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Modern Geomatics Technologies and Applications

detecting direct lines. This algorithm works by transferring the coordinate system from the Cartesian space to the polar space.
Crops are usually planted directly with farming systems, but poor germination and other factors cause gaps and discontinuities
in the lines. Therefore, Hough's algorithm operates independently of line discontinuities and reconstructs crop lines. The Hough
transform is applied directly to the edge image to detect a crop line and reconstruct direct lines from the extracted edges [9]. The
outputs of the first phase are shown in Figure 2.

Fig 2: Work process in the first phase
 Filtering Lines by prevailing slope
However, after determining and identifying the initial crop lines, it is necessary to filter, extract and remove the wrong
lines. Considering the regular planting of the crop, it can be said that one of the criteria for removing lines is the difference in
slope with other lines. Figure (3) shows the slope histogram of the lines extracted in the previous step for a small tile of the
image. By determining the predominant slope of the lines, it is determined that the slope of 96% of the lines will be between
15.4 and 20.8, so lines that have a slope outside this range will be removed.

Fig 3: Filtering lines by prevailing slops. (A) Crop lines before filtering. (B)Histogram of slops. (C) Crop lines after filtering
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