このコミュニティは初めてでGIS初心者なので、もし間違った場所に投稿していたらご容赦ください。 <\/P>
北アメリカ全体で種の存在（モナーク蝶）をマッピングしています。どの座標系を使うべきか分からず困っています。Googleで調べたところ、いくつか矛盾した答えが出てきました。Web Mercatorを考えていましたが、分析全体を行って間違っていたら困るので、アドバイスをお願いします！<\/P>
It probably depends on your analysis, but generally, web mercator is a bad idea for analysis, given how much distortion it introduces.
As a fun aside, checkout Mercator: EXTREME. It lets you place the north pole somewhere else, and see what a web mercator projection might look like based on that new pole.
You'd probably be okay going with something like an Albers projection. It's what the USGS uses, if that sways your opinion.
Thank you! That was the other option I was thinking. Now the points themselves on the map, they should also be in Albers? Or should just my map frame and North America polygon?
Any analysis output will probably default to the projection of the input data unless otherwise specified. I'd keep it all in the same projection, myself, but you don't have to.
Perfect. Thanks so much for the help!
Hi @CarlyConticchio1
I recommend North America Albers Equal Area Conic. If any of your analysis involves area or distance measurements, you'll want an equal area projection.
As @jcarlson said, your map frame is probably using the same coordinate system as your data. But you should probably check to make sure it is. If you are using ArcGIS Pro, you can check it here:
When you Geoprocessing tools, they will use the coordinate system of the input data to compute the analysis.
Not to detract to much from some responses, they are good information.
I will always suggest this projection for all GIS Projects until something more universally functional comes along.
WGS_1984_Web_Mercator_Auxiliary_SphereWKID: 3857 Authority: EPSG
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