XXII ISPRS Congress 2012: Technical Commission VIII

Shortis, M.; Shimoda, H.; Cho, K.

Bibliographic data

Multivolume work

Persistent identifier:: 1663813779

Title:: XXII ISPRS Congress 2012

Sub title:: Melbourne, Australia, 25 August-1 September 2012

Type of content:: Konferenzschrift

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663813779

Reihe:: ISPRS archives

Language:: English

Additional Notes:: Kongress-Thema: Imaging a sustainable future

Editor:: International Society for Photogrammetry and Remote Sensing

Author:: International Society for Photogrammetry and Remote Sensing, 22.; 2012; Melbourne

Document type:: Multivolume work

Volume

Persistent identifier:: 1663822514

Title:: Technical Commission VIII

Scope:: 590 Seiten

Type of content:: Konferenzschrift

DOI:: 10.14463/KXP:1663822514

Year of publication:: 2014

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663822514

Illustration:: Illustrationen, Diagramme

Reihe:: ISPRS archives (volume 39, B8 (2012))

Signature of the source:: ZS 312(39,B8)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist ermittelt.; Literaturangaben

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

Editor:: Shortis, M.; Shimoda, H.; Cho, K.

Editor:: International Society for Photogrammetry and Remote Sensing

Author:: International Society for Photogrammetry and Remote Sensing, 22.; 2012; Melbourne

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:: [VIII/6: Agriculture, Ecosystems and Bio-Diversity]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: ESTIMATION OF VEGETATION HEIGHT THROUGH SATELLITE IMAGE TEXTURE ANALYSIS Z. I. Petrou, C. Tarantino, M. Adamo, P. Blonda, M. Petrou

Document type:: Multivolume work

Structure type:: Chapter

bits with 0 values are likely to be found in the former numbers, because of the existence of more surrounding pixels having the same intensity as the central one. However, 0 values dominate also in case of heterogeneous neighborhoods having a central pixel with larger intensity values than its surrounding pixels. To counterbalance this drawback, a variation of the local binary patterns algorithm is also tested, termed local ternary patterns (Tan and Triggs, 2007), with the incorporation of a third value in labeling neighboring pixels. In this case, if a pixel intensity dif- fers within a predefined range +d from the central pixel it takes value 1. If it is larger or smaller than the central pixel by more than d, it takes value 2 or 0, respectively. In addition, depending on the value of range d, the measure may handle noise and poten- tial inaccuracies of the data, up to a certain degree. The created number is now expressed in the ternary system instead of the bi- nary, i.e. having number three as basis. The more homogeneous textures are expected to be represented by numbers close to the one having all its bits equal to 1. Following the same notion, another variation can be introduced from the combination of local binary and ternary patterns, by as- signing value 0 to the pixels whose intensity differs less than a range +d from the central one and value 1 otherwise. In this measure, the more homogeneous a patch, the smaller its measure value is expected to be. 4 RESULTS AND DISCUSSION To evaluate the performance of the proposed measures in esti- mating vegetation height and discriminating between LPH/MPH and TPH habitat classes, different versions of the measures were applied to all patches of low/mid and tall phanerophytes on Le Cesine site, extracted from the available habitat map, for each band of the Quickbird image. 52 LPH/MPH and 99 TPH patches were totally considered. For each patch, each measure was calcu- lated on a per pixel basis and then averaged for the pixels of the patch. The discriminatory power of each measure for a specific band was tested in two ways. At first, Student's t-tests were applied to compare the measure values for LPH/MPH and TPH patches. Under the null-hypothesis that the values of LPH/MPH and TPH patches come from the same distribution, one-tailed tests were performed to assess our expectation that LPH/MPH patch values are significantly smaller than TPH ones. In addition, the ability of the measures to create correct classification of the LPH/MPH and TPH patches was evaluated with a decision tree classifier based on the CART (Classification And Regression Tree) methodology (Breiman et al., 1984). A CART tree consists of binary nodes, each one examining whether the value of a patch for a specific measure is smaller or larger than a certain value. In addition, at the end of the training process, CART trees are pruned, i.e. the number of their nodes is reduced to a certain degree, in order to increase their generalization performance with data non belong- ing to the training set. Table 1 summarizes the results of the evaluation of the texture analysis measures. Different parameters were tested for each ap- proach, resulting in different instances of each measure. À clas- sification tree was created for each measure in each band. For the training of each tree a random subset of 30 LPH/MPH and 50 TPH patches was selected; the non-selected patches were used for testing the classification accuracy of the tree. The ratio of the correctly classified patches to the total number of the test set patches is recorded in the table. In addition, the p-value resulting International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012 XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia from each t-test is drawn, indicating the probability that a differ- ence between the LPH/MPH and TPH mean values as large as or larger than the one observed can occur, assuming that the null hy- pothesis is true. The lower the p-value, the larger the probability that the null hypothesis is wrong and, thus, the measure values for the LPH/MPH patches do not come from the same distribu- tion and are significantly smaller than the TPH ones. Two versions of the local energy measure appear in Table 1: in LEI, a window of 3 x 3 pixels around each pixel was used for the calculation of the variance, while in LE2, a window of 5 x 5 pixels was used. In LH1 and LH2 versions, the local entropy was calcu- lated in 9 x 9 pixel windows. The data were quantized in 8 bins for each individual window in LH1, while in LH2 quantization in 8 bins was applied to the whole region from the beginning. A quantization in 8 bins of the whole region and a selection of 9 x 9 pixel windows as the small ones, were applied in ‘LHR’ versions of the calculation of the local entropy ratio. In LHR1 and LHR2 the small windows were included in the calculation of the local entropy of the large windows. In LHR1, 13 x 13 pixel windows were selected as the large ones, while in LHR2 their dimensions were 21 x 21 pixels. In LHR3 and LHR4, the same parameters as in LHR1 and LHR2, respectively, were used, with the difference that the inner window pixels were excluded from the calculation of the local entropy of the outer windows. Rotation invariant and rotation variant local binary patterns were calculated for radius 1 in LBP1 and LBP2, respectively. In LBP3 and LBP4, the same parameters were used, with the radius changing to 2. The ‘LTP’ and ‘LTBP’ versions were the same as the respective ‘LBP’ ones, with the only difference being that the ternary system and the modified binary approach were adopted, respectively. As observed, most p-values resulting from the t-tests are signif- icantly smaller than the 5% level of significance usually used in assessing the null hypothesis (Chatfield, 1983). This provides a strong evidence against the null hypothesis that the mean values of the measures for LPH/MPH and TPH patches are almost the same and strongly supports our theoretical assumption that the values of the LPH/MPH patches are significantly smaller than the TPH ones. The smaller the p-value for a specific measure instance, the higher the confidence that this instance can lead to clear discrimination of low/mid and tall phanerophyte patches. As far as the used Quickbird bands is concerned, it is observed that all visible ones performed almost equally well and outper- formed the near-infrared (NIR) band in discriminatory power. Among them, values extracted from the green band, seem to pro- vide better results for most measures. Regarding the measures tested, the local ternary patterns, ‘LTP’, and the modified local binary patterns, ‘LTBP’, instances seem to outperform all other measures in the visible bands, with the latter appearing slightly better. The local entropy ratio measure, on the other hand, ap- pears robust in all bands and provides satisfactory results even in the NIR band, especially in the implementations where the outer window is significantly larger than the inner one, LHR2 and LHRA. The top performing measures as far as the t-test is concerned, include the implementation of the rotation invariant local ternary patterns with radius 1, LTP1, as well as the modified rotation vari- ant local binary patterns approach with radius 2, LTBP4, both cal- culated in the green band, with p-values of the order of magnitude of 107??, As expected, these results are in accordance with the CART classification assessment results, where LTP1 and LTBP4 instances in the green band present the highest rates in correctly classifying LPH/MPH and TPH patches based on their height. The instance that outperforms all others in classification accu- racy is the modified rotation variant local binary pattern approach with r: ing an size W and bl ratio 2 from | almos for wl Simil: modif formii classi In gen sificat the lo tion a not al into ti influe degre: Consi of dat a seri homo appro veget appez neous grour Local the b. variat for al eral, ; forme

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