如何使用(Ruby)RGeo转换(非项目)坐标 [英] How Can I Use (Ruby) RGeo to Transform (Unproject) Coordinates
问题描述
那里的回应使我进入了正确的道路，但我仍然无法解决我的问题.
The response there started me on [what I think is] the right track, but I still haven't been able to solve my problem.
One issue is that I haven't found the correct projection yet: https://gis.stackexchange.com/questions/13330/how-can-i-correctly-transform-unproject-from-lcc
gis站点上的问题已得到解答，并且我能够使用PROJ命令行工具cs2cs重现正确的转换.看起来像这样:
That question on the gis site has been answered, and I was able to reproduce a correct transformation using the PROJ command line tool cs2cs. It looks like this:
larry$ cs2cs -f "%.8f" +proj=lcc +lat_1=37.06666666666667 +lat_2=38.43333333333333 +lat_0=36.5 +lon_0=-120.5 +x_0=2000000 +y_0=500000.0000000002 +ellps=GRS80 +datum=NAD83 +to_meter=0.3048006096012192 +no_defs +to +proj=lonlat +datum=WGS84 +ellps=WGS84
6011287.4999795845 2100857.2499904726
-122.40375492 37.74919006 0.00000000
现在，我进行了正确的转换，我可以使用RGeo以简单的形式尝试相同的事情:
Now, that I had the correct transformation, I was able to try the same thing in a simple form using RGeo:
ruby-1.9.2-p180 :001 > projection_str = ' +proj=lcc +lat_1=37.06666666666667 +lat_2=38.43333333333333 +lat_0=36.5 +lon_0=-120.5 +x_0=2000000 +y_0=500000.0000000002 +ellps=GRS80 +datum=NAD83 +to_meter=0.3048006096012192 +no_defs'
=> " +proj=lcc +lat_1=37.06666666666667 +lat_2=38.43333333333333 +lat_0=36.5 +lon_0=-120.5 +x_0=2000000 +y_0=500000.0000000002 +ellps=GRS80 +datum=NAD83 +to_meter=0.3048006096012192 +no_defs"
ruby-1.9.2-p180 :002 > projection = RGeo::CoordSys::Proj4.new(projection_str)
=> #<RGeo::CoordSys::Proj4:0x805cba18 " +proj=lcc +lat_1=37.06666666666667 +lat_2=38.43333333333333 +lat_0=36.5 +lon_0=-120.5 +x_0=2000000 +y_0=500000.0000000002 +ellps=GRS80 +datum=NAD83 +to_meter=0.3048006096012192 +no_defs +towgs84=0,0,0">
ruby-1.9.2-p180 :003 > desired_str = '+proj=lonlat +datum=WGS84 +ellps=WGS84'
=> "+proj=lonlat +datum=WGS84 +ellps=WGS84"
ruby-1.9.2-p180 :004 > desired = RGeo::CoordSys::Proj4.new(desired_str)
=> #<RGeo::CoordSys::Proj4:0x805271ac " +proj=lonlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0">
ruby-1.9.2-p180 :005 > RGeo::CoordSys::Proj4::transform_coords(projection, desired, 6011287.4999795845, 2100857.2499904726 )
=> [-140.92282523143973, 30.16981659183029]
- 为什么RGeo和cs2cs的结果不同?
- 一旦我可以使RGeo执行正确的翻译，有什么办法可以创建适当的工厂来转换完整的Geometry(而不是点)?
- 是否可以使用命令行工具来变通shapefile中的所有点，以便继续生活?
通常:有人可以指导我如何正确使用此库吗?
In general: Would someone please instruct me on how to properly use this library?
非常感谢您的光临.
推荐答案
由于我不知道RGeo甚至是Ruby，所以在黑暗中是一个狂野的刺，请尝试用等效于米的英尺替换您的坐标:1832244.0944819663048746863094224，640342.57048223700783128534419392 (尽管您可能不需要小数位数...)另一种可能性是交换坐标-也许RGeo做出了一些非常规的假设.
As a wild stab in the dark, because I don't know RGeo or even Ruby, try substituting your coordinates in feet with their metres equivalent: 1832244.0944819663048746863094224, 640342.57048223700783128534419392 (you probably won't need that number of decimal places though...) Another possibility is to swap the coordinates around - maybe RGeo makes some unconventional assumptions.
如果您能够从Ruby调用可执行文件，则只需使用 ogr2ogr 来转换您的shapefile.
If you are able to call executables from Ruby, you could simply use ogr2ogr to convert your shapefiles.
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