topic Re: is calculate field using geodesic in ArcGIS Pro Questions

is calculate field using geodesic

StevenSchwartz1 — Mon, 09 Nov 2020 16:58:48 GMT

when using calculate field are the comps using geodesic or planar methods?

Re: is calculate field using geodesic

DanPatterson — Sun, 12 Dec 2021 04:53:15 GMT

you can access geodesic using arcpy in field calculations,

for example

getArea ({type}, {units})
Type: PLANAR measurements reflect the projection of geographic data onto the 2D surface
(in other words, they will not take into account the curvature of the earth).
GEODESIC, GREAT_ELLIPTIC, LOXODROME, and PRESERVE_SHAPE measurement types may be chosen as an alternative, if desired.

but if you are calculating geometry attributes, there are options to do so explicitly in several tools, for instance

Add Geometry Attributes (Data Management)—ArcGIS Pro | Documentation

Re: is calculate field using geodesic

StevenSchwartz1 — Mon, 09 Nov 2020 18:35:30 GMT

It is not my intention to use geodesic computations. I would like to know if/when using the Calculate Field or Calculate Geometry for area computations, are they using planar or geodesic methods? Is it set by the data frame or geodatabase source?

Re: is calculate field using geodesic

DanPatterson — Mon, 09 Nov 2020 19:32:31 GMT

if everything is in a projected coordinate system, then that would be the default.

although I have learned that explicit is better than implicit

Re: is calculate field using geodesic

StevenSchwartz1 — Mon, 09 Nov 2020 19:50:30 GMT

Thank you - can you give me an opinion on the area calculations...which is more accurate? Calculate Field which I divide the shape area by 43560 for acreage, or Calculate Geometry using the area property drop down, acres unit. I am getting a slight difference for all of my computations.