Hi, I would need to deliver a result shapefile in WGS 84 (GCS: Geographic –lat/lon- coordinate system), the shapefile is originally in WGS84; but in the process of creating this result shapefile I need:
Then, the corresponding solutions I find in ArcGIS, and associate doubts, are:
The doubts are these:
* Change the Data frame coordinate reference system to WGS84, and
* On the result raster, do Data > Export Data and, for the option “Use the same coordinate system as:”, choose “the data frame”,
is this an accurate way of dealing with that? I mean, aren’t there modifications in areas or coordinates of the delivered shape layer?
Thanks for any advice or idea.
(Note: This is a late answer, probably due to discussions being moved around this week.)
It depends somewhat on which version you have. I think you're better off working in an equal area projection like Albers, customized to the area of interest. That allows you to calculate areas, use linear cell sizes, etc. Once you've done all the processing, use the Project and/or Project Raster tools to create data in WGS84.
Although, note this from the help at 10.2:
Python expressions can use the geometry area and length properties with an areal or linear unit to convert the value to a different unit of measure (for example, !shape.length@kilometers!). If the data is stored in a geographic coordinate system and a linear unit is supplied (for example, miles), the length will be calculated using a geodesic algorithm. Using areal units on geographic data will yield questionable results as decimal degrees are not consistent across the globe.
- Areal unit of measure keywords:
- ACRES | ARES | HECTARES | SQUARECENTIMETERS | SQUAREDECIMETERS | SQUAREINCHES | SQUAREFEET | SQUAREKILOMETERS | SQUAREMETERS | SQUAREMILES | SQUAREMILLIMETERS | SQUAREYARDS | SQUAREMAPUNITS | UNKNOWN
I can't remember if Calculate Geometry has been updated for geodesic-based areas in 10.2, but the above can be done through Calculate Field.
On your second question/doubt, using the Export Data option and selecting 'use the data's coordinate system' will return a copy of the original feature class. You're correct on the procedure for your 3rd question too.
re 3rd question: I no longer trust/use "Use the same coordinate system as:”, choose “the data frame" to get to GCS WGS84 from a local Albers-NAD83. I found it did not (re)project the TOC feature class at all. I now only use Model Builder and invoke the Project Tool in a Model Builder work flow.