在D3中加载TopoJSON文件时出现随机行 [英] Random lines when loading a TopoJSON file in D3

问题描述

我正在尝试显示意大利制图的形状文件，例如这个，使用D3.js

I'm trying to display the Italian cartographic shapefiles, for example this one, using D3.js

我可以在 MapShaper 上加载Zip文件，查看地图，对其进行简化并导出到TopoJSON.我可以在MapShaper中加载TopoJSON，但看起来仍然没问题.

I can load the Zip file on MapShaper, look at the map, simplify it and export to TopoJSON. I can load back the TopoJSON in MapShaper and it still looks ok.

但是当我尝试使用D3.js显示它时，我得到了一堆意大利面:

But when I try to display it using D3.js, I get a bunch of spaghetti:

美女，不是吗?

代码直接来自示例.投影中心，旋转和平行线应该是意大利的标准格式，但这并不重要:地图仍然像意大利面条一样，可以选择任何投影.

The code is taken straight from the examples. The projection center, rotation, and parallels are supposed to be the canonical ones for Italy, but it doesn't really matter: the map remains spaghetti-like with any choice of projection.

width = 600
height = 1200

projection = d3.geo.albers()
    .center [0, 41]
    .rotate [347, 0]
    .parallels [35, 45]
    .scale 2000
    .translate [width / 2, height / 2]

path = d3.geo.path()
    .projection projection

svg = d3.select "body"
    .append "svg"
    .attr "width", width
    .attr "height", height

d3.json "Reg2011_ED50.json", (json) ->
    svg.append "path"
        .datum topojson.feature json, json.objects.Reg2011_ED50
        .attr "d", path

我在做什么错了?

推荐答案

我发现了一个旧的邮件列表帖子，其中详细介绍了如何导入这些确切的文件.

I found an old mailing list post detailing how to import those exact files.

基本上，我需要使用以下命令将投影转换为标准投影:

Basically I needed to convert the projection to a standard one with this command:

ogr2ogr -t_srs EPSG:4326 converted.shp original.shp

我不明白为什么需要它:我认为.prj文件解决了投影差异.显然不是.

I don't understand why it's needed: I thought the .prj file took care of projection differences. Apparently not.

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