XVIIIth Congress: XVIIIth Congress

kraus, karl; waldhäusl, peter

Bibliographic data

Multivolume work

Persistent identifier:: 1667435949

Title:: XVIIIth Congress

Sub title:: Vienna, Austria 1996

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667435949

Language:: English

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1667437070

Title:: XVIIIth Congress

Scope:: 230 Seiten

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667437070

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(31,B1)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist anhand des Copyrightjahrs ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: ON THE AUTOMATED ASSESSMENT OF GEOMETRIC SCANNER ACCURACY R. Seywald

Document type:: Multivolume work

Structure type:: Chapter

6 AUTOMATED ANALYSIS When locating the center of measuring marks with sub-pixel accuracy a wide range of techniques is proposed and these can be grouped as centroiding, correlation, edge analysis and shape based techniques [Trinder, 1989] [West, 1990]. Auto- mated measurement is possible with an accuracy of better than + 0.1 pixels. With the scanner evaluation system the center of circular digital dots and other symmetric measuring marks can be found automatically with subpixel accuracy by means of a weighted center finding algorithm [Trinder, 1989]. According to the former investigations with a target diameter of 4 pixels of [Maalen, 1993] the automated algorithms de- liver the best results. Target sizes of less than 4 pixels have to be avoided due to large deterioration of precision, whereas the precision is slightly lower but sufficient for more than 4 pixels of diameter. The dynamic range of the measuring marks will not significantly influence the accuracy of centering as long it has more than 2 bits of radiometric resolution . Thresh- olding can be used to isolate the background from the target which results in a certain loss of radiometric range. Machine centering at suitable measuring marks is preferred since in the long term it offers higher accuracy, independent of the operators skill and of the exact diameter of the targets. Fi- nally, of course, it will also be faster to center automatically by machine than to accomplish this by hand. 7 EXPERIMENTAL RESULTS Various investigations of geometric accuracy on different scanners from the low price DTP scanner to the high per- formance film scanner were performed by means of the SCANEVAL system. Here the individual manufactorers and scanner models are kept anonymous to emphasize the test technology, not the specific test result. Typical geometric errors according to the scanners scanning principle can be obtained by scanning and analyzing the geometric accuracy target. 7.1 Single line CCD Scanner Figure 3 shows the error vectors for a DTP scanner using single line CCD technology. The change of vector orientation in the scanning direction indicates that the speed of the CCD linear array is not stable when moving over the scanning area. Consequently the resulting real pixel size is varying over the scanning region and is directly proportional to residual varia- tions. 7.2 Multiple swath line CCD scanner The residual error vectors obtained after an affine transforma- tion for a widely distributed high performance flatbed scanner can be seen in Figure 4. In this case adjacent scanning swaths are stitched together to one large digital image. The changing vector orientations in scanning direction indicate mechanical misalignment of the line array CCD when scanning neighbor- ing swaths. 7.3 Square array CCD scanner The residual error vectors for a high performance film scanner working with the square array CCD principle are shown in Figure 5. To avoid geometric errors adjacent tiles have to be assembled geometrically and radiometrically. 184 lle: pat gri ; .B2 pixel / 34.66 um, ^ Resid.foct- 54 mox. deviation horizontal = 1.88 pixel / 79.50 um mox. deviation vertical = 2.04 pixel / 86.31 um, Pixelsize= 42.3 um Figure 3: Residual error vectors when evaluating a test area of 11cm x 16 cm, including 19 x 30 measuring marks. Here the scanning resolution is 600dpi (42um). The r.m.s. deviation from ideal mark position obtained by affine transform is + 35 pm. Maximum deviations are 74 um horizontally and 87 pm vertically. error vector magnification: 54; scan direction: left to right; 1 A 3d pef N fs + OR NT sonia na a ee Lys I : A uiu ; Uu T J y s. + i CE ais i SH Es d AN 17 anid qo s "S Le eid ito ; pobres ra dm TR TR: Ee A 5h. } 7 . | For 2 Je ] QE s SERA ] ] 4 = | ES TP Ly CX Du / ku / E j yi | 4 id YN s OM: A d zx 7 / / ja ed | ui. J A ; j ssa iy. ide rid Cory 1 % œ 5 SAI a gc | ig 1 xd PN $e j UY ) v AL Ln T pil Fh t leg ow ep epo és A ada - File: pstgrid2— 1.tst.tiff, RMS- Q82 pixel / 616 pm, Resld factz 332 mox. deviation horizontal — 1.38 pixel / 10.18 um mox. deviation vertical = 2.00 pixel / 15.02 um, Pixelsize= 7,5 jam Figure 4: A subsection of resulting residual error vectors when evaluating a test area of 11cm x 16 cm, including 19 x 30 mea- suring marks. Orientation of error vectors changes in neigh- bored measuring mark columns. This leads to the assumption that adjacent scanning swaths are misaligned. Affine trans- form; Pixelsize=7.5um; RMS error==4 6.2um; error vector magnification: 332; swath scan direction: top to bottom. International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996 The: vxe max. de mux, de Figu ray ror \ tiles dire Pixe ficat 7.4 Tab ber bes mak by L tion inve the Tat of 1 forr abc It is in t

Access restriction

Copyright

fullscreen: XVIIIth Congress (Part B1)

Multivolume work

Volume

Chapter

Table of contents

Cite and reuse

Volume

Chapter

Image

Image fragment

Citation links

Citation recommendation