmanned aerial vehicles (UAVs) nowadays depends on the availability and reliability of Global Navigation Satellites Systems (GNSS). In cluttered outdoor scenarios, such as narrow gorges, or near tall artificial structures, such as bridges or dams, reduced sky visibility and multipath effects compromise the quality and the trustworthiness of the GNSS position fixes, making autonomous, or even manual, flight difficult and dangerous. To overcome this problem, cooperative navigation has been proposed: a second UAV flies away from any occluding objects and in line of sight from the first and provides the latter with positioning information, removing the need for full and reliable GNSS coverage in the area of interest. In this work we use high-power light-emitting diodes (LEDs) to signalize the second drone and we present a computer vision pipeline that allows to track the second drone in real-time from a distance up to 100 m and to compute its relative position with decimeter accuracy. This is based on an extension to the classical iterative algorithm for the Perspective-n-Points problem in which the photometric error is minimized according to a image formation model. This extension allow to substantially increase the accuracy of point-feature measurements in image space (up to 0.05 pixels), which directly translates into higher positioning accuracy with respect to conventional methods.

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Section: Contributionsmentioning

confidence: 99%

Photometric Long-Range Positioning of LED Targets for Cooperative Navigation in UAVs

Jospin

Stoven-Dubois

Cucci

2019

Drones

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“…One of the most influential factors would be quantization in creating a digital image. As for a circle, the author reported an investigation on the effect of quantization on V() by WCM (Matsuoka et al, 2011). The results of the investigation showed that V() would oscillate in an approximate 0.5 pixel cycle in radius for any quantization level and decrease as a quantization level increases.…”

Section: Measurement Of the Centre Location Of An Ellipsementioning

confidence: 99%

Measurement Precision and Accuracy of the Centre Location of an Ellipse by Weighted Centroid Method

Matsuoka

2015

ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Circular targets are often utilized in photogrammetry, and a circle on a plane is projected as an ellipse onto an oblique image. This paper reports an analysis conducted in order to investigate the measurement precision and accuracy of the centre location of an ellipse on a digital image by an intensity-weighted centroid method. An ellipse with a semi-major axis a, a semi-minor axis b, and a rotation angle  of the major axis is investigated. In the study an equivalent radius r = (a )1/2 is adopted as a measure of the dimension of an ellipse. First an analytical expression representing a measurement error ( x ,  y ) is obtained. Then variances V x of  x are obtained at 1/256 pixel intervals from 0.5 to 100 pixels in r by numerical integration, because a formula representing V x is unable to be obtained analytically when r > 0.5. The results of the numerical integration indicate that V x would oscillate in a 0.5 pixel cycle in r and V x excluding the oscillation component would be inversely proportional to the cube of r. Finally an effective approximate formula of V x from 0.5 to 100 pixels in r is obtained by least squares adjustment. The obtained formula is a fractional expression of which numerator is a fifth-degree polynomial of {r−0.5×int(2r)} expressing the oscillation component and denominator is the cube of r. Here int(x) is the function to return the integer part of the value x. Coefficients of the fifth-degree polynomial of the numerator can be expressed by a quadratic polynomial of {0.5×int(2r)+0.25}.

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“…In recent years the correction of colour aberrations becomes indispensable for highly accurate measurement (Kaufmann and Ladstädter, 2005, Luhmann et al, 2006a, Mallon and Whelan, 2007, Hattori et al, 2011. In the era of digital photogrammetry the fact that sampling and quantization in creating a digital image affect the accuracy of image measurement using digital images was reported (Matsuoka et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Eccentricity on an Image Caused by Projection of a Circle and a Sphere

Matsuoka¹,

Maruyama²

2016

ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Circular targets on a plane are often utilized in photogrammetry, particularly in close range photogrammetry, while spherical targets are sometimes utilized in industrial applications. Both a circle and a sphere are projected as an ellipse onto an image. There is an eccentricity on an image between the centre of the projected ellipse and the projected location of the centre of a circle or a sphere. Since only the centre of the projected ellipse is measured, the correction of the eccentricity is considered to be necessary for highly accurate measurement. This paper shows a process to derive general formulae to calculate an eccentricity of a circle and a sphere using the size and the location of a circle or a sphere, and the focal length, the position and the attitude of a camera. Furthermore the paper shows methods to estimate the eccentricity of a circle and a sphere from the equation of the projected ellipse of a circle or a sphere on an image.

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Measurement Accuracy of Center Location of a Circle by Centroid Method

Cited by 7 publications

References 4 publications

Photometric Long-Range Positioning of LED Targets for Cooperative Navigation in UAVs

Photometric Long-Range Positioning of LED Targets for Cooperative Navigation in UAVs

Measurement Precision and Accuracy of the Centre Location of an Ellipse by Weighted Centroid Method

Eccentricity on an Image Caused by Projection of a Circle and a Sphere

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