# GIS
# 计算 LineString 精确长度
# CCW 和 CW 的含义 (opens new window)
Two-dimensional rotation can occur in two possible directions. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back up to the top. The opposite sense of rotation or revolution is (in Commonwealth English) anticlockwise (ACW) or (in North American English) counterclockwise (CCW).[1]
specifically 0 for points, 1 for lines, 2 for areas. Then, the domain of the model is {0,1,2,F}.
self-intersection (opens new window)
A proper intersection is an intersection which is interior to at least two line segments. Note that a proper intersection is not necessarily in the interior of the entire Geometry, since another edge may have an endpoint equal to the intersection, which according to SFS semantics can result in the point being on the Boundary of the Geometry.
A proper interior intersection is a proper intersection which is not
contained in the set of boundary nodes set for this SegmentIntersector.
improper intersections
e.g. where one or other of the geometrys has a vertex at the intersection point
# Polygonal chain intersection
the PCI problem by considerin gthe two major differences between the LSI and PCI problems
(1) theline-segments in a polygonal chain are connected and linearly ordered, and this additional information may beused to improve the efficiency and
(2) a point shared bytwo adjacent line-segments in a polygonal chain shouldnot be reported as an intersection
Geometric intersection algorithms for polygons use line segmentintersection (LSI) and point-in-polygon (PNP) operations as build-ing blocks
minimum bounding rectangle (MBR)
Tile matrix sets (opens new window)
pros and cons of TIFF files (opens new window)
# GeoTiff 操作
展示geotiff信息
gdalinfo -stats -hist file.tif
(tiffdump 和 tiffinfo) 无法识别一些geotiff的tag
apt install libtiff-tools 可以安装 tiffinfo,tiffdump