EP1299760A1 - Procede de mise au point automatique pour des telescopes d'appareils d'arpentage - Google Patents

Procede de mise au point automatique pour des telescopes d'appareils d'arpentage

Info

Publication number
EP1299760A1
EP1299760A1 EP01960486A EP01960486A EP1299760A1 EP 1299760 A1 EP1299760 A1 EP 1299760A1 EP 01960486 A EP01960486 A EP 01960486A EP 01960486 A EP01960486 A EP 01960486A EP 1299760 A1 EP1299760 A1 EP 1299760A1
Authority
EP
European Patent Office
Prior art keywords
maximum
kkf
signal
signal amplitude
local
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01960486A
Other languages
German (de)
English (en)
Inventor
Thomas Marold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Trimble Jena GmbH
Original Assignee
ZSP Geodaetische Systeme GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ZSP Geodaetische Systeme GmbH filed Critical ZSP Geodaetische Systeme GmbH
Publication of EP1299760A1 publication Critical patent/EP1299760A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C15/00—Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
    • G01C15/002—Active optical surveying means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C1/00—Measuring angles
    • G01C1/02—Theodolites
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/28—Systems for automatic generation of focusing signals
    • G02B7/36—Systems for automatic generation of focusing signals using image sharpness techniques, e.g. image processing techniques for generating autofocus signals

Definitions

  • the invention relates to a method for autofocusing, in particular for telescopes of surveying devices, and is suitable for image sensors that resolve the image signal into individual picture elements (pixels), such as CCD lines and matrices and CMOS image sensors.
  • pixels such as CCD lines and matrices and CMOS image sensors.
  • DE-OS 1 96 1 4 235 describes an auto focus for a level. Additional optics located behind the image plane serve to capture the focus by means of two imaging lenses that generate object images on two line sensors. Means for detecting the focusing lens position are also required.
  • DE-OS 1 95 49 048 is to be seen, which uses a beam splitter to generate a plane for the focus detection system that is equivalent to the image plane.
  • This solution has the disadvantage that it cannot be easily transferred to a digital level.
  • JP-OS 4-93 71 1 contains an autofocus for a CCD camera connected to a tachymeter telescope via a beam splitter. A focusing lens is adjusted so that the image size of the imaged object is minimal. This solution also does not necessarily ensure optimal image sharpness, since the minimum can be relatively wide and is therefore difficult to grasp.
  • US 54 81 329 describes an autofocus device with an additional image on the image plane on four sensors and correlation of the opposite, resulting images. The sum of the difference between neighboring pixels is taken as the contrast value. Depending on the success, further filters are available for other spatial frequencies. Depending on whether an object produces a high-contrast or low-contrast image, the proportion of constant light is removed completely or incompletely. The required additional optics are disadvantageous and complex in this device.
  • the image contrast is at a maximum. From DE 1 95 00 81 7 it is also known to find edges as objects of greatest contrast in the image as a local maximum or minimum of the cross-correlation function (KKF) of a few pixels of the image content with an ideal edge.
  • KF cross-correlation function
  • the focusing path up to the next measurement is determined as a product of the ratio of the maximum signal to the local signal amplitude, the focus position in relation to the position when focusing on infinity and a constant.
  • FIG. 2 shows the signal representation of a CCD line with defocused image
  • FIG. 3 shows the signal representation of a CCD line with the image focused
  • FIG. 4 shows a flowchart for the first part of the autofocus algorithm described in the example
  • FIG. 5 shows a flowchart for the second part of the autofocus algorithm described in the example.
  • FIG. 1 shows the measurement image of the CCD line of a digital level with complete defocusing.
  • the x-axis 1 continuously shows the pixel number i from 0 to 1,799.
  • the brightness of the respective pixel Yj is plotted in arbitrary units on the y-axis 2.
  • the value 255 means no signal (black), the value 0 means maximum signal (white), which results in a negative representation.
  • the measurement images according to FIGS. 1 to 3 were taken with a digital level in which, due to the design, only a little light can reach the beginning or the end of the CCD line. In principle, it is of course also possible to determine the dark signal from a separate measurement.
  • the brightest point is at pixel 720.
  • the signal Ymin is used in a known manner for exposure control.
  • ß be kept within certain limits. For example, it must not become zero because the CCD line is then overexposed.
  • the first value essential for focusing that is obtained from the measurement image is the maximum signal S]:
  • FIG. 2 shows a signal representation of a CCD line with a defocused image. A certain picture content is already recognizable here.
  • MPX center pixel
  • the local signal amplitude S2 is calculated from the monotonically falling or rising signal up to the next local maximum Ylmax and minimum Y
  • Imax the local maximum
  • Imin the local minimum
  • the first relationship (formula) to focus is as follows:
  • Focusing path (Si / S2) »focus position • constant (7)
  • S, / S2 is limited to a maximum value, e.g. 4 Fig. 4).
  • rule (7) does not include the signal amplitude but the ratio 5, 7 52 has the advantage that rule (7) is independent of the amplitude. It can therefore be used before an optimal exposure control has been made. The calculations and changes in the focus position of the links for the autofocus can thus already take place during the exposure control.
  • FIG. 3 shows the same object as in FIGS. 1 and 2, but in a focused state.
  • the measurement curve 20 contains dark areas 21 and bright areas 22, which are separated by edges 23. The edges only extend over a few pixels of the image. The pixels 24, 25, 26 and 27 of the edge 23 are shown in FIG. 3.
  • Pixels 24 to 27 have the signals in this order:
  • the third function that is essential for the focusing process is the cross-correlation function (KKF), each consisting of four pixels and an ideal dark-light edge with the signals (+1; + l; -l; -l).
  • KF cross-correlation function
  • KKF (i) Yj + Yj + i - Yj + 2 - Yi + 3 (8)
  • KKF (860) 1 09 results.
  • the KKF is formed pixel by pixel.
  • edges in the measurement image which lie in the region of the pixels Yj + i and Yj + 2, respectively.
  • the exact position is then determined by interpolation. It is essential for the focusing process that the KKF is a measure of the image contrast.
  • a reference function can be formed from the KKF maxima, which allows statements to be made about the state of focus. It is expedient and easiest to use the maximum value of the KKF in the entire image field as a reference function. With a little more effort, the mean value from the local maxima of the KKF could also be used as a reference function.
  • the reference function thus formed is referred to below as KKF MAX.
  • the further focusing process consists of maximizing the KKF MA ⁇ / S 2 function. Depending on the size of the KKF MA ⁇ / S 2 function, it is advisable to either set the focusing path to twice the depth of focus as long as KKF MA ⁇ / S 2 ⁇ 0.5 is. If the value 0.5 is exceeded, the focusing path is limited to the depth of field until the next measurement.
  • the sequence of the focusing process is shown as a flow chart in FIG. 5.
  • the focusing path can be measured or also by a suitable control of the focusing motor, e.g. a stepper motor can be set with sufficient accuracy without measurement.
  • a suitable control of the focusing motor e.g. a stepper motor can be set with sufficient accuracy without measurement.
  • FIGS. 4 and 5 The rules regarding focusing are summarized in FIGS. 4 and 5.
  • Fig. 4 shows that rule (7) is applied until either the focus position is ⁇ 0.1 or Si / S2 falls below a value of 1.4.
  • Fig. 5 shows that if one of the above conditions is met, KKF MA ⁇ / S2 is formed.
  • the step size is limited to the depth of field as soon as KKF MA ⁇ / S2> 0.5. Subsequently - "t retraction up to the maximum KKF, M, AX / S2 * - '
  • the invention is not limited to the example above.
  • the for decision The selected constants can assume other values that are optimally adapted to the respective optical system.
  • the step sizes indicated in FIG. 5 for the focusing can also assume other values, such as the whole and half the depth of focus.
  • the KKF another strongly contrast-dependent function can be used. It is also possible instead of CCF MA ⁇ / S2 as decision J skriterium the function CCF. M, X A ⁇ V to use, 'only must then be eschreibt g 3 that the exposure does not change anymore during the focusing operation.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Optics & Photonics (AREA)
  • Automatic Focus Adjustment (AREA)
  • Focusing (AREA)

Abstract

Procédé de mise au point automatique, en particulier pour des télescopes d'appareils d'arpentage qui sont équipés de capteurs d'images restituant le signal d'image en éléments d'image individuels (pixels), tels que des lignes et / ou matrices à dispositif à couplage de charge, ainsi que de capteurs d'images CMOS. A partir du pixel qui est le plus proche de l'axe optique, l'amplitude locale de signal est calculée sur la base du signal tombant ou montant de manière monotone jusqu'au prochain maximum ou minimum local. Tant que cette amplitude locale de signal est considérablement inférieure au signal maximal et que l'élément de mise au point de l'objectif du télescope se trouve en position de mise au point pendant de courts laps de temps, cet élément de mise au point est déplacé sur de grands pas de progression. La longueur des pas de progression est raccourcie selon la grandeur de l'amplitude locale de signal par rapport au signal maximal et selon la position de l'élément de mise au point dans la zone de portées plus grandes. Pour une certaine grandeur de l'amplitude locale du signal par rapport au signal maximal, des fonctions de corrélation croisée (KKF) sont en outre formées à partir de quelques pixels du signal et de structures de comparaison appropriées. Pour un certain rapport entre la fonction de référence formée à partir des KKF et l'amplitude locale du signal, un pas de progression comparable à la définition en profondeur optique est sélectionné et mis au point sur le maximum des KKF.
EP01960486A 2000-07-10 2001-07-10 Procede de mise au point automatique pour des telescopes d'appareils d'arpentage Withdrawn EP1299760A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10033483 2000-07-10
DE10033483A DE10033483C1 (de) 2000-07-10 2000-07-10 Verfahren zur Autofokussierung für Fernrohre von Vermessungsgeräten
PCT/EP2001/007931 WO2002005005A1 (fr) 2000-07-10 2001-07-10 Procede de mise au point automatique pour des telescopes d'appareils d'arpentage

Publications (1)

Publication Number Publication Date
EP1299760A1 true EP1299760A1 (fr) 2003-04-09

Family

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EP01960486A Withdrawn EP1299760A1 (fr) 2000-07-10 2001-07-10 Procede de mise au point automatique pour des telescopes d'appareils d'arpentage

Country Status (4)

Country Link
US (1) US6927376B2 (fr)
EP (1) EP1299760A1 (fr)
DE (1) DE10033483C1 (fr)
WO (1) WO2002005005A1 (fr)

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Publication number Priority date Publication date Assignee Title
JP4201924B2 (ja) * 1999-06-28 2008-12-24 株式会社 ソキア・トプコン 測量機の自動焦点機構
DE10033483C1 (de) 2000-07-10 2002-01-03 Zsp Geodaetische Sys Gmbh Verfahren zur Autofokussierung für Fernrohre von Vermessungsgeräten
DE10349030B4 (de) * 2003-10-13 2005-10-20 Gkn Driveline Int Gmbh Axialverstellvorrichtung
DE102005053555B3 (de) * 2005-11-08 2007-08-02 Gkn Driveline International Gmbh Kugelrampenanordnung mit variabler Steigung der Kugelrillen
CN101501445B (zh) 2006-08-01 2012-06-27 特里伯耶拿有限公司 电子找平设备和方法
US7627429B2 (en) * 2006-09-15 2009-12-01 Schlumberger Technology Corporation Method for producing underground deposits of hydrocarbon from an earth formation using fault interpretation including spline fault tracking
EP3839424A1 (fr) 2019-12-19 2021-06-23 Leica Geosystems AG Télescope de relevé géodésique comportant une mise au point du capteur d'image

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JPS5078321A (fr) * 1973-11-09 1975-06-26
GB2003692B (en) 1977-09-02 1982-08-11 Olympus Optical Co Method for detecting a focalisation or in-focussed-condition of an optical system
JPS5616806A (en) 1979-07-20 1981-02-18 Hitachi Ltd Surface roughness measuring unit
US4371866A (en) * 1980-11-21 1983-02-01 The United States Of America As Represented By The Secretary Of The Army Real-time transformation of incoherent light images to edge-enhanced darkfield representation for cross-correlation applications
DE3339970A1 (de) 1983-11-04 1985-05-15 Karl Süss KG, Präzisionsgeräte für Wissenschaft und Industrie GmbH & Co, 8046 Garching Einrichtung zum automatischen fokussieren von optischen geraeten
US4639587A (en) * 1984-02-22 1987-01-27 Kla Instruments Corporation Automatic focusing system for a microscope
US4677286A (en) * 1985-02-14 1987-06-30 Quantronix Corporation Method and apparatus for autofocusing a microscope
JPH0610694B2 (ja) * 1985-04-12 1994-02-09 株式会社日立製作所 自動焦点合せ方法及び装置
US4804831A (en) 1985-10-30 1989-02-14 Canon Kabushiki Kaisha Focus detecting apparatus independent of object image contrast
JPH0738046B2 (ja) 1987-03-30 1995-04-26 新王子製紙株式会社 内部的構造を有する半透光性シート状試料の表面検査装置
US4945220A (en) 1988-11-16 1990-07-31 Prometrix Corporation Autofocusing system for microscope having contrast detection means
JP3444551B2 (ja) * 1994-05-11 2003-09-08 オリンパス光学工業株式会社 カメラの焦点検出装置
JP3708991B2 (ja) * 1994-12-28 2005-10-19 ペンタックス株式会社 インナーフォーカスの望遠鏡
DE19500817C1 (de) * 1995-01-13 1996-02-22 Zeiss Carl Jena Gmbh Verfahren zur Bestimmung von Kantenpositionen
DE19614235C2 (de) * 1995-04-10 2001-06-28 Asahi Optical Co Ltd Vermessungsinstrument mit Autofokussystem
JP2000125177A (ja) * 1998-10-12 2000-04-28 Ricoh Co Ltd 自動合焦装置
DE10033483C1 (de) 2000-07-10 2002-01-03 Zsp Geodaetische Sys Gmbh Verfahren zur Autofokussierung für Fernrohre von Vermessungsgeräten

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Also Published As

Publication number Publication date
DE10033483C1 (de) 2002-01-03
WO2002005005A1 (fr) 2002-01-17
US20030089837A1 (en) 2003-05-15
US6927376B2 (en) 2005-08-09

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